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Altair 8800 Simulator with Z80 support
======================================
0. Revision History
Original version of this document written by Charles E Owen
- 9-Oct-2002, Peter Schorn (added support for simulated hard disk)
- 28-Sep-2002, Peter Schorn (number of tracks per disk can be configured)
- 19-Sep-2002, Peter Schorn (added WARNROM feature)
- 31-Aug-2002, Peter Schorn (added extended ROM features suggested by Scott LaBombard)
- 4-May-2002, Peter Schorn (added description of MP/M II sample software)
- 28-Apr-2002, Peter Schorn (added periodic timer interrupts and three
additional consoles)
- 15-Apr-2002, Peter Schorn (added memory breakpoint)
- 7-Apr-2002, Peter Schorn (added ROM / NOROM switch)
1. Background.
The MITS (Micro Instrumentation and Telemetry Systems) Altair 8800
was announced on the January 1975 cover of Popular Electronics, which
boasted you could buy and build this powerful computer kit for only $397.
The kit consisted at that time of only the parts to build a case, power
supply, card cage (18 slots), CPU card, and memory card with 256 *bytes* of
memory. Still, thousands were ordered within the first few months after the
announcement, starting the personal computer revolution as we know it today.
Many laugh at the small size of the that first kit, noting there
were no peripherals and the 256 byte memory size. But the computer was an
open system, and by 1977 MITS and many other small startups had added many
expansion cards to make the Altair quite a respectable little computer. The
"Altair Bus" that made this possible was soon called the S-100 Bus, later
adopted as an industry standard, and eventually became the IEE-696 Bus.
2. Hardware
We are simulating a fairly "loaded" Altair 8800 from about 1977,
with the following configuration:
device simulates
name(s)
CPU Altair 8800 with Intel 8080 CPU board, 62KB
of RAM, 2K of EPROM with start boot ROM.
SIO MITS 88-2SIO Dual Serial Interface Board. Port 1
is assumed to be connected to a serial "glass
TTY" that is your terminal running the Simulator.
PTR Paper Tape Reader attached to port 2 of the 2SIO board.
PTP Paper Tape Punch attached to port 2 of the
2SIO board. This also doubles as a printer port.
DSK MITS 88-DISK Floppy Disk controller with up
to eight drives.
2.1 CPU
We have 2 CPU options that were not present on the original
machine but are useful in the simulator. We also allow you to select
memory sizes, but be aware that some sample software requires the full
64K (i.e. CP/M) and the MITS Disk Basic and Altair DOS require about
a minimum of 24K.
SET CPU 8080 Simulates the 8080 CPU (normal)
SET CPU Z80 Simulates the Z80 CPU. Note that some software (e.g. most
original Altair software such as 4K Basic) requires an 8080 CPU and
will not or not properly run on a Z80. This is mainly due to the use
of the parity flag on the 8080 which has not always the same
semantics on the Z80.
SET CPU ITRAP Causes the simulator to halt if an invalid opcode
is detected (depending on the chosen CPU).
SET CPU NOITRAP Does not stop on an invalid Opcode. This is
how the real 8080 works.
SET CPU 4K
SET CPU 8K
SET CPU 12K
SET CPU 16K
......
SET CPU 64K All these set various CPU memory configurations.
The 2K EPROM at the high end of memory is always
present and will always boot.
SET CPU BANKED Enables the banked memory support. The simulated memory
has eight banks with address range 0..'common' (see registers below)
and a common area from 'common' to 0xfff which is common to all
banks. The currently active bank is determined by register 'bank'
(see below). You can only switch to banked memory if the memory
is set to 64K. The banked memory is used by CP/M 3.
SET CPU NONBANKED Disables banked memory support.
SET CPU ROM Enables the ROM from address 'ROMLOW' to 'ROMHIGH'
(see below under CPU Registers) and prevents write access
to these locations. This is the default setting.
SET CPU NOROM Disables the ROM.
SET CPU ALTAIRROM Enables the slightly modified but downwards compatible
Altair boot ROM at addresses 0FF00 to 0FFFF. This is the default.
SET CPU NOALTAIRROM Disables standard Altair ROM behavior.
SET CPU WARNROM Enables warning messages to be printed when the CPU
attempts to write into ROM or into non-existing memory. Also prints
a warning message if the CPU attempts to read from non-existing
memory.
SET CPU NOWARNROM Suppreses all warning message of "WARNROM". Note that
some software tries on purpose to write to ROM in order to detect
the available RAM.
The BOOT EPROM card starts at address 0FF00 if it has been enabled by 'SET
CPU ALTAIRROM'. Jumping to this address will boot drive 0 of the floppy
controller (CPU must be set to ROM or equivalent code must be present). If
no valid bootable software is present there the machine crashes. This is
historically accurate behavior.
