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To: Users
From: Bob Supnik
Subj: Simulator Usage, V2.5
Date: 1-Jan-01
COPYRIGHT NOTICE
The following copyright notice applies to both the SIMH source and binary:
Original code published in 1993-2000, written by Robert M Supnik
Copyright (c) 1993-2000, Robert M Supnik
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
ROBERT M SUPNIK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Except as contained in this notice, the name of Robert M Supnik shall not
be used in advertising or otherwise to promote the sale, use or other dealings
in this Software without prior written authorization from Robert M Supnik.
This memorandum documents the PDP-8, PDP-11, PDP-1, other 18b PDP, Nova,
IBM 1401, HP 2100, and Interdata 4 simulators. These simulators are freeware;
refer to the license terms above for conditions of use. Support is not available.
The best way to fix problems or add features is to read and modify the sources
yourself. Alternately, you can send Internet mail to mps@tiac.net, but
a response is not guaranteed.
The simulators use a common command interface. The memorandum first
describes the common features of the command interface and then provides
information on each of the individual simulators.
1. Compiling And Running A Simulator
The simulators have been tested on VAX VMS, Alpha VMS, Alpha UNIX, Intel
FreeBSD, Intel LINUX, and Windows 95/Windows NT (Visual C++ environment).
Porting to other environments will require changes to the operating system
dependent code in scp_tty.c.
To compile the simulators on VMS, use these commands (note that separate
compilations are required for each of the 18b PDP's):
$ cc pdp8_*.c,scp.c,scp_tty.c ! PDP-8
$ link/exec=pdp8 pdp8_*.obj,scp.obj,scp_tty.obj
$ cc pdp11_*.c,scp.c,scp_tty.c ! PDP-11
$ link/exec=pdp11 pdp11_*.obj,scp.obj,scp_tty.obj
$ cc nova_*.c,scp.c,scp_tty.c ! Nova
$ link/exec=nova nova_*.obj,scp.obj,scp_tty.obj
$ cc pdp1_*.c,scp.c,scp_tty.c ! PDP-1
$ link/exec=pdp1 pdp1_*.obj,scp.obj,scp_tty.obj
$ cc/define=PDP{4,7,9,15} pdp18b_*.c,scp.c,scp_tty.c
$ link/exec=pdp{4,7,9,15} pdp18b_*.obj,scp.obj,scp_tty.obj
$ cc i1401_*.c,scp.c,scp_tty.c ! IBM 1401
$ link/exec=i1401 i1401_*.obj,scp.obj,scp_tty.obj
$ cc hp2100_*.c,scp.c,scp_tty.c ! HP 2100
$ link/exec=hp2100 hp2100_*.obj,scp.obj,scp_tty.obj
$ cc id4_*.c,scp.c,scp_tty.c ! Interdata 4
$ link/exec=id4 id4_*.obj,scp.obj,scp_tty.obj
On version of VMS prior to 6.2, the simulators must then be defined as
foreign commands so that they can be started by name.
To compile the simulators on Alpha UNIX or any UNIX variant which supports
the POSIX compliant TERMIOS interface, use the following commands (note
that separate compilations are required for each of the 18b PDP's):
% cc pdp8_*.c scp*.c -lm -o pdp8
% cc pdp11_*.c scp*.c -lm -o pdp11
% cc nova_*.c scp*.c -lm -o nova
% cc pdp1_*.c scp*.c -o pdp1
% cc -DPDP{4,7,9,15} pdp18b_*.c scp*.c -lm -o pdp{4,7,9,15}
% cc i1401_*.c scp*.c -o i1401
% cc hp2100_*.c scp*.c -o hp2100
% cc id4_*.c scp*.c -o id4
These commands should work with most UNIX variants. If your UNIX only
supports the old BSD terminal interface, add -DBSDTTY to each command.
If your UNIX automatically includes the math library, omit -lm from
the command line.
To start the simulator, simply type its name. The simulator takes
one optional argument, a startup command file. If specified, this
file should contain a series of non-interactive simulator commands,
one per line. These command can be used to set up standard parameters,
for example, disk sizes.
% pdp8 <startup file>(cr) or
% pdp11 <startup file>(cr) or
% nova <startup file>(cr) or
% pdp1 <startup file>(cr) or
% pdp{4,7,9,15} <startup file>(cr) or
% i1401 <startup file>(cr) or
% hp2100 <startup file>(cr) or
% id4 <startup file>(cr)
The simulator types out its name and version, executes the commands
in the startup file, if any, and then prompts for input with
sim>
2. Simulator Conventions
A simulator consists of a series of devices, the first of which is always
the CPU. A device consists of named registers and one or more numbered
units. Registers correspond to device state, units to device address
spaces. Thus, the CPU device might have registers like PC, ION, etc,
and a unit corresponding to main memory; a disk device might have
registers like BUSY, DONE, etc, and units corresponding to individual
disk drives. Except for main memory, device address spaces are simulated
as unstructured binary disk files in the host file system. The SHOW CONFIG
command displays the simulator configuration.
A simulator keeps time in terms of arbitrary units, usually one time unit
per instruction executed. Simulated events (such as completion of I/O)
are scheduled at some number of time units in the future. The simulator
executes synchronously, invoking event processors when simulated events
are scheduled to occur. Even asynchronous events, like keyboard input,
are handled by polling at synchronous intervals. The SHOW QUEUE command
displays the simulator event queue.
3. Commands
Simulator commands consist of a command verb, optional switches, and optional
arguments. Switches take the form:
-<letter>{<letter>...}
Multiple switches may be specified separately or together: -abcd or
-a -b -c -d are treated identically. Verbs, switches, and other
input (except for file names) are case insensitive.
3.1 Loading and Saving Programs
The LOAD command (abbreviation LO) loads a file in binary paper-tape
loader format:
sim> load <filename> {implementation options}(cr)
The number of formats supported is implementation specific. Options
(such as load within range) are also implementation specific.
The DUMP command (abbreviation DU) dumps memory in binary paper-
tape loader format:
sim> dump <filename> {implementation options}(cr)
The number of formats supported is implementation specific. Options
(such as dump within range) are also implementation specific.
3.2 Saving and Restoring State
The SAVE command (abbreviation SA) save the complete state of the
simulator to a file. This includes the contents of main memory and
all registers, and the I/O connections of devices:
sim> save <filename>(cr)
The RESTORE command (abbreviation REST, alternately GET) restores a
previously saved simulator state:
sim> restore <filename>(cr)
Note: SAVE file format compresses zeroes to minimize file size.
3.3 Resetting Devices
The RESET command (abbreviation RE) resets a device or the entire
simulator to a predefined condition:
sim> RESET(cr) -- reset all devices
sim> RESET ALL(cr) -- reset all devices
sim> RESET <device>(cr) -- reset specified device
Typically, RESET stops any in-progress I/O operation, clears any
interrupt request, and returns the device to a quiescent state. It
does not clear main memory or affect I/O connections.
3.4 Connecting and Disconnecting Devices
Except for main memory, simulated unit address spaces are simulated as
unstructured binary disk files in the host file system. Before using a
simulated unit the user must specify the file to be accessed by that
unit. The ATTACH (abbreviation AT) command associates a unit and a file:
sim> ATTACH <device><unit number> <filename>(cr)
If the file does not exist, it is created, and an appropriate message
is printed.
The DETACH (abbreviation DET) command breaks the association between a
unit and a file and closes the file:
sim> DETACH ALL(cr) -- detach all units
sim> DETACH <device><unit number>(cr) -- detach specified unit
The EXIT command performs an automatic DETACH ALL.
3.5 Examining and Changing State
There are four commands to examine and change state:
EXAMINE (abbreviated E) examines state
DEPOSIT (abbreviated D) changes state
IEXAMINE (interactive examine, abbreviated IE) examines state
and allows the user to interactively change it
IDEPOSIT (interactive deposit, abbreviated ID) allows the user
to interactively change state
All four commands take the form
command {modifiers} <state list>
Deposit must also include a deposit value at the end of the command.
There are four kinds of modifiers: switches, device/unit name, search
specifiers, and for EXAMINE, output file. Switches have been described
previously. A device/unit name identifies the device and unit whose
address space is to be examined or modified. If no device is specified,
the CPU (main memory)is selected; if a device but no unit is specified,
unit 0 of the device is selected.
Search specifiers provide criteria for testing addresses or registers
to see if they should be processed. A specifier consists of a logical
operator, a relational operator, or both, optionally separated by spaces.
{<logical op> <value>} <relational op> <value>
where the logical operator is & (and), | (or), or ^ (xor), and the
relational operator is = or == (equal), ! or != (not equal), >=
(greater than or equal), > (greater than), <= (less than or equal), or
< (less than). If a logical operator is specified without a relational
operator, it is ignored. If a relational operator is specified without
a logical operator, no logical operation is performed. All comparisons
are unsigned.
The output file modifier redirects command output to a file instead of
the console. An output file modifier consists of @ followed by a
valid file name.
Modifiers may be specified in any order. If multiple modifiers of the
same time are specified, later modifiers override earlier modifiers.
Note that if the device/unit name comes after the search specifier,
the values will interpreted in the radix of the CPU, rather than of the
device/unit.
The "state list" consists of one or more of the following, separated
by commas:
register the specified register
register1-register2 all the registers starting at register1
up to and including register2
address the specified location
address1-address2 all locations starting at address1 up to
and including address2
STATE all registers in the device
ALL all locations in the unit
Switches can be used to control the format of display information:
-a display as ASCII
-c display as character string
-m display as instruction mnemonics
-o display as octal
-d display as decimal
-h display as hexidecimal
The simulators typically accept symbolic input (see simulator sections).
Examples:
sim> ex 1000-1100 -- examine 1100:1100
sim> de PC 1040 -- set PC to 1040
sim> ie 40-50 -- interactively examine 40:50
sim> ie >1000 40-50 -- interactively examine the subset
of locations 40:50 that are >1000
sim> ex rx0 50060 -- examine 50060, RX unit 0
sim> de all 0 -- set main memory to 0
sim> de &77 >0 0 -- set all addresses whose low order
bits are non-zero to 0
sim> ex -m @memdump.txt 0-7777 -- dump memory to file
Note: to terminate an interactive command, simply type a bad value (eg,
XYZ) when input is requested.
3.6 Running Programs
The RUN command (abbreviated RU) resets all devices, deposits its argument
(if given) in the PC, and starts execution. If no argument is given,
execution starts at the current PC.
The GO command does NOT reset devices, deposits its argument (if given) in
the PC, and starts execution. If no argument is given, execution starts at
the current PC.
The CONT command (abbreviated CO) does NOT reset devices and resumes
execution at the current PC.
The STEP command (abbreviated S) resumes execution at the current PC for
the number of instructions given by its argument. If no argument is
supplied, one instruction is executed.
The BOOT command (abbreviated BO) bootstraps the device and unit given
by its argument. If no unit is supplied, unit 0 is bootstrapped. The
specified unit must be attached to a file.
3.7 Stopping Programs
Programs run until the simulator detects an error or stop condition, or
until the user forces a stop condition.
3.7.1 Simulator Detected Stop Conditions
These simulator-detected conditions stop simulation:
- HALT instruction. If a HALT instruction is decoded,
simulation stops.
- Breakpoint. The IBKPT register provides a single virtual
address breakpoint. If the PC matches the contents of the
IBKPT register, simulation stops. The breakpoint is
automatically disabled for the next instruction execution.
- I/O error. If an I/O error occurs during simulation of an
I/O operation, and the device stop-on-I/O-error flag is set,
simulation usually stops.
- Processor condition. Certain processor conditions can stop
simulation; these are described with the individual simulators.
3.7.2 User Specified Stop Conditions
Typing the interrupt character stops simulation. The interrupt character
is defined by the WRU (where are you) register and is initially set to
005 (^E).
3.8 Setting Device Parameters
The SET command (abbreviated SE) changes the status of a device parameter:
sim> SET <unit> <parameter>
Most parameters are simulator and device specific. Disk drives, for
example, can usually be set write ENABLED or write LOCKED; if a device
supports multiple drive types, the SET command can be used to specify
the drive type.
All devices recognize the following parameters:
OCT sets the data radix = 8
DEC sets the data radix = 10
HEX sets the data radix = 16
3.9 Displaying Parameters and Status
The SHOW CONFIGURATION command shows the simulator configuration and the
status of all simulated devices.
The SHOW MODIFIERS command shows the modifiers available on all simulated
devices.
The SHOW <device> command shows the status of the named simulated device.
The SHOW QUEUE command shows the state of the simulator event queue. Times
are in "simulation units", typically one unit per instruction execution,
relative to the current simulation time.
The SHOW TIME command shows the number of time units elapsed since
the last RUN command.
3.10 Altering the Simulated Configuration
In devices with multiple units, the REMOVE <unit> command removes the
specified unit from the configuration. Once removed, a unit cannot be
manipulated in any way until it is added back to the configuration.
ADD <unit> adds back a unit that had been removed from the configuration.
3.11 Exiting The Simulator
EXIT (synonyms QUIT and BYE) returns control to the operating system.
4. PDP-8 Features
The PDP-8 simulator is configured as follows:
device simulates
name(s)
CPU PDP-8/E CPU with 32KW of memory
- KE8E extended arithmetic element (EAE)
- KM8E memory management and timeshare control
PTR,PTP PC8E paper tape reader/punch
TTI,TTO KL8E console terminal
LPT LE8E line printer
CLK DK8E line frequency clock (also PDP-8/A compatible)
RK RK8E/RK05 cartridge disk controller with four drives
RF RF08/RS08 fixed head disk controller with four platters
RX RX8E/RX01 floppy disk controller with two drives
MT TM8E/TU10 magnetic tape controller with eight drives
The PDP-8 simulator implements one unique stop condition: if an undefined
instruction (unimplemented IOT or OPR) is decoded, and register STOP_INST
is set, the simulator halts.
The PDP-8 loader supports both RIM format and BIN format tapes. BIN is
the default; to load a RIM format tape, use the -r switch with LOAD. The
DUMP command is not implemented.