The real 8080, on receiving a HLT (Halt) instruction, freezes the processor
and only an interrupt or CPU hardware reset will restore it. The simulator
is alot nicer, it will halt but send you back to the simulator command line.
CPU Registers include the following:
Name Size Comment
PC 16 The Program Counter
AF 16 The accumulator and the flag register
F = S Z - AC - P/V N C
S = Sign flag.
Z = Zero Flag.
AC = Auxillary Carry flag.
P/V = Parity flag on 8080
Parity / Overflow flag on Z80
- = not used (undefined)
N = Internal sign flag
C = Carry flag.
BC 16 The BC register pair. Register B is the high 8 bits,
C is the lower 8 bits
DE 16 The DE register pair. Register D is the high 8 bits,
E is the lower 8 bits.
HL 16 The HL register pair. Register H is the high 8 bits,
L is the lower 8 bits.
AF1 16 The alternate AF register (only on Z80)
BC1 16 The alternate BC register (only on Z80)
DE1 16 The alternate DE register (only on Z80)
HL1 16 The alternate HL register (only on Z80)
IX 16 The IX index register (only on Z80)
IY 16 The IY index register (only on Z80)
IFF 8 Interrupt flag (only on Z80, no effect)
INT 8 Interrupt register (only on Z80, no effect)
SR 16 The front panel switches (use D SR 8 for 4k Basic).
WRU 8 The interrupt character. This starts as 5
(ctrl-E) but some Altair software uses this
keystroke so best to change this to something
exotic such as 035 (which is Ctl-]).
BANK 3 The currently active memory bank (if banked memory
is activated - see memory options above)
COMMON 16 The starting address of common memory. Originally set
to 0xc000 (note this setting must agree with the
value supplied to GENCPM for CP/M 3 system generation)
ROMLOW 16 The starting address of the ROM. Default is 0FF00.
ROMHIGH 16 The final address of the ROM. Default is 0FFFF.
2.2 The Serial I/O Card (2SIO)
This simple programmed I/O device provides 2 serial ports to the
outside world, which could be hardware jumpered to support RS-232 plugs or a
TTY current loop interface. The standard I/O addresses assigned by MITS
was 10-11 (hex) for the first port, and 12-13 (hex) for the second.
We follow this standard in the Simulator.
The simulator directs I/O to/from the first port to the screen. The
second port reads from an attachable "tape reader" file on input, and writes
to an attachable "punch file" on output. These files are considered a
simple stream of 8-bit bytes.
The SIO can be configured in SIMH with the following commands:
SET SIO TTY Bit 8 is set to zero on console output
SET SIO ANSI Bit 8 is not touched on console output
SET SIO ALL Console input support lower- and upper case
SET SIO UPPER Console input is transformed to upper case characters only
(This feature is useful for most Altair software)
SET SIO BS Map the delete character to backspace
SET SIO DEL Map the backspace character to delete
SET SIO QUIET Do not print warning messages
SET SIO VERBOSE Print warning messages (useful for debugging)
The register SIOWL determines how often the same warning
is displayed. The default is 3.
You can also attach the SIO to a port:
ATTACH SIO 23 Console IO goes via a Telnet connection on port 23
DETACH SIO Console IO goes via the regular SIMH console
2.3 The SIMH pseudo device
The SIMH pseudo device facilitates the communication between the simulated
ALTAIR and the simulator environment. This device defines a number of (most R/O)
registers (see source code) which are primarily useful for debugging purposes.
The SIMH pseudo device can be configured with
SET SIMH QUIET Do not print warning messages
SET SIMH VERBOSE Print warning messages (useful for debugging)
SET SIMH TIMERON Start periodic timer interrupts
SET SIMH TIMEROFF Stop the periodic timer interrupts
The following variables determine the behavior of the timer:
TIMD This is the delay between consecutive interrupts in milliseconds.
Use D TIMD 20 for a 50 Hz clock.
TIMH This is the address of the interrupt handler to call for a
timer interrupt.
2.4 The 88-DISK controller.
The MITS 88-DISK is a simple programmed I/O interface to the MITS
8-inch floppy drive, which was basically a Pertec FD-400 with a power
supply and buffer board builtin. The controller supports neither interrupts
nor DMA, so floppy access required the sustained attention of the CPU.
The standard I/O addresses were 8, 9, and 0A (hex), and we follow the
standard. Details on controlling this hardware are in the altair_dsk.c
source file.