4.1 CPU
The only CPU options are the presence of the EAE and the size of main
memory; the memory extension and time-share control is always included,
even if memory size is 4K.
SET CPU EAE enable EAE
SET CPU NOEAE disable EAE
SET CPU 4K set memory size = 4K
SET CPU 8K set memory size = 8K
SET CPU 12K set memory size = 12K
SET CPU 16K set memory size = 16K
SET CPU 20K set memory size = 20K
SET CPU 24K set memory size = 24K
SET CPU 28K set memory size = 28K
SET CPU 32K set memory size = 32K
If memory size is being reduced, and the memory being truncated contains
non-zero data, the simulator asks for confirmation. Data in the truncated
portion of memory is lost. Initial memory size is 32K.
CPU registers include the visible state of the processor as well as the
control registers for the interrupt system.
name size comments
PC 15 program counter, including IF as high 3 bits
AC 12 accumulator
MQ 12 multiplier-quotient
L 1 link
SR 12 front panel switches
IF 3 instruction field
DF 3 data field
IB 3 instruction field buffer
SF 7 save field
UF 1 user mode flag
UB 1 user mode buffer
SC 5 EAE shift counter
GTF 1 EAE greater than flag
EMODE 1 EAE mode (0 = A, 1 = B)
ION 1 interrupt enable
ION_DELAY 1 interrupt enable delay for ION
CIF_DELAY 1 interrupt enable delay for CIF
PWR_INT 1 power fail interrupt
UF_INT 1 user mode violation interrupt
INT 15 interrupt pending flags
DONE 15 device done flags
ENABLE 15 device interrupt enable flags
OLDPC 15 PC prior to last JMP, JMS, or interrupt
STOP_INST 1 stop on undefined instruction
BREAK 16 breakpoint address (177777 to disable)
WRU 8 interrupt character
4.2 Programmed I/O Devices
4.2.1 PC8E Paper Tape Reader (PTR)
The paper tape reader (PTR) reads data from a disk file. The POS
register specifies the number of the next data item to be read. Thus,
by changing POS, the user can backspace or advance the reader.
The paper tape reader supports the BOOT command. BOOT PTR copies the
RIM loader into memory and starts it running.
The paper tape reader implements these registers:
name size comments
BUF 8 last data item processed
DONE 1 device done flag
ENABLE 1 interrupt enable flag
INT 1 interrupt pending flag
POS 31 position in the input file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape
end of file 1 report error and stop
0 out of tape
OS I/O error x report error and stop
4.2.2 PC8E Paper Tape Punch (PTP)
The paper tape punch (PTP) writes data to a disk file. The POS register
specifies the number of the next data item to bewritten. Thus, by
changing POS, the user can backspace or advance the punch.
The paper tape punch implements these registers:
name size comments
BUF 8 last data item processed
DONE 1 device done flag
ENABLE 1 interrupt enable flag
INT 1 interrupt pending flag
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape
OS I/O error x report error and stop
4.2.3 KL8E Terminal Input (TTI)
The terminal input (TTI) reads from the controling console port. The
input side has one option, UC; when set, it automatically converts lower
case input to upper case. This is required by OS/8 and is on by default.
The terminal input implements these registers:
name size comments
BUF 8 last data item processed
DONE 1 device done flag
ENABLE 1 interrupt enable flag
INT 1 interrupt pending flag
POS 31 number of characters input
TIME 24 keyboard polling interval
4.2.4 KL8E Terminal Output (TTO)
The terminal output (TTO) writes to the controling console port. It
implements these registers:
name size comments
BUF 8 last data item processed
DONE 1 device done flag
ENABLE 1 interrupt enable flag
INT 1 interrupt pending flag
POS 31 number of characters output
TIME 24 time from I/O initiation to interrupt
4.2.5 LE8E Line Printer (LPT)
The line printer (LPT) writes data to a disk file. The POS register
specifies the number of the next data item to be read or written. Thus,
by changing POS, the user can backspace or advance the printer.
The line printer implements these registers:
name size comments
BUF 8 last data item processed
ERR 1 error status flag
DONE 1 device done flag
ENABLE 1 interrupt enable flag
INT 1 interrupt pending flag
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 set error flag
OS I/O error x report error and stop
4.2.6 DK8E Line-Frequency Clock (CLK)
The real-time clock (CLK) implements these registers:
name size comments
DONE 1 device done flag
ENABLE 1 interrupt enable flag
INT 1 interrupt pending flag
TIME 24 clock interval
4.3 RK8E Cartridge Disk (RK)
RK8E options include the ability to make units write enabled or write locked:
SET RKn LOCKED set unit n write locked
SET RKn ENABLED set unit n write enabled
Units can also be REMOVEd or ADDed to the configuration.
The RK8E implements these registers:
name size comments
STA 12 status
DA 12 disk address
MA 12 current memory address
CMD 12 disk command
BUSY 1 control busy flag
INT 1 interrupt pending flag
STIME 24 seek time, per cylinder
RTIME 24 rotational delay
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 disk not ready
end of file x assume rest of disk is zero
OS I/O error x report error and stop
4.4 RX8E/RX01 Floppy Disk (RX)
RX8E options include the ability to set units write enabled or write locked:
SET RXn LOCKED set unit n write locked
SET RXn ENABLED set unit n write enabled
The RX8E implements these registers:
name size comments
RXCS 12 status
RXDB 12 data buffer
RXES 8 error status
RXTA 8 current track
RXSA 8 current sector
STAPTR 3 controller state
BUFPTR 3 buffer pointer
INT 1 interrupt pending flag
DONE 1 device done flag
ENABLE 1 interrupt enable flag
TR 1 transfer ready flag
ERR 1 error flag
CTIME 24 command completion time
STIME 24 seek time, per track
XTIME 24 transfer ready delay
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 disk not ready
RX01 data files are buffered in memory; therefore, end of file and OS
I/O errors cannot occur.
4.5 RF08/RS08 Fixed Head Disk (RF)
The RF08 implements these registers:
name size comments
STA 12 status
DA 20 current disk address
MA 12 memory address (in memory)
WC 12 word count (in memory)
WLK 32 write lock switches
INT 1 interrupt pending flag
DONE 1 device done flag
TIME 24 rotational delay, per word
BURST 1 burst flag
STOP_IOE 1 stop on I/O error
The RF08 is a three-cycle data break device. If BURST = 0, word transfers
are scheduled individually; if BURST = 1, the entire transfer occurs in
a single data break.
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 disk not ready
RF08 data files are buffered in memory; therefore, end of file and OS
I/O errors cannot occur.
4.6 TM8E Magnetic Tape (MT)
Magnetic tape options include the ability to make units write enabled or
or write locked.
SET MTn LOCKED set unit n write locked
SET MTn ENABLED set unit n write enabled
Units can also be REMOVEd or ADDed to the configuration.
The magnetic tape controller implements these registers:
name size comments
CMD 12 command
FNC 12 function
CA 12 memory address
WC 12 word count
DB 12 data buffer
STA 12 main status
STA2 6 secondary status
DONE 1 device done flag
INT 1 interrupt pending flag
STOP_IOE 1 stop on I/O error
TIME 24 record delay
UST0..7 24 unit status, units 0..n
POS0..7 31 position, units 0..n
Error handling is as follows:
error processed as
not attached tape not ready
end of file (read or space) end of physical tape
(write) ignored
OS I/O error report error and stop
4.7 Symbolic Display and Input
The PDP-8 simulator implements symbolic display and input. Display is
controlled by command line switches:
-a display as ASCII character
-c display as (sixbit) character string
-m display instruction mnemonics
Input parsing is controlled by the first character typed in or by command
line switches:
' or -a ASCII character
" or -c two character sixbit string
alphabetic instruction mnemonic
numeric octal number
Instruction input uses standard PDP-8 assembler syntax. There are four
instruction classes: memory reference, IOT, field change, and operate.
Memory reference instructions have the format
memref {I} {C/Z} address
where I signifies indirect, C a current page reference, and Z a zero page
reference. The address is an octal number in the range 0 - 07777; if C or
Z is specified, the address is a page offset in the range 0 - 177. Normally,
C is not needed; the simulator figures out from the address what mode to use.
However, when referencing memory outside the CPU (eg, disks), there is no
valid PC, and C must be used to specify current page addressing.
IOT instructions consist of single mnemonics, eg, KRB, TLS. IOT instructions
may be or'd together
iot iot iot...
The simulator does not check the legality of the proposed combination. IOT's
for which there is no opcode may be specified as IOT n, where n is an octal
number in the range 0 - 0777.
Field change instructions (CIF, CDF) have the format
fldchg field
where field is an octal number in the range 0 - 7. Field change instructions
may be or'd together.
Operate instructions have the format
opr opr opr...
The simulator does not check the legality of the proposed combination. EAE
mode A and B mnemonics may be specified regardless of the EAE mode. The
operands for MUY and DVI must be deposited explicitly.
5. PDP-11 Features
The PDP-11 simulator is configured as follows:
device simulates
name(s)
CPU J-11 CPU with 256KB of memory
- FP11 floating point unit (FPA)
- CIS11 commercial instruction set (CIS, off by default)
PTR,PTP PC11 paper tape reader/punch
TTI,TTO DL11 console terminal
LPT LP11 line printer
CLK line frequency clock
RK RK11/RK05 cartridge disk controller with eight drives
RL RLV12/RL01(2) cartridge disk controller with four drives
RP RM02/03/05/80, RP04/05/06/07 Massbus style controller
with eight drives
RX RX11/RX01 floppy disk controller with two drives
TM TM11/TU10 magnetic tape controller with eight drives
The PDP-11 simulator implements several unique stop conditions:
- abort during exception vector fetch, and register STOP_VEC is set
- abort during exception stack push, and register STOP_SPA is set
- trap condition 'n' occurs, and register STOP_TRAP<n> is set
- wait state entered, and no I/O operations outstanding
(ie, no interrupt can ever occur)
The PDP-11 loader supports standard binary format tapes. The DUMP command
is not implemented.
5.1 CPU
The only CPU options are disabling of 22b addressing, the CIS instruction
set, and the size of main memory.
SET CPU 18B disable 22b addressing
SET CPU 22B enable 22b addressing (default)
SET CPU NOCIS disable CIS instructions (default)
SET CPU CIS enable CIS instructions
SET CPU 16K set memory size = 16KB
SET CPU 32K set memory size = 32KB
SET CPU 48K set memory size = 48KB
SET CPU 64K set memory size = 64KB
SET CPU 96K set memory size = 96KB
SET CPU 128K set memory size = 128KB
SET CPU 192K set memory size = 192KB
SET CPU 256K set memory size = 256KB
SET CPU 384K set memory size = 384KB
SET CPU 512K set memory size = 512KB
SET CPU 768K set memory size = 768KB
SET CPU 1024K (or 1M) set memory size = 1024KB
SET CPU 2048K (or 2M) set memory size = 2048KB
SET CPU 3072K (or 3M) set memory size = 3072KB
SET CPU 4096K (or 4M) set memory size = 4096KB
If memory size is being reduced, and the memory being truncated contains
non-zero data, the simulator asks for confirmation. Data in the truncated
portion of memory is lost. Initial memory size is 256KB.
These switches are recognized when examining or depositing in CPU memory:
-v interpret address as virtual
-d if mem mgt enabled, force data space
-k if mem mgt enabled, force kernel mode
-s if mem mgt enabled, force supervisor mode
-u if mem mgt enabled, force user mode
-p if mem mgt enabled, force previous mode
CPU registers include the visible state of the processor as well as the
control registers for the interrupt system.
name size comments
PC 16 program counter
R0..R5 16 R0..R5, first register set
R10..R15 16 R0..R5, second register set
KSP 16 kernel stack pointer
SSP 16 supervisor stack pointer
USP 16 user stack pointer
PSW 16 processor status word
CM 2 current mode, PSW<15:14>
PM 2 previous mode, PSW<13:12>
RS 2 register set, PSW<11>
IPL 3 interrupt priority level, PSW<7:5>
T 1 trace bit, PSW<4>
N 1 negative flag, PSW<3>
Z 1 zero flag, PSW<2>
V 1 overflow flag, PSW<1>
C 1 carry flag, PSW<0>
SR 16 front panel switches
DR 16 front panel display
MEMERR 16 memory error register
CCR 16 cache control register
MAINT 16 maintenance register
HITMISS 16 hit/miss register
CPUERR 16 CPU error register
PIRQ 16 programmed interrupt requests
FAC0H..FAC5H 32 FAC0..FAC5, high 32 bits
FAC0L..FAC5L 32 FAC0..FAC5, low 32 bits
FPS 16 floating point status
FEA 16 floating exception address
FEC 4 floating exception code
MMR0..3 16 memory management registers 0..3
{K/S/U}{I/D}{PAR/PDR}{0..7}
16 memory management registers
INT 32 interrupt pending flags
TRAP 18 trap pending flags
WAIT 0 wait state flag
WAIT_ENABLE 0 wait state enable flag
STOP_TRAPS 18 stop on trap flags
STOP_VECA 1 stop on read abort in trap or interrupt
STOP_SPA 1 stop on stack push abort in trap or interrupt
OLDPC 16 PC prior to last JMP, JMS, or interrupt
BREAK 16 breakpoint address (1 to disable)
WRU 8 interrupt character
5.2 Programmed I/O Devices
5.2.1 PC11 Paper Tape Reader (PTR)
The paper tape reader (PTR) reads data from a disk file. The POS
register specifies the number of the next data item to be read. Thus,
by changing POS, the user can backspace or advance the reader.
The paper tape reader implements these registers:
name size comments
BUF 8 last data item processed
CSR 16 control/status register
INT 1 interrupt pending flag
ERR 1 error flag (CSR<15>)
BUSY 1 busy flag (CSR<11>)
DONE 1 device done flag (CSR<7>)
IE 1 interrupt enable flag (CSR<6>)
POS 31 position in the input file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape
end of file 1 report error and stop
0 out of tape
OS I/O error x report error and stop
5.2.2 PC11 Paper Tape Punch (PTP)
The paper tape punch (PTP) writes data to a disk file. The POS
register specifies the number of the next data item to be written.
Thus, by by changing POS, the user can backspace or advance the punch.