The only difference is that the simulated disks may be larger than the
original ones: The original disk had 77 tracks while the simulated disks
support up to 254 tracks (only relevant for CP/M). You can change the
number of tracks per disk by setting the appropriate value in TRACKS[..].
For example "D TRACKS[0] 77" sets the number of tracks for disk 0 to
the original number of 77. The command "D TRACKS[0-7] 77" changes the
highest track number for all disks to 77.
For debugging purposes you can set the trace level of some disk I/O
functions. To do so the following bits in TRACE (a register of the disk)
have been defined with the following meaning:
1 Trace all IN and OUT instructions on the disk ports 8 and 9
2 Trace all read and writes to full sectors on the disk
4 Print a message whenever an unnecessary step-in or step out of the
disk head occurs (often an indication of an infinite loop)
8 Print a message whenever the disk head appears to be waiting for a
sector which does not show up (often an indication of an infinite
loop)
For example the command "D TRACE 10" will trace options 2+8 from above.
The DSK device can be configured with
SET DSK<n> QUIET Do not print warning messages for disk <n>
SET DSK<n> VERBOSE Print warning messages for disk <n>
(useful for debugging)
The register DSKWL determines how often the
same warning is displayed. The default is 3.
SET DSK<n> WRITEENABLED Allow write operations for disk <n>
SET DSK<n> LOCKED Disk <n> is locked, i.e. no write operations
will be allowed.
2.5 The simulated hard disk
In order to increase the available storage capacity, the simulator
features 8 simulated hard disks with a capacity of 8MB (HDSK0 to HDSK7).
Currently only CP/M supports two hard disks as devices I: and J:.
For debugging purposes one can set the trace flag by executing the
command "D HDTRACE 1". The default for "HDTRACE" is 0 (no trace).
The HDSK device can be configured with
SET HDSK<n> QUIET Do not print warning messages for hard disk <n>
SET HDSK<n> VERBOSE Print warning messages for hard disk <n>
(useful for debugging)
SET HDSK<n> WRITEENABLED Allow write operations for hard disk <n>
SET HDSK<n> LOCKED Hard disk <n> is locked, i.e. no
write operations will be allowed.
3. Sample Software
Running an Altair in 1977 you would be running either MITS Disk
Extended BASIC, or the brand new and sexy CP/M Operating System from Digital
Research. Or possibly, you ordered Altair DOS back when it was promised in
1975, and are still waiting for it to be delivered in early 1977.
We have samples of all three for you to check out. We can't go into
the details of how they work, but we'll give you a few hints.
3.1 CP/M Version 2.2
This version is my own port of the standard CP/M to the Altair.
There were some "official" versions but I don't have them. None were
endorsed or sold by MITS to my knowledge, however.
To boot CP/M:
sim> attach dsk cpm2.dsk
sim> boot dsk
CP/M feels like DOS, sort of. DIR will work. I have included all
the standard CP/M utilities, plus a few common public-domain ones. I also
include the sources to the customized BIOS and some other small programs.
TYPE will print an ASCII file. DUMP will dump a binary one. LS is a better
DIR than DIR. ASM will assemble .ASM files to Hex, LOAD will "load" them to
binary format (.COM). ED is a simple editor, #A command will bring the
source file to the buffer, T command will "type" lines, L will move lines,
E exits the editor. 20L20T will move down 20 lines, and type 20. Very
DECish. DDT is the debugger, DO is a batch-type command processor.
A sample batch file that will assemble and write out the bootable CP/M
image (on drive A) is "SYSCPM2.SUB". To run it, type "DO SYSCPM2".
In order to efficiently transfer files into the CP/M environment use the
included program R <filename.ext>. If you have a file named foo.ext in
the current directory (i.e. the directory where SIMH is), executing
R FOO.EXT under CP/M will transfer the file onto the CP/M disk.
Transferring a file from the CP/M environment to the SIMH environment is
accomplished by W <filename.ext>.
If you need more storage space you can use a simulated hard disk on
drives I: and J:. To use do "attach HDSK0 hdi.dsk" and issue the
"XFORMAT I:" resp. "XFORMAT J:" command from CP/M do initialize the disk
to an empty state.