The paper tape punch implements these registers:
name size comments
BUF 8 last data item processed
CSR 16 control/status register
INT 1 interrupt pending flag
ERR 1 error flag (CSR<15>)
DONE 1 device done flag (CSR<7>)
IE 1 interrupt enable flag (CSR<6>)
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape
OS I/O error x report error and stop
5.2.3 KL11 Terminal Input (TTI)
The terminal input (TTI) reads from the controling console port. It
implements these registers:
name size comments
BUF 8 last data item processed
CSR 16 control/status register
INT 1 interrupt pending flag
ERR 1 error flag (CSR<15>)
DONE 1 device done flag (CSR<7>)
IE 1 interrupt enable flag (CSR<6>)
POS 31 number of characters input
TIME 24 keyboard polling interval
5.2.4 KL11 Terminal Output (TTO)
The terminal output (TTO) writes to the controling console port. It
implements these registers:
name size comments
BUF 8 last data item processed
CSR 16 control/status register
INT 1 interrupt pending flag
ERR 1 error flag (CSR<15>)
DONE 1 device done flag (CSR<7>)
IE 1 interrupt enable flag (CSR<6>)
POS 31 number of characters input
TIME 24 time from I/O initiation to interrupt
5.2.5 LP11 Line Printer (LPT)
The line printer (LPT) writes data to a disk file. The POS register
specifies the number of the next data item to be written. Thus,
by changing POS, the user can backspace or advance the printer.
The line printer implements these registers:
name size comments
BUF 8 last data item processed
CSR 16 control/status register
INT 1 interrupt pending flag
ERR 1 error flag (CSR<15>)
DONE 1 device done flag (CSR<7>)
IE 1 interrupt enable flag (CSR<6>)
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of paper
OS I/O error x report error and stop
5.2.6 Line-Time Clock (CLK)
The clock (CLK) implements these registers:
name size comments
CSR 16 control/status register
INT 1 interrupt pending flag
DONE 1 device done flag (CSR<7>)
IE 1 interrupt enable flag (CSR<6>)
TIME 24 clock frequency
5.3 RK11/RK05 Cartridge Disk (RK)
RK11 options include the ability to make units write enabled or write locked:
SET RKn LOCKED set unit n write locked
SET RKn ENABLED set unit n write enabled
Units can also be REMOVEd or ADDed to the configuration.
The RK11 implements these registers:
name size comments
RKCS 16 control/status
RKDA 16 disk address
RKBA 16 memory address
RKWC 16 word count
RKDS 16 drive status
RKER 16 error status
INTQ 9 interrupt queue
DRVN 3 number of last selected drive
INT 1 interrupt pending flag
ERR 1 error flag (CSR<15>)
DONE 1 device done flag (CSR<7>)
IE 1 interrupt enable flag (CSR<6>)
INT 1 interrupt pending flag
STIME 24 seek time, per cylinder
RTIME 24 rotational delay
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 disk not ready
end of file x assume rest of disk is zero
OS I/O error x report error and stop
5.4 RX11/RX01 Floppy Disk (RX)
RX11 options include the ability to make units write enabled or write locked:
SET RXn LOCKED set unit n write locked
SET RXn ENABLED set unit n write enabled
The RX11 implements these registers:
name size comments
RXCS 12 status
RXDB 8 data buffer
RXES 8 error status
RXERR 8 error code
RXTA 8 current track
RXSA 8 current sector
STAPTR 3 controller state
BUFPTR 3 buffer pointer
INT 1 interrupt pending flag
ERR 1 error flag (CSR<15>)
TR 1 transfer ready flag (CSR<7>)
IE 1 interrupt enable flag (CSR<6>)
DONE 1 device done flag (CSR<5>)
CTIME 24 command completion time
STIME 24 seek time, per track
XTIME 24 transfer ready delay
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 disk not ready
RX01 data files are buffered in memory; therefore, end of file and OS
I/O errors cannot occur.
5.5 RL11(V12)/RL01,RL02 Cartridge Disk (RL)
RL11 options include the ability to set units write enabled or write locked,
to set the drive size to RL01, RL02, or autosize, and to write a DEC standard
044 compliant bad block table on the last track:
SET RLn LOCKED set unit n write locked
SET RLn ENABLED set unit n write enabled
SET RLn RL01 set size to RL01
SET RLn RL02 set size to RL02
SET RLn AUTOSIZE set size based on file size at attach
SET RLn BADBLOCK write bad block table on last track
The size options can be used only when a unit is not attached to a file. The
bad block option can be used only when a unit is attached to a file. Units
can also be REMOVEd or ADDed to the configuration.
The RL11 implements these registers:
name size comments
RLCS 16 control/status
RLDA 16 disk address
RLBA 16 memory address
RLBAE 6 memory address extension (RLV12)
RLMP..RLMP2 16 multipurpose register queue
INT 1 interrupt pending flag
ERR 1 error flag (CSR<15>)
DONE 1 device done flag (CSR<7>)
IE 1 interrupt enable flag (CSR<6>)
STIME 24 seek time, per cylinder
RTIME 24 rotational delay
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 disk not ready
end of file x assume rest of disk is zero
OS I/O error x report error and stop
5.6 RM02/03/05/80, RP04/05/06/07 Disk Pack Drives (RP)
The RP controller implements a "Massbus style" 22b direct interface for
large disk drives. It is more abstract than other device simulators, with
just enough detail to run operating system drivers. In addition, the RP
controller conflates the details of the RM series controllers with the RP
series controllers, although there were detailed differences.
RP options include the ability to set units write enabled or write locked,
to set the drive size to one of seven disk types, or autosize, and to write
a DEC standard 044 compliant bad block table on the last track:
SET RPn LOCKED set unit n write locked
SET RPn ENABLED set unit n write enabled
SET RPn RM03 set size to RM03
SET RPn RM05 set size to RM05
SET RPn RM80 set size to RM80
SET RPn RP04 set size to RP04
SET RPn RP06 set size to RP06
SET RPn RP07 set size to RP07
SET RPn AUTOSIZE set size based on file size at attach
SET RLn BADBLOCK write bad block table on last track
The size options can be used only when a unit is not attached to a file. The
bad block option can be used only when a unit is attached to a file. Units
can also be REMOVEd or ADDed to the configuration.
The RP controller implements these registers:
name size comments
RPCS1 16 control/status 1
RPCS2 16 control/status 2
RPCS3 16 control/status 3
RPWC 16 word count
RPBA 16 bus address
RPBAE 6 bus address extension
RPDA 16 desired surface, sector
RPDC 8 desired cylinder
RPOF 16 offset
RPDS0..7 16 drive status, drives 0-7
RPDE0..7 16 drive error, drives 0-7
RPER2 16 error status 2
RPER3 16 error status 3
RPDB 16 data buffer
RPMR 16 maintenance register
INT 1 interrupt pending flag
SC 1 special condition (CSR1<15>)
DONE 1 device done flag (CSR1<7>)
IE 1 interrupt enable flag (CSR1<6>)
STIME 24 seek time, per cylinder
RTIME 24 rotational delay
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 disk not ready
end of file x assume rest of disk is zero
OS I/O error x report error and stop
5.7 TM11 Magnetic Tape (TM)
Magnetic tape options include the ability to make units write enabled or
or write locked.
SET TMn LOCKED set unit n write locked
SET TMn ENABLED set unit n write enabled
Units can also be REMOVEd or ADDed to the configuration.
The magnetic tape bootstrap supports both original and DEC standard boot
formats. Originally, a tape bootstrap read and executed the first record
on tape. To allow for ANSI labels, the DEC standard bootstrap skipped the
first record and read and executed the second. The DEC standard is the
default; to bootstrap an original format tape, use the -o switch with the
BOOT command.
The magnetic tape controller implements these registers:
name size comments
MTS 16 status
MTC 16 command
MTCMA 16 memory address
MTBRC 16 byte/record count
INT 1 interrupt pending flag
ERR 1 error flag
DONE 1 device done flag
IE 1 interrupt enable flag
STOP_IOE 1 stop on I/O error
TIME 24 delay
UST0..7 16 unit status, units 0..n
POS0..7 31 position, units 0..n
Error handling is as follows:
error processed as
not attached tape not ready
end of file (read or space) end of physical tape
(write) ignored
OS I/O error report error and stop
5.8 Symbolic Display and Input
The PDP-11 simulator implements symbolic display and input. Display is
controlled by command line switches:
-a display as ASCII character
-c display as two character ASCII string
-m display instruction mnemonics
Input parsing is controlled by the first character typed in or by command
line switches:
' or -a ASCII character
" or -c two character ASCII string
alphabetic instruction mnemonic
numeric octal number
Instruction input uses standard PDP-11 assembler syntax. There are sixteen
instruction classes:
class operands examples comments
no operands none HALT, RESET
3b literal literal, 0 - 7 SPL
6b literal literal, 0 - 077 MARK
8b literal literal, 0 - 0377 EMT, TRAP
register register RTS
sop specifier SWAB, CLR, ASL
reg-sop register, specifier JSR, XOR, MUL
fop flt specifier ABSf, NEGf
ac-fop flt reg, flt specifier LDf, MULf
ac-sop flt reg, specifier LDEXP, STEXP
ac-moded sop flt reg, specifier LDCif, STCfi
dop specifier, specifier MOV, ADD, BIC
cond branch address BR, BCC, BNE
sob register, address SOB
cc clear cc clear instructions CLC, CLV, CLZ, CLN combinable
cc set cc set instructions SEC, SEV, SEZ, SEN combinable
For floating point opcodes, F and D variants, and I and L variants, may be
specified regardless of the state of FPS.
The syntax for specifiers is as follows:
syntax specifier displacement comments
Rn 0n -
Fn 0n - only in flt reg classes
(Rn) 1n -
@(Rn) 7n 0 equivalent to @0(Rn)
(Rn)+ 2n -
@(Rn)+ 3n -
-(Rn) 4n -
@-(Rn) 5n -
{+/-}d(Rn) 6n {+/-}d
@{+/-}d(Rn) 7n {+/-}d
#n 27 n
@#n 37 n
.+/-n 67 +/-n - 4
@.+/-n 77 +/-n - 4
{+/-}n 67 {+/-}n - PC - 4 if on disk, 37 and n
@{+/-}n 77 {+/-}n - PC - 4 if on disk, invalid
6. Nova Features
The Nova simulator is configured as follows:
device simulates
name(s)
CPU Nova CPU with 32KW of memory
- hardware multiply/divide
PTR,PTP paper tape reader/punch
TTI,TTO console terminal
LPT line printer
CLK real-time clock
DK head-per-track disk controller
DP moving head disk controller with four drives
MT magnetic tape controller with eight drives
The Nova simulator implements these unique stop conditions:
- reference to undefined I/O device, and STOP_DEV is set
- more than INDMAX indirect addresses are detected during
an interrupt
- more than INDMAX indirect addresses are detected during
memory reference address decoding
The Nova loader supports standard binary format tapes. The DUMP command
is not implemented.
6.1 CPU
The only CPU options are the presence of the optional instructions
and the size of main memory.
SET CPU NOVA4 enable Nova4 instructions
SET CPU NOVA3 enable Nova3 instructions
SET CPU MDV enable multiply/divide
SET CPU NONE disable all optional instructions
SET CPU 4K set memory size = 4K
SET CPU 8K set memory size = 8K
SET CPU 12K set memory size = 12K
SET CPU 16K set memory size = 16K
SET CPU 20K set memory size = 20K
SET CPU 24K set memory size = 24K
SET CPU 28K set memory size = 28K
SET CPU 32K set memory size = 32K
(Nova 4 = optional multiply/divide, stack, byte, trap instructions)
(Nova 3 = optional multiply/divide, stack instructions)
(MDV = multiply/divide instructions)
If memory size is being reduced, and the memory being truncated contains
non-zero data, the simulator asks for confirmation. Data in the truncated
portion of memory is lost. Initial memory size is 32K.
CPU registers include the visible state of the processor as well as the
control registers for the interrupt system.
name size comments
PC 15 program counter
AC0..AC3 16 accumulators 0..3
C 1 carry
SR 16 front panel switches
PI 16 priority interrupt mask
ION 1 interrupt enable
ION_DELAY 1 interrupt enable delay for ION
PWR 1 power fail interrupt
INT 15 interrupt pending flags
BUSY 15 device busy flags
DONE 15 device done flags
DISABLE 15 device interrupt disable flags
STOP_DEV 1 stop on undefined IOT
INDMAX 15 maximum number of nested indirects
OLDPC 15 PC prior to last JMP, JMS, or interrupt
BREAK 16 breakpoint address (177777 to disable)
WRU 8 interrupt character
6.2 Programmed I/O Devices
6.2.1 Paper Tape Reader (PTR)
The paper tape reader (PTR) reads data from a disk file. The POS
register specifies the number of the next data item to be read. Thus,
by changing POS, the user can backspace or advance the reader.
The paper tape reader implements these registers:
name size comments
BUF 8 last data item processed
BUSY 1 device busy flag
DONE 1 device done flag
DISABLE 1 interrupt disable flag
INT 1 interrupt pending flag
POS 31 position in the input file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
errpr STOP_IOE processed as
not attached 1 report error and stop
0 out of tape or paper
end of file 1 report error and stop
0 out of tape or paper
OS I/O error x report error and stop
6.2.2 Paper Tape Punch (PTP)
The paper tape punch (PTP) writes data to a disk file. The POS
register specifies the number of the next data item to be written.
Thus, by changing POS, the user can backspace or advance the punch.
The paper tape punch implements these registers:
name size comments
BUF 8 last data item processed
BUSY 1 device busy flag
DONE 1 device done flag
DISABLE 1 interrupt disable flag
INT 1 interrupt pending flag
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape or paper
OS I/O error x report error and stop
6.2.3 Terminal Input (TTI)
The terminal input reads from the controling console port. Terminal
options include the ability to set limited Dasher compatibility mode or
normal mode:
SET TTI ANSI normal mode
SET TTI DASHER Dasher mode
SET TTO ANSI normal mode
SET TTO DASHER Dasher mode
Setting either TTI or TTO changes both devices. In Dasher mode, carriage
return is changed to newline on input, and ^X is changed to backspace.