The disk "cpm2.dsk" contains the following files:
Name Ext Size Comment
ASM .COM 8K ; CP/M assembler
BDOS .MAC 68K ; Basic Disk Operating System assembler source code
BOOT .COM 1K ; transfer control to boot ROM
BOOT .MAC 2K ; source for BOOT.COM
BOOTGEN .COM 2K ; put a program on the boot sectors
CBIOSX .MAC 48K ; CP/M 2 BIOS source for Altair
CCP .MAC 26K ; Console Command Processor assembler source code
COPY .COM 2K ; copy disks
CPMBOOT .COM 12K ; CP/M operating system
CREF80 .COM 4K ; cross reference utility
DDT .COM 6K ; 8080 debugger
DDTZ .COM 10K ; Z80 debugger
DIF .COM 4K ; determine differences between two files
DO .COM 2K ; batch processing
DSKBOOT .MAC 8K ; source for boot ROM
DUMP .COM 2K ; hex dump a file
ED .COM 8K ; line editor
ELIZA .BAS 10K ; Elisa game in Basic
EX8080 .COM 10K ; exercise 8080 instruction set
EX8080 .MAC 48K ; source for EX8080.COM
EX8080 .SUB 2K ; benchmark execution of EX8080.COM
EXZ80 .COM 10K ; exercise Z80 instruction set
EXZ80 .MAC 48K ; source for EXZ80.COM
EXZ80 .SUB 2K ; benchmark execution of EXZ80.COM
FORMAT .COM 2K ; format disks
GO .COM 0K ; start the currently loaded program at 100H
HDSKBOOT.MAC 6K ; boot code for hard disk
L80 .COM 12K ; Microsoft linker
LADDER .COM 40K ; game
LADDER .DAT 2K ; high score file for LADDER.COM
LIB80 .COM 6K ; library utility
LOAD .COM 2K ; load hex files
LS .COM 4K ; directory utility
LU .COM 20K ; library utility
M80 .COM 20K ; Microsoft macro assembler
MBASIC .COM 24K ; Microsoft Basic interpreter
MC .SUB 2K ; assemble and link an assembler program
MCC .SUB 2K ; read, assemble and link an assembler program
MCCL .SUB 2K ; assemble, link and produce listing
MEMCFG .LIB 2K ; defines the memory configuration
MOVER .MAC 2K ; moves operating system in place
OTHELLO .COM 12K ; Othello (Reversi) game
PIP .COM 8K ; Peripheral Interchange Program
R .COM 4K ; read files from SIMH environment
RSETSIMH.COM 2K ; reset SIMH interface
RSETSIMH.MAC 2K ; assembler source for RSETSIMH.COM
SHOWSEC .COM 3K ; show sectors on a disk
SID .COM 8K ; debugger for 8080
STAT .COM 6K ; provide information about currently logged disks
SURVEY .COM 2K ; system survey
SURVEY .MAC 16K ; assembler source for SURVEY.COM
SYSCOPY .COM 2K ; copy system tracks between disks
SYSCPM2 .SUB 2K ; create CP/M 2 on drive A:
TIMER .COM 2K ; perform various timer operations
TIMER .MAC 2K ; source code for TIMER.COM
UNCR .COM 8K ; un-crunch utility
UNERA .COM 2K ; un-erase a file
UNERA .MAC 16K ; source for UNERA.COM
USQ .COM 2K ; un-squeeze utility
W .COM 4K ; write files to SIMH environment
WM .COM 12K ; word master screen editor
WM .HLP 3K ; help file for WM.COM
WORM .COM 4K ; worm game for VT100 terminal
XFORMAT .COM 2K ; initialise a drive (floppy or hard disk)
XSUB .COM 2K ; support for DO.COM
ZSID .COM 10K ; debugger for Z80
ZTRAN4 .COM 4K ; translate 8080 mnemonics into Z80 equivalents
3.2 CP/M Version 3 with banked memory
CP/M 3 is the successor to CP/M 2.2. A customised BIOS (BIOS3.MAC)
is included to facilitate modification if so desired. The defaults supplied in
GENCPM.DAT for system generation can be used. BOOTGEN.COM is used to
place the CP/M loader (LDR.COM) on the boot tracks of a disk.
Running CP/M 3 with banked memory:
sim> attach dsk cpm3.dsk
sim> reset cpu
sim> set cpu banked
sim> set cpu itrap
sim> boot dsk
Executing "DO SYSCPM3" will re-generate the banked version of CP/M 3.
You can boot CP/M 3 with or without a Z80 CPU. The Z80 CPU is needed for
both sysgens due to the use of BOOTGEN.COM which requires it.
The disk "cpm3.dsk" contains the following files:
ASM .COM 8K ; CP/M assembler
ASSIGN .SYS 2K
BDOS3 .SPR 10K
BIOS3 .MAC 28K ; CP/M 3 BIOS source for Altair SIMH
BIOS3 .SPR 4K
BNKBDOS3.SPR 14K
BNKBIOS3.SPR 4K
BOOT .COM 2K ; transfer control to boot ROM
BOOTGEN .COM 2K ; put a program on the boot sectors
CCP .COM 4K
COPYSYS .COM 2K
CPM3 .SYS 18K
CPMLDR .MAC 38K ; CP/M 3 loader assembler source
DATE .COM 4K ; date utility
DDT .COM 6K ; 8080 debugger
DDTZ .COM 10K ; Z80 debugger
DEFS .LIB 2K ; include file for BIOS3.MAC to create banked CP/M 3
DEVICE .COM 8K
DIF .COM 4K ; determine differences between two files
DIR .COM 16K ; directory utility
DO .COM 6K ; batch processing
DUMP .COM 2K
ED .COM 10K
ERASE .COM 4K
GENCOM .COM 16K
GENCPM .COM 22K
GENCPM .DAT 4K ; CP/M generation information for banked version
GENCPMNB.DAT 4K ; CP/M generation information for non-banked version
GET .COM 8K
HELP .COM 8K ; help utility
HELP .HLP 62K ; help files
HEXCOM .CPM 2K
HIST .UTL 2K
INITDIR .COM 32K
L80 .COM 12K ; Microsoft linker
LDR .COM 4K ; CP/M loader with optimised loader BIOS
LDRBIOS3.MAC 14K ; optimised (for space) loader BIOS
LIB .COM 8K ; Digital Research librarian
LINK .COM 16K ; Digital Research linker
LOAD .COM 2K
M80 .COM 20K ; Microsoft macro assembler
MC .SUB 2K ; assemble and link an assmbler program
MCC .SUB 2K ; read, assemble and link an assembler program
PATCH .COM 4K
PIP .COM 10K ; Peripheral Interchange Program
PROFILE .SUB 2K ; commands to be executed at start up
PUT .COM 8K
R .COM 4K ; read files from SIMH environment
RENAME .COM 4K
RESBDOS3.SPR 2K
RMAC .COM 14K ; Digital Research macro assembler
RSETSIMH.COM 2K ; reset SIMH interface
SAVE .COM 2K
SCB .MAC 2K
SET .COM 12K
SETDEF .COM 6K
SHOW .COM 10K
SHOWSEC .COM 4K ; show sectors on a disk
SID .COM 8K ; 8080 debugger
SYSCOPY .COM 2K ; copy system tracks between disks
SYSCPM3 .SUB 2K ; create banked CP/M 3 system
TRACE .UTL 2K
TSHOW .COM 2K ; show split time
TSTART .COM 2K ; create timer and start it
TSTOP .COM 2K ; show final time and stop timer
TYPE .COM 4K
UNERA .COM 2K ; un-erase a file
W .COM 4K ; write files to SIMH environment
XREF .COM 16K ; cross reference utility
ZSID .COM 10K ; Z80 debugger
3.3 MP/M II with banked memory
MP/M II is an acronym for MultiProgramming Monitor Control Program for
Microprocessors. It is a multiuser operating system for an eight bit
microcomputer. MP/M II supports multiprogramming at each terminal. This
version supports four terminals available via Telnet. To boot:
sim> attach dsk mpm.dsk
sim> set cpu itrap
sim> set cpu z80
sim> set cpu rom
sim> set cpu banked
sim> attach sio 23
sim> d common b000
sim> boot dsk
Now connect a Telnet session to the simulator and type "MPM" at the "A>"
prompt. Now you can connect up to three additional terminals via Telnet
to the Altair running MP/M II. To re-generate the system perform
"DO SYSMPM" in the CP/M environment (not possible under MP/M since XSUB
is needed).