The terminal input implements these registers:
name size comments
BUF 8 last data item processed
BUSY 1 device busy flag
DONE 1 device done flag
DISABLE 1 interrupt disable flag
INT 1 interrupt pending flag
POS 31 number of characters input
TIME 24 keyboard polling interval
6.2.4 Terminal Output (TTO)
The terminal output writes to the controling console port. Terminal
options include the ability to set limited Dasher compatibility mode or
normal mode:
SET TTI ANSI normal mode
SET TTI DASHER Dasher mode
SET TTO ANSI normal mode
SET TTO DASHER Dasher mode
Setting either TTI or TTO changes both devices. In Dasher mode, carriage
return is changed to newline on input, and ^X is changed to backspace.
The terminal output implements these registers:
name size comments
BUF 8 last data item processed
BUSY 1 device busy flag
DONE 1 device done flag
DISABLE 1 interrupt disable flag
INT 1 interrupt pending flag
POS 31 number of characters output
TIME 24 time from I/O initiation to interrupt
6.2.5 Programmed I/O Devices (LPT)
The line printer (LPT) writes data to a disk file. The POS register
specifies the number of the next data item to be written. Thus,
by changing POS, the user can backspace or advance the printer.
The line printer implements these registers:
name size comments
BUF 8 last data item processed
BUSY 1 device busy flag
DONE 1 device done flag
DISABLE 1 interrupt disable flag
INT 1 interrupt pending flag
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of paper
OS I/O error x report error and stop
6.2.6 Real-Time Clock (CLK)
The real-time clock (CLK) implements these registers:
name size comments
SELECT 2 selected clock interval
BUSY 1 device busy flag
DONE 1 device done flag
DISABLE 1 interrupt disable flag
INT 1 interrupt pending flag
TIME0 24 clock frequency, select = 0
TIME1 24 clock frequency, select = 1
TIME2 24 clock frequency, select = 2
TIME3 24 clock frequency, select = 3
6.3 Fixed Head Disk (DK)
The fixed head disk controller implements these registers:
name size comments
STAT 16 status
DA 16 disk address
MA 16 memory address
BUSY 1 device busy flag
DONE 1 device done flag
DISABLE 1 device disable flag
INT 1 interrupt pending flag
WLK 8 write lock switches
TIME 24 rotational delay, per sector
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 disk not ready
Fixed head disk data files are buffered in memory; therefore, end of file
and OS I/O errors cannot occur.
6.4 Moving Head Disk (DP)
Moving head disk options include the ability to make units write enabled or
write locked, and to select the type of drive:
SET DPn LOCKED set unit n write locked
SET DPn ENABLED set unit n write enabled
SET DPn FLOPPY set unit n to floppy disk
SET DPn D31 set unit n to Diablo 31
SET DPn D44 set unit n to Diablo 44
SET DPn C111 set unit n to Century 111
SET DPn C114 set unit n to Century 114
SET DPn 6225 set unit n to 6225
SET DPn 6099 set unit n to 6099
SET DPn 6227 set unit n to 6227
SET DPn 6070 set unit n to 6070
SET DPn 6103 set unit n to 6103
SET DPn 4231 set unit n to 4231
Units can also be REMOVEd or ADDed to the configuration.
All drives have 256 16b words per sector. The other disk parameters are:
drive cylinders surfaces sectors size (MW) DG models
floppy 77 1 8 .158 6038
D31 203 2 12 1.247 4047, 4237, 4238
D44 408 4 12 5.014 4234, 6045
C111 203 10 6 3.118 4048
C114 203 20 12 12.472 4057, 2314
6225 20 2 245 2.508
6099 32 4 192 6.291
6227 20 6 245 7.526
6070 24 4 408 10.027
6103 32 8 192 12.583
4231 23 19 411 45.979
The moving head disk controller implements these registers:
name size comments
FCCY 16 flags, command, cylinder
USSC 16 unit, surface, sector, count
STAT 16 status
MA 16 memory address
BUSY 1 device busy flag
DONE 1 device done flag
DISABLE 1 interrupt disable flag
INT 1 interrupt pending flag
STIME 24 seek time, per cylinder
RTIME 24 rotational delay
Error handling is as follows:
error processed as
not attached disk not ready
end of file assume rest of disk is zero
OS I/O error report error and stop
6.5 Magnetic Tape (MT)
Magnetic tape options include the ability to make units write enabled or
or write locked.
SET MTn LOCKED set unit n write locked
SET MTn ENABLED set unit n write enabled
Units can also be REMOVEd or ADDed to the configuration.
The magnetic tape controller implements these registers:
name size comments
CU 16 command, unit
MA 16 memory address
WC 16 word count
STA1 16 status word 1
STA2 16 status word 2
EP 1 extended polling mode (not supported)
BUSY 1 device busy flag
DONE 1 device done flag
DISABLE 1 interrupt disable flag
INT 1 interrupt pending flag
STOP_IOE 1 stop on I/O error
CTIME 24 controller delay
RTIME 24 record delay
UST0..7 32 unit status, units 0..n
POS0..7 31 position, units 0..n
Error handling is as follows:
error processed as
not attached tape not ready
end of file (read or space) end of physical tape
(write) ignored
OS I/O error report error and stop
6.6 Symbolic Display and Input
The Nova simulator implements symbolic display and input. Display is
controlled by command line switches:
-a display as ASCII character
-c display as two character ASCII string
-m display instruction mnemonics
Input parsing is controlled by the first character typed in or by command
line switches:
' or -a ASCII character
" or -c two character ASCII string
alphabetic instruction mnemonic
numeric octal number
Instruction input uses standard Nova assembler syntax. There are three
instruction classes: memory reference, IOT, and operate.
Memory reference instructions have the format
memref {ac,}{@}address{,index}
LDA and STA require an initial register; ISZ, DSZ, JSR, and JMP do not.
The syntax for addresses and indices is as follows:
syntax mode displacement comments
0 <= n < 0400 0 n
{+/-}n >= 0400 1 {+/-}n - PC must be in range [-200, 177]
invalid on disk
.+/-n 1 {+/-}n must be in range [-200, 177]
{+/-}n,2 2 {+/-}n must be in range [-200, 177]
{+/-}n,3 3 {+/-}n must be in range [-200, 177]
IOT instructions have one of four formats
syntax example
iot HALT
iot reg INTA
iot device SKPDN
iot reg,device DOAS
Devices may be specified as mnemonics or as numbers in the range 0 - 077.
Operate instructions have the format
opcode{#} reg,reg{,skip}
In all Nova instructions, blanks may be substituted for commas as field
delimiters.
7. PDP-1 Features
The PDP-1 is configured as follows:
device simulates
name(s)
CPU PDP-1 CPU with up to 64KW of memory
PTR,PTP integral paper tape reader/punch
TTI,TTO Flexowriter typewriter input/output
LPT Type 62 line printer
The PDP-1 simulator implements the following unique stop conditions:
- an unimplemented instruction is decoded, and register
STOP_INST is set
- more than INDMAX indirect addresses are detected during
memory reference address decoding
- more than XCTMAX nested executes are detected during
instruction execution
- wait state entered, and no I/O operations outstanding
(ie, no interrupt can ever occur)
The PDP-1 loader supports RIM format tapes. The DUMP command is not
implemented.
7.1 CPU
The only CPU options are the presence of hardware multiply/divide and the
size of main memory.
SET CPU MDV enable multiply/divide
SET CPU NOMDV disable multiply/divide
SET CPU 4K set memory size = 4K
SET CPU 8K set memory size = 8K
SET CPU 12K set memory size = 12K
SET CPU 16K set memory size = 16K
SET CPU 20K set memory size = 20K
SET CPU 24K set memory size = 24K
SET CPU 28K set memory size = 28K
SET CPU 32K set memory size = 32K
SET CPU 48K set memory size = 48K
SET CPU 64K set memory size = 64K
If memory size is being reduced, and the memory being truncated contains
non-zero data, the simulator asks for confirmation. Data in the truncated
portion of memory is lost. Initial memory size is 64K.
CPU registers include the visible state of the processor as well as the
control registers for the interrupt system.
name size comments
PC 16 program counter
AC 18 accumulator
IO 18 IO register
OV 1 overflow flag
PF 6 program flags<1:6>
SS 6 sense switches<1:6>
TW 18 test word (front panel switches)
EXTM 1 extend mode
IOSTA 18 IO status register
SBON 1 sequence break enable
SBRQ 1 sequence break request
SBIP 1 sequence break in progress
IOH 1 I/O halt in progress
IOC 1 I/O continue
OLDPC 16 PC prior to last transfer
STOP_INST 1 stop on undefined instruction
SBS_INIT 1 initial state of sequence break enable
EXTM_INIT 1 initial state of extend mode
BREAK 17 breakpoint address (377777 to disable)
WRU 8 interrupt character
7.2 Programmed I/O Devices
7.2.1 Paper Tape Reader (PTR)
The paper tape reader (PTR) reads data from or a disk file. The POS
register specifies the number of the next data item to be read. Thus,
by changing POS, the user can backspace or advance the reader.
The paper tape reader implements these registers:
name size comments
BUF 8 last data item processed
DONE 1 device done flag
RPLS 1 return restart pulse flag
POS 31 position in the input file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape
end of file 1 report error and stop
0 out of tape
OS I/O error x report error and stop
7.2.2 Paper Tape Punch (PTP)
The paper tape punch (PTP) writes data to a disk file. The POS
register specifies the number of the next data item to be written.
Thus, by changing POS, the user can backspace or advance the punch.
The paper tape punch implements these registers:
name size comments
BUF 8 last data item processed
DONE 1 device done flag
RPLS 1 return restart pulse flag
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape
OS I/O error x report error and stop
7.2.3 Terminal Input (TTI)
The terminal input (TTO) reads from the controling console port.
It implements these registers:
name size comments
BUF 8 last data item processed
DONE 1 device done flag
POS 31 number of characters input
TIME 24 keyboard polling interval
7.2.4 Terminal Output (TTO)
The terminal output (TTO) writes to the controling console port.
It implements these registers:
name size comments
BUF 8 last data item processed
DONE 1 device done flag
RPLS 1 return restart pulse flag
POS 31 number of characters output
TIME 24 time from I/O initiation to interrupt
7.2.5 Type 62 Line Printer (LPT)
The paper line printer (LPT) writes data to a disk file. The POS
register specifies the number of the next data item to be written.
Thus, by changing POS, the user can backspace or advance the printer.
The line printer implements these registers:
name size comments
BUF 8 last data item processed
PNT 1 printing done flag
SPC 1 spacing done flag
RPLS 1 return restart pulse flag
BPTR 6 print buffer pointer
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape or paper
OS I/O error x report error and stop
7.3 Symbolic Display and Input
The PDP-1 simulator implements symbolic display and input. Display is
controlled by command line switches:
-a display as ASCII character
-c display as FIODEC character string
-m display instruction mnemonics
Input parsing is controlled by the first character typed in or by command
line switches:
' or -a ASCII character
" or -c three character FIODEC string
alphabetic instruction mnemonic
numeric octal number
Instruction input uses modified PDP-1 assembler syntax. There are six
instruction classes: memory reference, shift, skip, operate, IOT, and
LAW.
Memory reference instructions have the format
memref {I} address
where I signifies indirect reference. The address is an octal number in
the range 0 - 0177777.
Shift instructions have the format
shift shift_count
The shift count is an octal number in the range 0-9.
Skip instructions consist of single mnemonics, eg, SZA, SZS4. Skip
instructions may be or'd together
skip skip skip...
The sense of a skip can be inverted by including the mnemonic I.
Operate instructions consist of single mnemonics, eg, CLA, CLI. Operate
instructions may be or'd together
opr opr opr...
IOT instructions consist of single mnemonics, eg, TYI, TYO. IOT
instructions may include an octal numeric modifier or the modifier I:
iot modifier
The simulator does not check the legality of skip, operate, or IOT
combinations.
Finally, the LAW instruction has the format
LAW {I} immediate
where immediate is in the range 0 to 07777.
7.4 Character Sets
The PDP-1's console was a Frieden Flexowriter; its character encoding
was known as FIODEC. The PDP-1's line printer used a modified Hollerith
character set. The following table provides equivalences between ASCII
characters and the PDP-1's I/O devices. In the console table, UC stands
for upper case.