The disk "mpm.dsk" contains the following files:
Name Ext Size Comment
ABORT .PRL 2K ; abort a process
ABORT .RSP 2K
ASM .PRL 10K ; MP/M assembler
BNKBDOS .SPR 12K ; banked BDOS
BNKXDOS .SPR 2K ; banked XDOS
BNKXIOS .SPR 4K ; banked XIOS
BOOTGEN .COM 2K ; copy an executable to the boot section
CONSOLE .PRL 2K ; print console number
CPM .COM 2K ; return to CP/M
CPM .MAC 2K ; source for CPM.COM
DDT .COM 6K ; MP/M DDT
DDT2 .COM 6K ; CP/M DDT
DDTZ .COM 10K ; CP/M DDT with Z80 support
DIF .COM 4K ; difference between two files
DIR .PRL 2K ; directory command
DO .COM 2K ; CP/M submit
DSKRESET.PRL 2K ; disk reset command
DUMP .MAC 6K ; source for DUMP.PRL
DUMP .PRL 2K ; dump command
ED .PRL 10K ; MP/M line editor
ERA .PRL 2K ; erase command
ERAQ .PRL 4K ; erase comand (verbose)
GENHEX .COM 2K
GENMOD .COM 2K
GENSYS .COM 10K
L80 .COM 12K ; Microsoft linker
LDRBIOS .MAC 14K ; loader BIOS
LIB .COM 8K ; library utility
LINK .COM 16K ; linker
LOAD .COM 2K ; loader
M80 .COM 20K ; Microsoft macro assembler
MC .SUB 2K ; assemble and link an assmbler program
MCC .SUB 2K ; read, assemble and link an assembler program
MPM .COM 8K ; start MP/M II
MPM .SYS 26K ; MP/M system file
MPMD .LIB 2K ; define a banked system
MPMLDR .COM 6K ; MP/M loader without LDRBIOS
MPMSTAT .BRS 6K ; status of MP/M system
MPMSTAT .PRL 6K
MPMSTAT .RSP 2K
MPMXIOS .MAC 26K ; XIOS for MP/M
PIP .PRL 10K ; MP/M peripheral interchange program
PIP2 .COM 8K ; CP/M peripheral interchange program
PRINTER .PRL 2K
PRLCOM .PRL 4K
R .COM 4K ; read a file from the SIMH environment
RDT .PRL 8K ; debugger for page relocatable programs
REN .PRL 4K ; rename a file
RESBDOS .SPR 4K ; non-banked BDOS
RMAC .COM 14K ; Digital Research macro assembler
RSETSIMH.COM 2K ; reset SIMH interface
SCHED .BRS 2K ; schedule a job
SCHED .PRL 4K
SCHED .RSP 2K
SDIR .PRL 18K ; fancy directory command
SET .PRL 8K ; set parameters
SHOW .PRL 8K ; show status of disks
SPOOL .BRS 4K ; spool utility
SPOOL .PRL 4K
SPOOL .RSP 2K
STAT .COM 6K ; CP/M stat command
STAT .PRL 10K ; MP/M stat command
STOPSPLR.PRL 2K ; stop spooler
SUBMIT .PRL 6K ; MP/M submit
SYSCOPY .COM 2K ; copy system tracks
SYSMPM .SUB 2K ; do a system generation
SYSTEM .DAT 2K ; default values for system generation
TMP .SPR 2K
TOD .PRL 4K ; time of day
TSHOW .COM 2K ; show split time
TSTART .COM 2K ; create timer and start it
TSTOP .COM 2K ; show final time and stop timer
TYPE .PRL 2K ; type a file on the screen
USER .PRL 2K ; set user area
W .COM 4K ; write a file to SIMH environment
XDOS .SPR 10K ; XDOS
XREF .COM 16K ; cross reference utility
XSUB .COM 2K ; for CP/M DO
3.5 CP/M application software
There is also a small collection of sample application software containing
the following items:
- SPL: a Small Programming Language with a suite of sample programs
- PROLOGZ: a Prolog interpreter written in SPL with sources
- PASCFORM: a Pascal pretty printer written in Pascal
- Pascal MT+: Pascal language system needed to compile PASCFORM
The sample software comes on "app.dsk" and to use it do
sim> attach dsk1 app.dsk
before booting CP/M.
The disk "app.dsk" contains the following files:
Name Ext Size Comment
BOOTGEN .COM 2K
BOOTGEN .SPL 6K ; SPL source for BOOTGEN.COM
C .SUB 2K ; batch file for compiling an SPL source file
CALC .PRO 4K ; Prolog demo program calculator
CC .SUB 2K ; compile an SPL source which is on the underlying
file system
DECLARAT. 12K ; common include file, SPL source
DIF .COM 4K
DIF .SPL 10K ; SPL source for DIF.COM
EDIT .SPL 10K ; screen editor for PROLOGZ, SPL source
FAMILY .PRO 4K ; Prolog demo program family relations
INTEGER .PRO 2K ; Prolog demo program integer arithmetic
KNAKE .PRO 2K ; Prolog demo program logic puzzle
LINKMT .COM 12K ; Pascal MT+ 5.5 linker
MAIN .SPL 14K ; main module for PROLOGZ, SPL source
MOVE .MAC 4K ; helper functions for PROLOGZ in assembler
MTERRS .TXT 6K ; Pascal MT+ error messages
MTPLUS .000 14K ; Pascal MT+ 5.5 compiler file
MTPLUS .001 12K ; Pascal MT+ 5.5 compiler file
MTPLUS .002 8K ; Pascal MT+ 5.5 compiler file
MTPLUS .003 8K ; Pascal MT+ 5.5 compiler file
MTPLUS .004 18K ; Pascal MT+ 5.5 compiler file
MTPLUS .005 8K ; Pascal MT+ 5.5 compiler file
MTPLUS .006 6K ; Pascal MT+ 5.5 compiler file
MTPLUS .COM 36K ; Pascal MT+ 5.5 compiler
PASCFORM.COM 36K ; Pascal formatter
PASCFORM.PAS 54K ; Pascal formatter source code
PASCFORM.SUB 2K ; create Pascal formatter
PASLIB .ERL 24K ; Pascal MT+ 5.5 run time library
PINST .COM 4K ; terminal installation program for PROLOGZ
PINST .SPL 16K ; terminal installation program for PROLOGZ,
SPL source
PROLOGZ .COM 18K ; PROLOGZ interpreter and screen editor
PROLOGZ .SPL 2K ; PROLOGZ main program, SPL source
PROLOGZ .TXT 40K ; PROLOGZ documentation in German
PROVE .SPL 16K ; backtrack theorem prover for PROLOGZ, SPL source
PZCLEAN .SUB 2K ; PROLOGZ: remove all created ".rel" and ".lst" files
PZLINK .SUB 2K ; PROLOGZ: create PINST, PROLOGZ and personalise the
serial number
PZMAKE .SUB 2K ; compiles the sources (you can ignore any compiler
errors)
QUEEN .PRO 2K ; Prolog demo program n-queens problem
READ .COM 4K
READ .SPL 10K ; SPL source for R.COM
SHOWSEC .COM 4K
SHOWSEC .SPL 6K ; SPL source for SHOWSEC.COM
SPL .COM 38K ; the SPL compiler itself
SPL .TXT 56K ; SPL language and compiler documentation in German
SPLERROR.DAT 12K ; error messages of the compiler (in German)
SPLIB .REL 6K ; SPL runtime library
STDIO . 2K ; include file for SPL programs
SYSCOPY .COM 2K
SYSCOPY .SPL 6K ; SPL source for SYSCOPY.COM
TERMBDOS.SPL 2K ; terminal interface to CP/M for PROLOGZ, SPL source
UTIL .SPL 18K ; utility functions for PROLOGZ, SPL source
WRITE .COM 4K
WRITE .SPL 8K ; SPL source for W.COM
XFORMAT .COM 2K
XFORMAT .SPL 6K ; SPL source for XFORMAT.COM
3.6 MITS Disk Extended BASIC Version 4.1
This was the commonly used software for serious users of the Altair
computer. It is a powerful (but slow) BASIC with some extended commands to
allow it to access and manage the disk. There was no operating system it
ran under. To boot:
sim> set cpu 8080 ;Z80 will not work
sim> attach dsk mbasic.dsk
sim> set sio upper
sim> go ff00
MEMORY SIZE? [return]
LINEPRINTER? [C return]
HIGHEST DISK NUMBER? [0 return] (0 here = 1 drive system)
NUMBER OF FILES? [3 return]
NUMBER OF RANDOM FILES? [2 return]
44041 BYTES FREE
ALTAIR BASIC REV. 4.1
[DISK EXTENDED VERSION]
COPYRIGHT 1977 BY MITS INC.
OK
[MOUNT 0]
OK
[FILES]
3.7 Altair DOS Version 1.0
This was long promised but not delivered until it was almost
irrelevant. A short attempted tour will reveal it to be a dog, far inferior
to CP/M. To boot:
sim> d tracks[0-7] 77 ;set to Altair settings
sim> set cpu altairrom
sim> attach dsk altdos.dsk
sim> set sio upper
sim> go ff00
MEMORY SIZE? [return]
INTERRUPTS? N [return]
HIGHEST DISK NUMBER? [0 return] (3 here = 4 drive system)
HOW MANY DISK FILES? [3 return]
HOW MANY RANDOM FILES? [2 return]
056449 BYTES AVAILABLE
DOS MONITOR VER 1.0
COPYRIGHT 1977 BY MITS INC
.[MNT 0]
.[DIR 0]
3.8 Altair Basic 3.2 (4k)
In order to run the famous 4k Basic, use the following commands (the trick
is to get the Switch Register right).
sim> set cpu 8080 ;note 4k Basic will not run on a Z80 CPU
sim> set sio upper ;4k Basic does not like lower case letters as input
sim> set sio ansi ;4k Basic produces 8-bit output, strip to seven bits
sim> d sr 8 ;good setting for the Switch Register
sim> load 4kbas.bin 0 ;load it at 0
sim> go 0 ;and start it
MEMORY SIZE? [return]
TERMINAL WIDTH? [return]
WANT SIN? [Y]
61911 BYTES FREE
BASIC VERSION 3.2
[4K VERSION]
OK
3.9 Altair 8k Basic
Running 8k Basic follows the procedure for 4k Basic.