PDP-1 PDP-1
ASCII console line printer
000 - 007 none none
bs 075 none
tab 036 none
012 - 014 none none
cr 077 none
016 - 037 none none
space 000 000
! {OR} UC+005 none
" UC+001 none
# {IMPLIES} UC+004 none
$ none none
% none none
& {AND} UC+006 none
' UC+002 none
( 057 057
) 055 055
* {TIMES} UC+073 072
+ UC+054 074
, 033 033
- 054 054
. 073 073
/ 021 021
0 020 020
1 001 001
2 002 002
3 003 003
4 004 004
5 005 005
6 006 006
7 007 007
8 010 010
9 011 011
: none none
; none none
< UC+007 034
= UC+033 053
> UC+010 034
? UC+021 037
@ {MID DOT} 040 {MID DOT} 040
A UC+061 061
B UC+062 062
C UC+063 063
D UC+064 064
E UC+065 065
F UC+066 066
G UC+067 067
H UC+070 070
I UC+071 071
J UC+041 041
K UC+042 042
L UC+043 043
M UC+044 044
N UC+045 045
O UC+046 046
P UC+047 047
Q UC+050 050
R UC+051 051
S UC+022 022
T UC+023 023
U UC+024 024
V UC+025 025
W UC+026 026
X UC+027 027
Y UC+030 030
Z UC+031 031
[ UC+057 none
\ {OVERLINE} 056 {OVERLINE} 056
] UC+055 none
^ {UP ARROW} UC+011 {UP ARROW} 035
_ UC+040 UC+040
` {RT ARROW} UC+020 036
a 061 none
b 062 none
c 063 none
d 064 none
e 065 none
f 066 none
g 067 none
h 070 none
i 071 none
j 041 none
k 042 none
l 043 none
m 044 none
n 045 none
o 046 none
p 047 none
q 050 none
r 051 none
s 022 none
t 023 none
u 024 none
v 025 none
w 026 none
x 027 none
y 030 none
z 031 none
{ none none
| UC+056 076
} none none
~ UC+003 013
del 075 none
8. 18b PDP Features
The other four 18b PDP's (PDP-4, PDP-7, PDP-9, PDP-15) are very similar
and are configured as follows:
system device simulates
name(s)
PDP-4 CPU PDP-4 CPU with 8KW of memory
PTR,PTP integral paper tape/Type 75 punch
TTI,TTO KSR28 console terminal (Baudot code)
LPT Type 62 line printer (Hollerith code)
CLK integral real-time clock
PDP-7 CPU PDP-7 CPU with 32KW of memory
- Type 177 extended arithmetic element (EAE)
- Type 148 memory extension
PTR,PTP Type 444 paper tape reader/Type 75 punch
TTI,TTO KSR 33 console terminal
LPT Type 647 line printer
CLK integral real-time clock
DRM Type 24 serial drum
PDP-9 CPU PDP-9 CPU with 32KW of memory
- KE09A extended arithmetic element (EAE)
- KG09B memory extension
- KP09A power detection
- KX09A memory protection
PTR,PTP PC09A paper tape reader/punch
TTI,TTO KSR 33 console terminal
LPT Type 647E line printer
CLK integral real-time clock
RF RF09/RS09 fixed-head disk
MT TC59/TU10 magnetic tape
PDP-15 CPU PDP-15 CPU with 32KW of memory
- KE15 extended arithmetic element (EAE)
- KF15 power detection
- KM15 memory protection
PTR,PTP PC15 paper tape reader/punch
TTI,TTO KSR 35 console terminal
LPT LP15 line printer
CLK integral real-time clock
RP RP15/RP02 disk pack
RF RF15/RS09 fixed-head disk
MT TC59/TU10 magnetic tape
The 18b PDP simulators implement several unique stop conditions:
- an unimplemented instruction is decoded, and register
STOP_INST is set
- more than XCTMAX nested executes are detected during
instruction execution
The 18b PDP loader supports RIM format tapes. The DUMP command is not
implemented.
8.1 CPU
The only CPU options are the presence of the EAE and the size of main memory.
SET CPU EAE enable EAE
SET CPU NOEAE disable EAE
SET CPU 4K set memory size = 4K
SET CPU 8K set memory size = 8K
SET CPU 12K set memory size = 12K
SET CPU 16K set memory size = 16K
SET CPU 20K set memory size = 20K
SET CPU 24K set memory size = 24K
SET CPU 28K set memory size = 28K
SET CPU 32K set memory size = 32K
SET CPU 48K set memory size = 48K
SET CPU 64K set memory size = 64K
SET CPU 80K set memory size = 80K
SET CPU 96K set memory size = 96K
SET CPU 112K set memory size = 112K
SET CPU 128K set memory size = 128K
Memory sizes greater than 8K are only available on the PDP-7, PDP-9, and
PDP-15; memory sizes greater than 32KW are only available on the PDP-15.
If memory size is being reduced, and the memory being truncated contains
non-zero data, the simulator asks for confirmation. Data in the truncated
portion of memory is lost. Initial memory size is 8K for the PDP-4, 32K
for the PDP-7 and PDP-9, and 128K for the PDP-15.
CPU registers include the visible state of the processor as well as the
control registers for the interrupt system.
system name size comments
all PC addr program counter
7,9 PC 15 program counter
15 PC 17 program counter
all AC 18 accumulator
7,9,15 MQ 18 multiplier-quotient
7,9,15 SC 6 shift counter
7,9,15 EAE_AC_SIGN 1 EAE AC sign
all L 1 link
7,9 EXTM 1 extend mode
15 BANKM 1 bank mode
7 TRAPM 1 trap mode
9,15 USMD 1 user mode
9,15 USMDBUF 1 user mode buffer
9,15 BR addr memory protection bounds
7,9,15 TRAPP 1 trap pending
9,15 NEXM 1 non-existent memory violation
9,15 PRVN 1 privilege violation
7,9 EMIRP 1 EMIR instruction pending
9,15 RESTP 1 DBR or RES instruction pending
15 XR 18 index register
15 LR 18 limit register
all SR 18 front panel switches
all INT 32 interrupt requests
all IORS 18 IORS register
all ION 1 interrupt enable
all ION_DELAY 2 interrupt enable delay
all OLDPC addr PC prior to last transfer
all STOP_INST 1 stop on undefined instruction
all BREAK 18 breakpoint address (777777 to disable)
all WRU 8 interrupt character
"addr" signifies the address width of the system (13b for the PDP-4, 15b for
the PDP-7 and PDP-9, 17b for the PDP-15).
8.2 Programmed I/O Devices
8.2.1 Paper Tape Reader (PTR)
The paper tape reader (PTR) reads data from a disk file. The POS
register specifies the number of the next data item to be read. Thus,
by changing POS, the user can backspace or advance the reader.
The paper tape reader implements these registers:
name size comments
BUF 8 last data item processed
INT 1 interrupt pending flag
DONE 1 device done flag
ERR 1 error flag (PDP-9, PDP-15 only)
POS 31 position in the input file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape
end of file 1 report error and stop
0 out of tape
OS I/O error x report error and stop
8.2.2 Paper Tape Punch (PTP)
The ppaper tape punch (PTP) writes data to a disk file. The POS
register specifies the number of the next data item to be written.
Thus, by changing POS, the user can backspace or advance the punch.
The paper tape punch implements these registers:
name size comments
BUF 8 last data item processed
INT 1 interrupt pending flag
DONE 1 device done flag
ERR 1 error flag (PDP-9, PDP-15 only)
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape or paper
OS I/O error x report error and stop
8.2.3 Terminal Input (TTI)
The terminal input (TTI) reads from the controling console port. The
input has one option, UC; when set, it automatically converts lower
case input to upper case.
The terminal input implements these registers:
name size comments
BUF 8 last data item processed
INT 1 interrupt pending flag
DONE 1 device done flag
POS 31 number of characters input
TIME 24 keyboard polling interval
8.2.4 Terminal Output (TTO)n backspace or advance these devices.
The terminal output (TTO) writes to the controling console port. It
implements these registers:
name size comments
BUF 8 last data item processed
INT 1 interrupt pending flag
DONE 1 device done flag
POS 31 number of chararacters output
TIME 24 time from I/O initiation to interrupt
8.2.5 Line Printer (LPT)
The line printer (LPT) writes data to a disk file. The POS register
specifies the number of the next data item to be written. Thus,
by changing POS, the user can backspace or advance the printer.
The PDP-4 used a Type 62 printer controller, with these registers:
name size comments
BUF 8 last data item processed
INT 1 interrupt pending flag
DONE 1 device done flag
SPC 1 spacing done flag
BPTR 6 print buffer pointer
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
The PDP-7 and PDP-7 used a Type 647 printer controller, with these
registers:
name size comments
BUF 8 last data item processed
INT 1 interrupt pending flag
DONE 1 device done flag
ENABLE 1 interrupt enable (PDP-9 only)
ERR 1 error flag
BPTR 7 print buffer pointer
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
The PDP-15 used an LP15 printer controller, with these registers:
name size comments
STA 18 status register
MA 18 DMA memory address
INT 1 interrupt pending flag
ENABLE 1 interrupt enable
LCNT 8 line counter
BPTR 7 print buffer pointer
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
For all three models, error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape or paper
OS I/O error x report error and stop
8.2.6 Real-Time Clock (CLK)
The real-time clock (CLK) implements these registers:
name size comments
INT 1 interrupt pending flag
DONE 1 device done flag
ENABLE 1 clock enable
TIME 24 clock frequency
8.3 RP15/RP02 Disk Pack (RP)
RP15 options include the ability to make units write enabled or write locked:
SET RPn LOCKED set unit n write locked
SET RPn ENABLED set unit n write enabled
Units can also be REMOVEd or ADDed to the configuration.
The RP15 implements these registers:
name size comments
STA 18 status A
STB 18 status B
DA 18 disk address
MA 18 current memory address
WC 18 word count
INT 1 interrupt pending flag
BUSY 1 control busy flag
STIME 24 seek time, per cylinder
RTIME 24 rotational delay
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 disk not ready
end of file x assume rest of disk is zero
OS I/O error x report error and stop
8.4 Type 24 Serial Drum (DRM)
The serial drum (DRM) implements these registers:
name size comments
DA 9 drum address (sector number)
MA 15 current memory address
INT 1 interrupt pending flag
DONE 1 device done flag
ERR 1 error flag
WLK 32 write lock switches
TIME 24 rotational latency, per word
STOP_IOE 1 stop on I/O error
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 disk not ready
Drum data files are buffered in memory; therefore, end of file and OS
I/O errors cannot occur.
8.5 RF09/RF15/RS09 Fixed Head Disk (RF)
The RF09/RF15 implements these registers:
name size comments
STA 18 status
DA 21 current disk address
MA 18 memory address (in memory)
WC 18 word count (in memory)
BUF 18 data buffer (diagnostic only)
INT 1 interrupt pending flag
WLK0..7 16 write lock switches for disks 0..7
TIME 24 rotational delay, per word
BURST 1 burst flag
STOP_IOE 1 stop on I/O error
The RF09/RF15 is a three-cycle data break device. If BURST = 0, word
transfers are scheduled individually; if BURST = 1, the entire transfer
occurs in a single data break.
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 disk not ready
RF15/RF09 data files are buffered in memory; therefore, end of file and OS
I/O errors cannot occur.
8.6 TC59/TU10 Magnetic Tape (MT)
Magnetic tape options include the ability to make units write enabled or
or write locked.
SET MTn LOCKED set unit n write locked
SET MTn ENABLED set unit n write enabled
Units can also be REMOVEd or ADDed to the configuration.
The magnetic tape controller implements these registers:
name size comments
CMD 18 command
STA 18 main status
MA 18 memory address (in memory)
WC 18 word count (in memory)
INT 1 interrupt pending flag
STOP_IOE 1 stop on I/O error
TIME 24 record delay
UST0..7 24 unit status, units 0..n
POS0..7 31 position, units 0..n
Error handling is as follows:
error processed as
not attached tape not ready
end of file (read or space) end of physical tape
(write) ignored
OS I/O error report error and stop
8.7 Symbolic Display and Input
The 18b PDP simulators implement symbolic display and input. Display is
controlled by command line switches:
-a display as ASCII character
-c display as (sixbit) character string
-m display instruction mnemonics
The PDP-15 also recognizes an additional switch:
-p display as packed ASCII (five 7b ASCII
characters in two 18b words)
Input parsing is controlled by the first character typed in or by command
line switches:
' or -a ASCII character
" or -c three character sixbit string
alphabetic instruction mnemonic
numeric octal number
The PDP-15 also recognizes an additional input mode:
# or -p five character packed ASCII string in
two 18b words
Instruction input uses standard 18b PDP assembler syntax. There are six
instruction classes: memory reference, EAE, index (PDP-15 only), IOT,
operate, and LAW.
Memory reference instructions have the format
memref {I/@} address{,X}
where I (PDP-4, PDP-7, PDP-9) /@ (PDP-15) signifies indirect reference,
and X signifies indexing (PDP-15 in page mode only). The address is an
octal number in the range 0 - 017777 (PDP-4, PDP-7, PDP-9, and PDP-15 in
bank mode) or 0 - 07777 (PDP-15 in page mode).
IOT instructions consist of single mnemonics, eg, KRB, TLS. IOT instructions
may be or'd together
iot iot iot...
IOT's may also include the number 10, signifying clear the accumulator
iot 10
The simulator does not check the legality of IOT combinations. IOT's for
which there is no opcode may be specified as IOT n, where n is an octal
number in the range 0 - 07777.
EAE instructions have the format
eae {+/- shift count}
EAE instructions may be or'd together
eae eae eae...
The simulator does not check the legality of EAE combinations. EAE's for
which there is no opcode may be specified as EAE n, where n is an octal
number in the range 0 - 037777.
Index instructions (PDP-15 only) have the format
index {immediate}
The immediate, if allowed, must be in the range of -0400 to +0377.
Operate instructions have the format
opr opr opr...
The simulator does not check the legality of the proposed combination. The
operands for MUY and DVI must be deposited explicitly.
Finally, the LAW instruction has the format
LAW immediate
where immediate is in the range of 0 to 017777.
8.8 Character Sets
The PDP-4's console was an ASR-28 Teletype; its character encoding was
Baudot. The PDP-4's line printer used a modified Hollerith character
set. The PDP-7's and PDP-9's consoles were KSR-33 Teletypes; their
character sets were basically ASCII. The PDP-7's and PDP-9's line
printers used sixbit encoding (ASCII codes 040 - 0137 masked to six
bits). The PDP-15's I/O devices were all ASCII. The following table
provides equivalences between ASCII characters and the PDP-4's I/O devices.
In the console table, FG stands for figures (upper case).