sim> set cpu 8080 ;note 8k Basic will not run on a Z80 CPU
sim> set sio upper ;8k Basic does not like lower case letters as input
sim> set sio ansi ;8k Basic produces 8-bit output, strip to seven bits
sim> d sr 8 ;good setting for the Switch Register
sim> load 8kbas.bin 0 ;load it at 0
sim> go 0 ;and start it
MEMORY SIZE? [A]
WRITTEN FOR ROYALTIES BY MICRO-SOFT
MEMORY SIZE? [return]
TERMINAL WIDTH? [return]
WANT SIN-COS-TAN-ATN? [Y]
58756 BYTES FREE
ALTAIR BASIC REV. 4.0
[EIGHT-K VERSION]
COPYRIGHT 1976 BY MITS INC.
OK
3.10 Altair Basic 4.0
Execute the following commands to run Altair Extended Basic:
sim> set sio upper ;Extended Basic does not like lower case letters as input
sim> set sio ansi ;Extended Basic produces 8-bit output, strip to seven bits
sim> d sr 8 ;good setting for the Switch Register
sim> load exbas.bin 0 ;load it at 0
sim> go 0 ;and start it
16384 Bytes loaded at 0.
MEMORY SIZE? [return]
WANT SIN-COS-TAN-ATN? [Y]
50606 BYTES FREE
ALTAIR BASIC REV. 4.0
[EXTENDED VERSION]
COPYRIGHT 1977 BY MITS INC.
OK
3.11 Altair Disk Extended Basic Version 300-5-C
This version of Basic was provided by Scott LaBombard. To execute use the
following commands:
sim> d tracks[0-7] 77 ;set to Altair settings
sim> at dsk extbas5.dsk
sim> g 0
MEMORY SIZE? [return]
LINEPRINTER? [C]
HIGHEST DISK NUMBER? [0]
HOW MANY FILES? [3]
HOW MANY RANDOM FILES? [3]
42082 BYTES FREE
ALTAIR DISK EXTENDED BASIC
VERSION 300-5-C [01NOV78]
COPYRIGHT 1978 BY MITS INC.
OK
4. Special simulator features
In addition to the regular SIMH features such as PC queue, breakpoints
etc., this simulator supports memory access breakpoints. A memory access
breakpoint is triggered when a pre-defined memory location is accessed
(read, write or update). To set a memory location breakpoint enter
sim> break -m <location>
Execution will stop whenever an operation accesses <location>. Note that
a memory access breakpoint is not triggered by fetching code from memory
(this is the job of regular breakpoints). This feature has been
implemented by using the typing facility of the SIMH breakpoints.
5. Brief summary of all major changes to the original Altair simulator
- Full support for Z80. CP/M software requiring a Z80 CPU now runs
properly. DDTZ and PROLOGZ are included for demonstration purposes.
- Added banked memory support.
- PC queue implemented.
- Full assembler and dis-assembler support for Z80 and 8080 mnemonics.
Depending on the current setting of the CPU, the appropriate mnemonics
are used.
- The BOOT ROM was changed to fully load the software from disk. The
original code basically loaded a copy of itself from the disk and
executed it.
- ROM and memory size settings are now fully honored. This means that you
cannot write into the ROM or outside the defined RAM (e.g. when the RAM size
was truncated with the SET CPU commands). This feature allows programs which
check for the size of available RAM to run properly (e.g. 4k Basic). In
addition one can enable and disable the ROM which is useful in special cases
(e.g. when testing a new version of the ROM).
- The console can also be used via Telnet. This is useful when a terminal is
needed which supports cursor control such as a VT100. PROLOGZ for example
has a built-in screen editor which works under Telnet.
- Simplified file exchange for CP/M. Using the READ program under CP/M one
can easily import files into CP/M from the regular file system. Note that PIP
does not work properly on non-text files on PTR.
- The WRITE program can be used to transfer files from the CP/M environment to
the regular environment (binary or ASCII transfer).
- The last character read from PTR is always Control-Z (the EOF character for
CP/M). This makes sure that PIP (Peripheral Interchange Program on CP/M) will
terminate properly.
- Fixed a bug in the BIOS warm boot routine which caused CP/M to crash.
- Modified the BIOS for CP/M to support 8 disks.
- Added CP/M 3 banked version as sample software
- Changed from octal to hex
- Made the DSK and SIO device more robust (previously malicious code could
crash the simulator)
- Added memory access break points
- Added periodic timer interrupts (useful for MP/M)
- Added additional consoles (useful for MP/M)
- Added MP/M II banked version as sample software