PDP-4 PDP-4
ASCII console line printer
000 - 006 none none
bell FG+024 none
010 - 011 none none
lf 010 none
013 - 014 none none
cr 002 none
016 - 037 none none
space 004 000
! FG+026 none
" FG+021 none
# FG+005 none
$ FG+062 none
% none none
& FG+013 none
' FG+032 none
( FG+036 057
) FG+011 055
* none 072
+ none 074
, FG+006 033
- FG+030 054
. FG+007 073
/ FG+027 021
0 FG+015 020
1 FG+035 001
2 FG+031 002
3 FG+020 003
4 FG+012 004
5 FG+001 005
6 FG+025 006
7 FG+034 007
8 FG+014 010
9 FG+003 011
: FG+016 none
; FG+017 none
< none 034
= none 053
> none 034
? FG+023 037
@ none {MID DOT} 040
A 030 061
B 023 062
C 016 063
D 022 064
E 020 065
F 026 066
G 013 067
H 005 070
I 014 071
J 032 041
K 036 042
L 011 043
M 007 044
N 006 045
O 003 046
P 015 047
Q 035 050
R 012 051
S 024 022
T 001 023
U 034 024
V 017 025
W 031 026
X 027 027
Y 025 030
Z 021 031
[ none none
\ none {OVERLINE} 056
] none none
^ none {UP ARROW} 035
_ none UC+040
0140 - 0177 none none
9. IBM 1401 Features
The IBM 1401 simulator is configured as follows:
device simulates
name(s)
CPU IBM 1401 CPU with 16K of memory
CDR,CDP IBM 1402 card reader/punch
LPT IBM 1403 line printer
INQ IBM 1407 inquiry terminal
MT IBM 729 7-track magnetic tape controller with six drives
The IBM 1401 simulator implements many unique stop conditions. On almost
any kind of error the simulator stops:
unimplemented opcode
reference to non-existent memory
reference to non-existent device
no word mark under opcode
invalid A address
invalid B address
invalid instruction length
invalid modifier character
invalid branch address
invalid magtape unit number
invalid magtape record length
write to locked magtape drive
skip to unpunched carriage control tape channel
card reader hopper empty
address register wrap-around
single character A field in MCE
single character B field in MCE
hanging $ in MCE with EPE enabled
I/O check with I/O stop switch set
The LOAD and DUMP commands are not implemented.
9.1 CPU
The CPU options include a number of special features and the size of main
memory. Note that the Modify Address special feature is always included
when memory size is greater than 4K.
SET CPU XSA enable advanced programming special feature
SET CPU NOXSA disable advanced programming
SET CPU HLE enable high/low/equal special feature
SET CPU NOHLE disable high/low/equal
SET CPU BBE enable branch on bit equal special feature
SET CPU NOBBE disable branch on bit equal
SET CPU MR enable move record special feature
SET CPU NOMR disable move record
SET CPU EPE enable extended print edit special feature
SET CPU NOEPE disable extended print edit
SET CPU 4K set memory size = 4K
SET CPU 8K set memory size = 8K
SET CPU 12K set memory size = 12K
SET CPU 16K set memory size = 16K
If memory size is being reduced, and the memory being truncated contains
non-zero data, the simulator asks for confirmation. Data in the truncated
portion of memory is lost. Initially, memory size is 16K, and all special
features are enabled.
Memory is implemented as 7 bit BCD characters, as follows:
6 5 4 3 2 1 0
word B bit A bit 8 4 2 1
mark <-- zone --> <-------- digit -------->
In BCD, the decimal digits 0-9 are (octal) values 012, 001, 002, 003, 004,
005, 006, 007, 010, 011, respectively. Signs are encoded in the zone bits,
with 00, 01, and 11 being positive, and 10 being negative.
CPU registers include the visible state of the processor. The 1401 has no
interrupt system.
name size comments
IS 14 instruction storage address register (PC)
AS 14 A storage address register
BS 14 B storage address register
ASERR 1 AS invalid flag
BSERR 1 BS invalid flag
SSA 1 sense switch A
SSB 1 sense switch B
SSC 1 sense switch C
SSD 1 sense switch D
SSE 1 sense switch E
SSF 1 sense switch F
SSG 1 sense switch G
EQU 1 equal compare indicator
UNEQ 1 unequal compare indicator
HIGH 1 high compare indicator
LOW 1 low compare indicator
OVF 1 overflow indicator
IOCHK 1 I/O check switch
PRCHK 1 process check switch
OLDIS 1 IS prior to last branch
BREAK 17 breakpoint address (1000000 to disable)
WRU 8 interrupt character
9.2 1402 Card Reader/Punch (CDR, CDP, STKR)
The IBM 1402 card/reader punch is simulated as three independent devices:
the card reader (CDR), the card punch (CDP), and the reader and punch
stackers (STKR). STRK units 0, 1, 2, and 4 correspond to the reader
normal stacker, reader stacker 1, shared stacker 2/8, and punch stacker
4, respectively.
The card reader reads data from disk files, while the punch and stackers
write data to disk files. Cards are simulated as ASCII text lines with
terminating newlines; column binary is not supported. For each unit,
the POS register specifies the number of the next data item to be read or
written. Thus, by changing POS, the user can backspace or advance these
devices.
The reader/punch registers are:
device name size comments
CDR LAST 1 last card indicator
ERR 1 error indicator
S1 1 stacker 1 select flag
S2 1 stacker 2 select flag
POS 31 position
TIME 24 delay window for stacker select
CDP ERR 1 error indicator
S4 1 stacker 4 select flag
S8 1 stacker 8 select flag
STKR POS0 31 position, normal reader stack
POS1 31 position, reader stacker 1
POS2 31 position, shared stacker 2/8
POS4 31 position, punch stacker 4
Error handling is as follows:
device error processed as
reader end of file if SSA set, set LAST indicator
on next Read, report error and stop
reader,punch not attached report error and stop
OS I/O error print error message
if IOCHK set, report error and stop
otherwise, set ERR indicator
stacker not attached ignored
OS I/O error print error message
if IOCHK set, report error and stop
9.3 1403 Line Printer (LPT)
The IBM 1403 line printer (LPT) writes its data, converted to ASCII, to
a disk file. The line printer supports three different print character
sets or "chains":
SET LPT PCF full 64 character chain
SET LPT PCA 48 character business chain
SET LPT PCH 48 character FORTRAN chain
In addition, the line printer can be programmed with a carriage control
tape. The LOAD command loads a new carriage control tape:
LOAD <file> load carriage control tape file
The format of a carriage control tape consists of multiple lines. Each
line contains an optional repeat count, enclosed in parentheses, optionally
followed by a series of column numbers separated by commas. Column numbers
must be between 1 and 12; a column number of zero denotes top of form. The
following are all legal carriage control specifications:
<blank line> no punch
(5) 5 lines with no punches
1,5,7,8 columns 1, 5, 7, 8 punched
(10)2 10 lines with column 2 punched
1,0 column 1 punched; top of form
The default form is 66 lines long, with column 1 and the top of form mark
on line 1, and the rest blank.
The line printer registers are:
name size comments
LINES 8 number of newlines after next print
LFLAG 1 carriage control flag (1 = skip, 0 = space)
CCTP 8 carriage control tape pointer
CCTL 8 carriage control tape length (read only)
ERR 1 error indicator
POS 31 position
Error handling is as follows:
error processed as
not attached report error and stop
OS I/O error print error message
if IOCHK set, report error and stop
otherwise, set ERR indicator
9.4 1407 Inquiry Terminal (INQ)
The IBM 1407 inquiry terminal (INQ) is a half-duplex console. It polls
the controling keyboard of the simulator periodically for inquiry requests.
The inquiry terminal registers are:
name size comments
INQC 7 inquiry request character (initially ESC)
INR 1 inquiry request indicator
INC 1 inquiry cleared indicator
TIME 24 polling interval
When the 1401 CPU requests input from the keyboard, the message [Enter]
is printed out, followed by a new line. The CPU hangs waiting for input
until either the return/enter key is pressed, or the inquiry request
character is typed in. The latter cancels the type-in and sets INC.
The inquiry terminal has no errors.
9.5 729 Magnetic Tape (MT)
The magnetic tape controller supports six drives, numbered 1 through 6.
Magnetic tape options include the ability to make units write enabled or
or write locked.
SET MTn LOCKED set unit n write locked
SET MTn ENABLED set unit n write enabled
Units can also be REMOVEd or ADDed to the configuration.
The magnetic tape controller implements these registers:
name size comments
END 1 end of file indicator
ERR 1 error indicator
PAR 1 parity error indicator
POS1..6 31 position, drives 1..6
Error handling is as follows:
error processed as
not attached report error and stop
end of file (read or space) end of physical tape
(write) ignored
OS I/O error print error message
if IOCHK set, report error and stop
otherwise, set ERR indicator
9.6 Symbolic Display and Input
The IBM 1401 simulator implements symbolic display and input. Display is
controlled by command line switches:
-c display as single character
(BCD for CPU and MT, ASCII for others)
-s display as wordmark terminated BCD string
(CPU only)
-m display instruction mnemonics
(CPU only)
In a CPU character display, word marks are denoted by ~.
Input parsing is controlled by the first character typed in or by command
line switches:
' or " or -c or -s characters (BCD for CPU and MT, ASCII
for others)
alphabetic instruction mnemonic
numeric octal number
Instruction input is free format, with spaces separating fields. There
are six instruction formats: 1, 2, 4, 5, 7, and 8 characters:
1 character opcode
2 character opcode 'modifier
4 character opcode address
5 character opcode address 'modifier
7 character opcode address address
8 character opcode address address 'modifier
Addresses are always decimal, except for special I/O addresses in the A
field, which may be specified as %xy, where x denotes the device and y
the unit number.
For the CPU, string input may encompass multiple characters. A word mark
is denoted by ~ and must precede the character to be marked. All other
devices can only accept single character input, without word marks.
9.7 Character Sets
The IBM 1401 used a 6b character code called BCD (binary coded decimal).
Some of the characters have no equivalent in ASCII and require different
representations:
BCD ASCII IBM 1401 print
code representation character chains
00 space
01 1
02 2
03 3
04 4
05 5
06 6
07 7
10 8
11 9
12 0
13 # = in H chain
14 @ ' in H chain
15 : blank in A, H chains
16 > blank in A, H chains
17 ( tape mark blank in A, H chains
20 ^ alternate blank blank in A, H chains
21 /
22 S
23 T
24 U
25 V
26 W
27 X
30 Y
31 Z
32 ' record mark
33 ,
34 % ( in H chain
35 = word mark blank in A, H chains
36 \ blank in A, H chains
37 + blank in A, H chains
40 -
41 J
42 K
43 L
44 M
45 N
46 O
47 P
50 Q
51 R
52 !
53 $
54 *
55 ] blank in A, H chains
56 ; blank in A, H chains
57 _ delta blank in A, H chains
60 &
61 A
62 B
63 C
64 D
65 E
66 F
67 G
70 H
71 I
72 ?
73 .
74 ) lozenge
75 [ blank in A, H chains
76 < blank in A, H chains
77 " group mark blank in A, H chains
10. HP2100 Features
The HP2100 simulator is configured as follows:
device simulates
name(s)
CPU 2116, 2100, or 21MX CPU with 32KW memory
DMA0, DMA1 dual channel DMA controller
PTR,PTP paper tape reader/punch
TTY console terminal
LPT LE8E line printer
CLK 12639C time base generator
DP 12557A cartridge disk controller with four drives
MT 12559 magnetic tape controller with one drives
The HP2100 simulator implements several unique stop conditions:
- decode of an undefined instruction, and STOP_INST is et
- reference to an undefined I/O device, and STOP_DEV is set
- more than INDMAX indirect references are detected during
memory reference address decoding
The HP2100 loader supports standard absolute binary format. The DUMP
command is not implemented.
10.1 CPU
CPU options include choice of instruction set and memory size.
SET CPU 2116 2116 instructions
SET CPU 2100 2100 instructions
SET CPU 21MX 21MX instructions
SET CPU 4K set memory size = 4K
SET CPU 8K set memory size = 8K
SET CPU 16K set memory size = 16K
SET CPU 24K set memory size = 24K
SET CPU 32K set memory size = 32K
If memory size is being reduced, and the memory being truncated contains
non-zero data, the simulator asks for confirmation. Data in the truncated
portion of memory is lost. Initial memory size is 32K.
CPU registers include the visible state of the processor as well as the
control registers for the interrupt system.
name size comments
P 15 program counter
A 16 A register
B 16 B register
X 16 X index register (21MX)
Y 16 Y index register (21MX)
S 16 switch/display register
E 1 extend flag
O 1 overflow flag
ION 1 interrupt enable flag
ION_DEFER 1 interrupt defer flag
IADDR 6 most recent interrupting device
MPCTL 1 memory protection enable (2100, 21MX)
MPFLG 1 memory protection flag (2100, 21MX)
MPFBF 1 memory protection flag buffer (2100, 21MX)
MFENCE 15 memory protection fence (2100, 21MX)
MADDR 16 memory protection error address (2100, 21MX)
STOP_INST 1 stop on undefined instruction
STOP_DEV 1 stop on undefined device
INDMAX 1 indirect address limit
OLDP 15 PC prior to last JMP, JSB, or interrupt
BREAK 16 breakpoint address (177777 to disable)
WRU 8 interrupt character
10.2 DMA Controllers
The HP2100 includes two DMA channel controllers (DMA0 and DMA1). Each
DMA channel has the following visible state:
name size comments
CMD 1 channel enabled
CTL 1 interrupt enabled
FLG 1 channel ready
FBF 1 channel ready buffer
CW1 1 command word 1
CW2 1 command word 2
CW3 1 command word 3
10.3 Variable Device Assignments
On the HP2100, I/O device take their device numbers from the backplane
slot they are plugged into. Thus, device number assignments vary
considerably from system to system, and software package to software
package. The HP2100 simulator supports dynamic device reassignment
with the command:
SET <controller> DEVNO
This initiates a dialog that displays the current device number and
allows the user to assign a new one:
Device number: old <new>(cr)
The new device number must be in the range 010..077 (octal) and must
not be currently assigned to another device. For devices with two
device numbers, only the lower numbered device number can be changed;
the higher is automatically set to the lower + 1.
10.4 Programmed I/O Devices
10.4.1 Paper Tape Reader (PTR)
The paper tape reader (PTR) reads data from a disk file. The POS
register specifies the number of the next data item to be read.
Thus, by changing POS, the user can backspace or advance the reader.
The paper tape reader supports the BOOT command. BOOT PTR copies the
absolute binary loader into memory and starts it running.
The paper tape reader implements these registers:
name size comments
BUF 8 last data item processed
CTL 1 device/interrupt enable
FLG 1 device ready
FBF 1 device ready buffer
POS 31 position in the input file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
DEVNO 6 current device number (read only)
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape
end of file 1 report error and stop
0 out of tape or paper
OS I/O error x report error and stop
10.4.2 Paper Tape Punch (PTP)
The paper tape punch (PTP) writes data to a disk file. The POS
register specifies the number of the next data item to be written.
Thus, by changing POS, the user can backspace or advance the punch.
The paper tape punch implements these registers:
name size comments
BUF 8 last data item processed
CTL 1 device/interrupt enable
FLG 1 device ready
FBF 1 device ready buffer
POS 31 position in the output file
TIME 24 time from I/O initiation to interrupt
STOP_IOE 1 stop on I/O error
DEVNO 6 current device number (read only)
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape
OS I/O error x report error and stop
10.4.3 Console Terminal (TTY)
The console terminal has three units: keyboard (unit 0), printer
(unit 1), and punch (unit 2). The keyboard reads from, and the
printer writes to, the controlling console port. The punch writes
to a disk file. The keyboard has one option, UC; when set, it
automatically converts lower case input to upper case. This is on
by default.
The terminal implements these registers:
name size comments
BUF 8 last data item processed
MODE 16 mode
CTL 1 device/interrupt enable
FLG 1 device ready
FBF 1 device ready buffer
KPOS 31 number of characters input
KTIME 24 keyboard polling interval
TPOS 31 number of characters printed
TTIME 24 time from I/O initiation to interrupt
PPOS 31 position in the punch output file
STOP_IOE 1 punch stop on I/O error
DEVNO 6 current device number (read only)
Error handling for the punch is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape
OS I/O error x report error and stop
10.4.4 12653A Line Printer (LPT)
The line printer (LPT) writes data to a disk file. The POS register
specifies the number of the next data item to be written. Thus,
by changing POS, the user can backspace or advance the printer.
The line printer implements these registers:
name size comments
BUF 8 last data item processed
CTL 1 device/interrupt enable
FLG 1 device ready
FBF 1 device ready buffer
POS 31 position in the output file
CTIME 24 time between characters
PTIME 24 time for a print operation
STOP_IOE 1 stop on I/O error
DEVNO 6 current device number (read only)
Error handling is as follows:
error STOP_IOE processed as
not attached 1 report error and stop
0 out of tape or paper
OS I/O error x report error and stop
10.4.5 12639C Time Base Generator (CLK)
The time base generator (CLK) implements these registers:
name size comments
SEL 3 time base select
CTL 1 device/interrupt enable
FLG 1 device ready
FBF 1 device ready buffer
ERR 1 error flag
TIME0..TIME7 31 clock intervals, select = 0..7
DEVNO 6 current device number (read only)
10.5 12559C Cartridge Disk (DP)
The 12559C cartridge disk has two separate devices, a data channel and
a device controller. The data channel includes a 128-word (one sector)
buffer for reads and writes. The device controller includes the four
disk drives. Disk drives can be REMOVEd or ADDed to the configuration.
The data channel implements these registers:
name size comments
IBUF 16 input buffer
OBUF 16 output buffer
BPTR 7 sector buffer pointer
CMD 1 channel enabled
CTL 1 interrupt enabled
FLG 1 channel ready
FBF 1 channel ready buffer
DEVNO 6 current device number (read only)
The device controller implements these registers:
name size comments
OBUF 16 output buffer
BUSY 3 busy (unit #, + 1, of active unit)
RARC 8 record address register cylinder
RARH 2 record address register head
RARS 4 record address register sector
CNT 5 check record count
CMD 1 controller enabled
CTL 1 interrupt enabled
FLG 1 controller ready
FBF 1 controller ready buffer
EOC 1 end of cylinder pending
CTIME 24 command delay time
STIME 24 seek delay time, per cylinder
XTIME 24 interword transfer time
STA0 16 drive 0 status
STA1 16 drive 1 status
STA2 16 drive 2 status
STA3 16 drive 3 status
DEVNO 6 current device number (read only)
Error handling is as follows:
error processed as
not attached disk not ready
end of file assume rest of disk is zero
OS I/O error report error and stop
10.6 12557 Magnetic Tape (MT)
Magnetic tape options include the ability to make the unit write enabled
or write locked.
SET MT LOCKED set unit write locked
SET MT ENABLED set unit write enabled
The 12557 mag tape drive has two separate devices, a data channel and
a device controller. The data channel includes a maximum record sized
buffer for reads and writes. The device controller includes the tape
unit
The data channel implements these registers:
name size comments
FLG 1 channel ready
BPTR 16 buffer pointer (reads and writes)
BMAX 16 buffer size (writes)
DEVNO 6 current device number (read only)
The device controller implements these registers:
name size comments
FNC 8 current function
STA 9 tape status
BUF 8 buffer
BUSY 3 busy (unit #, + 1, of active unit)
CTL 1 interrupt enabled
FLG 1 controller ready
FBF 1 controller ready buffer
DTF 1 data transfer flop
FSVC 1 first service flop
POS 31 magtape position
CTIME 24 command delay time
XTIME 24 interword transfer delay time
STOP_IOE 1 stop on I/O error
DEVNO 6 current device number (read only)
Error handling is as follows:
error processed as
not attached tape not ready
end of file (read or space) end of physical tape
(write) ignored
OS I/O error report error and stop
10.7 Symbolic Display and Input
The HP2100 simulator implements symbolic display and input. Display is
controlled by command line switches:
-a display as ASCII character
-c display as two character string
-m display instruction mnemonics
Input parsing is controlled by the first character typed in or by command
line switches:
' or -a ASCII character
" or -c two character sixbit string
alphabetic instruction mnemonic
numeric octal number
Instruction input uses standard HP2100 assembler syntax. There are seven
instruction classes: memory reference, I/O, shift, alter skip, extended
shift, extended memory reference, extended two address reference.
Memory reference instructions have the format
memref {C/Z} address{,I}
where I signifies indirect, C a current page reference, and Z a zero page
reference. The address is an octal number in the range 0 - 077777; if C or
Z is specified, the address is a page offset in the range 0 - 01777. Normally,
C is not needed; the simulator figures out from the address what mode to use.
However, when referencing memory outside the CPU (eg, disks), there is no
valid PC, and C must be used to specify current page addressing.
IOT instructions have the format
io device{,C}
where C signifies that the device flag is to be cleared. The device is an
octal number in the range 0 - 77.
Shift and alter/skip instructions have the format
sub-op sub-op sub-op...
The simulator checks that the combination of sub-opcodes is legal.
Extended shift instructions have the format
extshift count
where count is an octal number in the range 1 - 020.
Extended memory reference instructions have the format
extmemref address{,I}
where I signifies indirect addressing. The address is an octal number in
the range 0 - 077777.
Extended two address instructions have the format
ext2addr addr1{,I},addr2{,I}
where I signifies indirect addressing. Both address 1 and address 2 are
octal numbers in the range 0 - 077777.
11. Interdata 4 Features
The Interdata 4 simulator is not fully debugged. Lack of documentation
and software makes checkout very difficult. The simulator is included in
the hopes that a fellow enthusiast may be able to provide software or
additional documentation to facilitate further debug.
The Interdata 4 simulator is configured as follows:
device simulates
name(s)
CPU Interdata 4 CPU with 64KB memory
PT paper tape reader/punch
TT console terminal
The Interdata 4 simulator implements one unique stop condition:
- decode of an undefined instruction, and STOP_INST is set
The LOAD and DUMP command are not implemented.
11.1 CPU
The only CPU options are memory size:
SET CPU 8K set memory size = 8KB
SET CPU 16K set memory size = 16KB
SET CPU 24K set memory size = 24KB
SET CPU 32K set memory size = 32KB
SET CPU 48K set memory size = 48KB
SET CPU 64K set memory size = 64KB
If memory size is being reduced, and the memory being truncated contains
non-zero data, the simulator asks for confirmation. Data in the truncated
portion of memory is lost. Initial memory size is 64KB.
CPU registers include the visible state of the processor as well as the
control registers for the interrupt system.
name size comments
PC 16 program counter
R0..RF 16 general registers
F0, F2..FE 32 floating point registers
PSW 16 processor status word
CC 4 condition codes, PSW<12:15>
SR 16 switch register
DR 16 display register low 16 bits
DR1 16 display register high 16 bits
DRMOD 1 display mode
DRPOS 2 display pointer position
SRPOS 1 switch pointer position
IRQ0..IRQ7 32 interrupt requests
IEN0..IEN7 32 interrupt enables
STOP_INST 1 stop on undefined instruction
OLDPC 16 PC prior to last branch or interrupt
BREAK 17 breakpoint address (377777 to disable)
WRU 8 interrupt character
11.2 Paper Tape Reader/Punch (PT)
The paper tape reader and punch (PT units 0 and 1) read data from or
write data to disk files. The RPOS and PPOS registers specify the
number of the next data item to be read and written, respectively.
Thus, by changing RPOS or PPOS, the user can backspace or advance
these devices.
The paper tape reader supports the BOOT command. BOOT PTR copies the
so-called '50 loader' into memory and starts it running.
The paper tape controller implements these registers:
name size comments
RBUF 8 reader buffer
RPOS 31 reader position in the input file
RTIME 24 time from reader start to interrupt
RSTOP_IOE 1 reader stop on I/O error
PBUF 8 punch buffer
PPOS 31 punch position in the output file
PTIME 24 time from punch start to interrupt
PSTOP_IOE 1 punch stop on I/O error
IREQ 1 paper tape interrupt request
IENB 1 paper tape interrupt enable
RUN 1 paper tape running
SLEW 1 paper tape reader slew mode
BUSY 1 paper tape busy
RW 1 paper tape read/write mode
Error handling is as follows:
type error STOP_IOE processed as
in,out not attached 1 report error and stop
0 out of tape
in end of file 1 report error and stop
0 out of tape
in,out OS I/O error x report error and stop
11.3 Teletype (TT)
The teletype reads and writes to the controlling console port. The
keyboard has one option, UC; when set, it automatically converts lower
case input to upper case. This is on by default.
name size comments
KBUF 8 keyboard buffer
KPOS 31 number of characters output
KTIME 24 keyboard polling interval
TBUF 8 output buffer
TPOS 31 number of characters output
TTIME 24 time from output start to interrupt
IREQ 1 teletype interrupt request
IENB 1 teletype interrupt enable
HDPX 1 teletype half-duplex
BUSY 1 teletype busy
RW 1 teletype read/write mode
11.4 Symbolic Display and Input
The Interdata 4 simulator implements symbolic display and input. Display is
controlled by command line switches:
-a display as ASCII character
-c display as two character string
-m display instruction mnemonics
Input parsing is controlled by the first character typed in or by command
line switches:
' or -a ASCII character
" or -c two character sixbit string
alphabetic instruction mnemonic
numeric octal number
Instruction input uses standard Interdata 4 assembler syntax. There are
four instruction classes: register, memory, register-register, register-
memory.
Register instructions have the format
rop regnum
where the register number is a hex digit, optionally preceded by R,
between 0 and F.
Memory instructions have the format
mop address{(index)}
where address is a hex number between 0 and 0xFFFF, and the index register
is a hex digit, optinally preceded by R, between 0 and F.
Register-register instructions have the format
rrop regnum,regnum
where the register numbers are hex digits, optionally preceded by R,
between 1 and F.
Register-memory instructions have the format
rmop regnum,address{(index)}
where the register number is a hex digit, optionally preceded by R,
between 0 and F, the address is a hex number between 0 and 0xFFFF, and
the index register is a hex digit, optionally preceded by R, between
1 and F.
Appendix 1: File Representations
All file representations are little endian. On big endian hosts, the
simulator automatically performs any required byte swapping.
1. Hard Disks
Hard disks are represented as unstructured binary files of 16b data items for
the 12b and 16b simulators, of 32b data items for the 18b and 32b simulators,
and 64b for the 36b simulators.
2. Floppy Disks
PDP-8 and PDP-11 floppy disks are represented as unstructured binary files
of 8b data items. They are nearly identical to the floppy disk images for
Doug Jones' PDP-8 simulator but lack the initial 256 byte header. A utility
for converting between the two formats is easily written.
3. Magnetic Tapes
Magnetic tapes are represented as unstructured binary files of 8b data
items. Each record consists of a 32b record header, in little endian
format, followed by n 8b bytes of data, followed by a repeat of the 32b
record header. The high order bit of the record header is used as an
error flag; the remaining 31b are the byte count of the record. If
the byte count is odd, the record is padded to even length; the pad
byte is undefined.
Magnetic tapes are endian independent and consistent across simulator
families. A magtape produced by the Nova simulator will appear to
have its 16b words byte swapped if read by the PDP-11 simulator.
4. Line Printers
Line printer output is represented by an ASCII file of lines separated by
the newline character. Overprinting is represented by a line ending in
return rather than newline.
Appendix 2: Sample Software
1. PDP-8
1.1 ESI-X
ESI-X is an interactive program for technical computation. It can
execute both immediate commands and stored programs (like BASIC). ESI-X
is provided as both source and as a binary loader format paper-tape
image. For more information see the documentation included with the
program. My thanks to Dave Waks, who wrote the program, and to Paul
Pierce and Tim Litt, who recovered the source from its archival medium.
To load and run ESI-X:
sim> load esix.bin
sim> run 5400
_TYPE 2+2.
2+2 = 4
1.2 FOCAL69
FOCAL69 is an interactive program for technical computations. It can
execute both immediate commands and stored programs (like BASIC). FOCAL69
is provided as a binary loader format paper-tape image. To load and
run FOCAL69:
sim> load focal69.bin
sim> run 200
*TYPE 2+2
= 4.000*
1.3 PDP-8 OS/8
OS/8 is the PDP-8's mass storage-based operating system. It provides a
program development and execution environment for assembler, BASIC, and
FORTRAN programs. OS/8 is provided under license, as is, without fee, by
Digital Equipment Corporation, for non-commercial use only. Please read
the enclosed license agreement for full terms and conditions. This license
agreement must be reproduced with any copy of the OS/8 disk images. My
thanks to Doug Jones of the University of Iowa, who provided the disk
images, and to Digital Equipment Corporation, which provided the license.
To boot and run OS/8:
sim> att rx0 os8sys_rx.dsk
sim> att rx1 os8f4_rx.dsk
sim> boot rx0
.DA dd-mmm-yy
.
Note that OS/8 only recognizes upper case characters. The first disk
(drive 0) is the system disk; it also includes BASIC. The second disk
(drive 1) includes FORTRAN.
2. PDP-11
2.1 UNIX V5, V6, V7
UNIX was first developed on the PDP-7; its first widespread usage was on
the PDP-11. UNIX provides a program development and execution environment
for assembler and C programs. UNIX V5, V7, V7 for the PDP-11 is provided
under license, as is, without fee, by Santa Cruz Organization (SCO), for
non-commercial use only. Please read the enclosed license agreement for
full terms and conditions. This license must be reproduced with any copy
of the UNIX V5, V6, V7 disk images. My thanks to PUPS, the PDP-11 UNIX
Preservation Society of Australia, which provided the disk images, and to
SCO, which provided the license.
2.1.1 UNIX V5
UNIX V5 is contained on a single RK05 disk image. To boot UNIX:
sim> set cpu 18b
sim> att rk0 unix_v5_rk.dsk
sim> boot rk
@unix
login: root
#ls -l
2.1.2 UNIX V6
UNIX V6 is contained on three RK05 disk images. To boot UNIX:
sim> set cpu 18b
sim> att rk0 unix0_v6_rk.dsk
sim> att rk1 unix1_v6_rk.dsk
sim> att rk3 unix3_v6_rk.dsk
sim> boot rk0
@unix
login: root
# ls -l
2.1.3 UNIX V7
NOTE: The V7 disk images with V2.3c and later releases are new and
replace the prior versions, which were corrupt.
UNIX V7 is contained on a single RL02 disk image. To boot UNIX:
sim> set cpu 18b
sim> set rl0 RL02
sim> att rl0 unix_v7_rl.dsk
sim> boot rl0
@boot
New Boot, known devices are hp ht rk rl rp tm vt
: rl(0,0)rl2unix
#
A smaller image is contained on a single RK05 disk image. To boot UNIX:
sim> set cpu 18b
sim> att rk0 unix_v7_rk.dsk
sim> boot rk0
@boot
New Boot, known devices are hp ht rk rl rp tm vt
: rk(0,0)rkunix
# STTY -LCASE
#
2.2 RT-11
RT-11 is the PDP-11's single user operating system. It provides a program
development and execution environment for assembler, BASIC, and FORTRAN
programs. RT-11 is provided under license, as is, without fee, by Mentec
Corporation, for non-commercial use ONLY ON THIS SIMULATOR. Please read
the enclosed license agreement for full terms and conditions. This license
agreement must be reproduced with any copy of the RT-11 disk image. My
thanks to John Wilson, a private collector, who provided the disk image
for RT-11 V4; to Megan Gentry, of Digital Equipment Corporation, who
provided the disk image for RT-11 V5.3; and to Mentec Corporation, which
provided the license.
2.2.1 RT-11 V4
RT-11 is contained in a single RK05 disk image. To boot and run RT-11:
sim> att rk0 rtv4_rk.dsk
sim> boot rk0
For RL, RM, and RP series disks, RT-11 expects to find a manufacturer's bad
block table in the last track of the disk. Therefore, INITialization of a
new (all zero's) disk fails, because there is no valid bad block table. To
create a minimal bad block table, use the SET <unit> BADBLOCK command.
2.2.2 RT-11 V5.3
RT-11 is contained in a single RL02 disk image. To boot and run RT-11:
sim> set rl0 rl02
sim> att rl0 rtv53_rl.dsk
sim> boot rl0
This is a full RT-11 distribution kit. It expects the user to copy the
distribution pack and generate a new system. This requires mounting
blank packs on RL1. When a blank pack is attached to the simulator,
a bad block table must be created with the SET <unit> BADBLOCK command.
3. Nova RDOS
RDOS is the Nova's real-time mass storage operating system. It provides a
program development and execution environment for assembler, BASIC, and
FORTRAN programs. RDOS is provided under license, as is, without fee, by
Data General Corporation, for non-commercial use only. Please read the
enclosed license agreement for full terms and conditions. This license
agreement must be reproduced with any copy of the RDOS disk image. My
thanks to Carl Friend, a private collector, who provided the disk image,
and to Data General Corporation, which provided the license.
To boot and run RDOS:
sim> att dp0 rdos_d31.dsk
sim> set tti dasher
sim> boot dp0
FILENAME? (cr)
DATE (mm/dd/yy)? xx/yy/zz
TIME (hh:mm:ss)? hh:mm:ss
R
list/e
4. PDP-1 LISP
PDP-1 LISP is an interactive interpreter for the Lisp language. It can
execute both interactive commands and stored programs. The startup
instructions for LISP are complicated; see the documentation included
with the program for details. My thanks to Peter Deutsch, who wrote the
program, to Gordon Greene, who typed it in from a printed listing, and
to Paul McJones, who helped with the final debug process.
5. PDP-7 SIM8
PDP-7 SIM8 is a PDP-8 simulator for the PDP-7. It implements an 8K
PDP-8/I with keyboard, teleprinter, reader, punch, and line printer.
It provides an interactive console environment for control and debug
of the simulated PDP-8. For more information see the documentation
included with the program. My thanks to Dave Waks, who wrote the
program, and to Paul Pierce and Tim Litt, who recovered the source
from its archival medium.
To load and run SIM8:
sim> load sim8.rim
sim> run
AC/ 0000
6. 1401 Single Card "Koans"
One of the art forms for the IBM 1401 was packing useful programs into a
single punched card. Three samples are included:
i1401_ctolp.cd prints a card deck on the line printer
i1401_ctopu.cd copies a card deck to the card punch
i1401_hello.cd prints "HELLO WORLD" on the line printer and stops
To use the reproduction cards, simply insert them at the beginning of a
text file, terminated by newline. Attach the modified file to the card
reader, attach a blank file to the output device, and boot the card reader.
7. HP2116 16K BASIC
HP BASIC is a paper-tape centric implementation of BASIC for a 16KW
HP2116. Device numbers correspond to the default simulator settings:
PTR = 10
TTY = 11
PTP = 12
The program is a complete but early BASIC and has one unsual requirement:
all programs must include a valid END statement to run correctly. My
thanks to Jeff Moffatt for providing the program.
To load and run BASIC:
sim> load basic1.abs
sim> run 100
READY
10 PRINT SQR(2)
20 END
RUN
1.41421
Appendix 3: Debug Status
The debug status of each simulated CPU and device is as follows:
system PDP-8 PDP-11 Nova PDP-1 18b PDP
device
CPU y y y y y
FPU - y - - -
CIS - h - - -
console y y y y y
paper tape y y y h y
card reader - - - - -
line printer y y y h y
clock y y y - h
hard disk y y y - h
fixed disk h - h - h
floppy disk y y y - -
mag tape h y y - h
system 1401 2100 Id4
device
CPU h y h
FPU - - h
CIS - - -
console h y h
paper tape - h h
card reader h h -
line printer h - -
clock - h -
hard disk - h -
fixed disk - h -
floppy disk - - -
mag tape h h -
legend: y = runs operating system or sample program
d = runs diagnostics
h = runs hand-generated test cases
n = untested
- = not applicable
Revision History (since Rev 1.1)
Rev 2.5, Jan, 01
Removed Digital and Compaq from copyrights, as
authorized by Compaq Sr VP Bill Strecker
Revised save/restore format for 64b simulators
Added examine to file
Added unsigned integer data types to sim_defs
Added Nova 3 and Nova 4 instructions to Nova CPU
Added HP2100
Added Interdata 4
Fixed indirect loop through autoinc/dec in Nova CPU
Fixed MDV enabled test in Nova CPU
Rev 2.4, Jan, 99
Placed all sources under X11-like open source license
Added DUMP command, revised sim_load interface
Added SHOW MODIFIERS command
Revised magtape format to include record error flag
Fixed 64b problems in SCP
Fixed big endian problem in PDP-11 bad block routine
Fixed interrupt on error bug in PDP-11 RP/RM disks
Fixed ROL/ROR inversion in PDP-11 symbolic routines
Rev 2.3d, Sep, 98
Added BeOS support
Added radix commands and switches
Added PDP-11 CIS support
Added RT11 V5.3 to distribution kits
Fixed "shift 32" bugs in SCP, PDP-11 floating point
Fixed bug in PDP-11 paper tape reader
Fixed bug in ^D handling
Rev 2.3c, May, 98
Fixed bug in PDP-11 DIV overflow check
Fixed bugs in PDP-11 magtape bootstrap
Fixed bug in PDP-11 magtape unit select
Replaced UNIX V7 disk images
Rev 2.3b, May, 98
Added switch recognition to all simulator commands
Added RIM loader to PDP-8 paper tape reader and loader
Added second block bootstrap to PDP-11 magtape
Fixed bug in PDP-8 RF bootstrap
Fixed bug in PDP-11 symbolic display
Fixed bugs in PDP-11 floating point (LDEXP, STEXP,
MODf, STCfi, overflow handling)
Rev 2.3a, Nov, 97
Added search capability
Added bad block table command to PDP-11 disks
Added bootstrap to PDP-11 magtape
Added additional Nova moving head disks
Added RT-11 sample software
Fixed bugs in PDP-11 RM/RP disks
Fixed bugs in Nova moving head disks
Fixed endian dependence in 18b PDP RIM loader
Rev 2.3, Mar, 97
Changed UNIX terminal I/O to TERMIOS
Changed magtape format to double ended
Changed PDP-8 current page mnemonic from T to C
Added endian independent I/O routines
Added precise integer data types
Fixed bug in sim_poll_kbd
Fixed bug in PDP-8 binary loader
Fixed bugs in TM11 magtape
Fixed bug in RX11 bootstrap
Fixed bug in 18b PDP ADD
Fixed bug in 18b PDP paper tape reader
Fixed bug in PDP-4 console
Fixed bug in PDP-4,7 line printer
Added PDP-11 RP
Added PDP-1
Rev 2.2d, Dec, 96
Added ADD/REMOVE commands
Added unit enable/disable support to device simulators
Added features for IBM 1401 project
Added switch recognition for symbolic input
Fixed bug in variable length IEXAMINE
Fixed LCD bug in RX8E
Initial changes for Win32
Added IBM 1401
Rev 2.2b, Apr, 96
Added PDP-11 dynamic memory size support
Rev 2.2a, Feb, 96
New endian independent magtape format
Rev 2.2 Jan, 96
Added register buffers for save/restore
Added 18b PDP's
Guaranteed TTI, CLK times are non-zero
Fixed breakpoint/RUN interaction bug
Fixed magnetic tape backspace to EOF bug
Fixed ISZ/DCA inversion in PDP-8 symbol table
Fixed sixbit conversion in PDP-8 examine/deposit
Fixed origin increment bug in PDP-11 binary loader
Fixed GCC longjmp optimization bug in PDP-11 CPU
Fixed unit number calculation bug in SCP and in
Nova, PDP-11, 18b PDP moving head disks
Rev 2.1 Dec, 95
Fixed PTR bug (setting done on EOF) in PDP-8, Nova
Fixed RX bug (setting error on INIT if drive 1 is
not attached) in PDP-8, PDP-11
Fixed RF treatment of photocell flag in PDP-8
Fixed autosize bug (always chose smallest disk if new
file) in PDP-11, Nova
Fixed not attached bug (reported as not attachable) in
most mass storage devices
Fixed Nova boot ROMs
Fixed bug in RESTORE (didn't requeue if delay = 0)
Fixed bug in RESTORE (clobbered device position)
Declared static constant arrays as static const
Added PDP-8, Nova magnetic tape simulators
Added Dasher mode to Nova terminal simulator
Added LINUX support
Rev 2.0 May, 95
Added symbolic assembly/disassembly
Acknowledgements
SIMH would not have been possible without help from around the world. I
would like to acknowledge the help of the following people, all of whom
donated their time and talent to this "computer archaeology" project:
Bill Ackerman PDP-1 consulting
Winfried Bergmann Linux port testing
Phil Budne Solaris port testing
Max Burnet PDP information, documentation, and software
James Carpenter LINUX port testing
Chip Charlot PDP-11 RT-11, RSTS/E, RSX-11M legal permissions
Dave Conroy HP 21xx documentation
L Peter Deutsch PDP-1 LISP software
Ethan Dicks PDP-11 2.9 BSD debugging
Carl Friend Nova and Interdata documentation, and RDOS software
Megan Gentry PDP-11 integer debugging, make file
Dick Greeley PDP-8 OS/8 and PDP-10 TOPS-10/20 legal permissions
Gordon Greene PDP-1 LISP machine readable source
Lynne Grettum PDP-11 RT-11, RSTS/E, RSX-11M legal permissions
Franc Grootjen PDP-11 2.11 BSD debugging
Ken Harrenstein PDP-10 simulator
Bill Haygood PDP-8 information, simulator, and software
Jim Jaeger IBM 1401 information
Doug Jones PDP-8 information, simulator, and software
Don Lewine Nova documentation and legal permissions
Scott McGregor PDP-11 UNIX legal permissions
Jeff Moffatt HP 2100 information, documentation, and software
Alec Muffett Solaris port testing
Dutch Owen Nova moving head disk debugging, Altair simulator
Paul Pierce IBM 1401 diagnostics, media recovery
Craig St Clair PDP documentation
Richard Schedler Public repository maintenance
Stephen Schultz PDP-11 2.11 BSD debugging
Olaf Seibert NetBSD port testing
Brian & Barry Silverman PDP-1 simulator and software
Tim Shoppa Nova documentation and RDOS software
Michael Somos PDP-1 debugging
Hans-Michael Stahl OS/2 port testing, TERMIOS implementation
Larry Stewart Initial suggestion for the project
Bill Strecker Permission to revert copyrights
Chris Suddick PDP-11 floating point debugging
Ben Thomas VMS character-by-character I/O routines
Warren Toomey PDP-11 UNIX software
Deb Toivonen PDP documentation
Leendert Van Doorn PDP-11 UNIX V6 debugging, TERMIOS implementation
David Waks PDP-8 ESI-X and PDP-7 SIM8 software
Tom West Nova documentation
John Wilson PDP-11 simulator and software
In addition, the following companies have graciously licensed their
software at no cost for hobbyist use:
Data General Corporation
Digital Equipment Corporation
Compaq Computer Corporation
Mentec Corporation
The Santa Cruz Operation