NOVA/nova_doc.txt

To:	Users
From:	Bob Supnik
Subj:	Nova Simulator Usage
Date:	15-Mar-2004

			COPYRIGHT NOTICE

The following copyright notice applies to both the SIMH source and binary:

   Original code published in 1993-2004, written by Robert M Supnik
   Copyright (c) 1993-2004, 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 Nova simulator.


1. Simulator Files

sim/		scp.h
		sim_console.h
		sim_defs.h
		sim_fio.h
		sim_rev.h
		sim_sock.h
		sim_tape.h
		sim_timer.h
		sim_tmxr.h
		scp.c
		sim_console.c
		sim_fio.c
		sim_sock.c
		sim_tape.c
		sim_timer.c
		sim_tmxr.c

sim/nova/	nova_defs.h
		nova_cpu.c
		nova_clk.c
		nova_dkp.c
		nova_dsk.c
		nova_lp.c
		nova_mta.c
		nova_plt.c
		nova_qty.c
		nova_sys.c
		nova_tt.c
		nova_tt1.c

2. Nova Features

The Nova simulator is configured as follows:

device		simulates
name(s)

CPU		Nova, Nova 3, or Nova 4 CPU with 32KW of memory
-		hardware multiply/divide
PTR,PTP		paper tape reader/punch
TTI,TTO		console terminal
TTI1,TTO1	second terminal
LPT		line printer
PLT		plotter
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
QTY		4060 multiplexor with up to 64 lines
ALM		4255 multiplexor with up to 64 lines

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

Note that indirect address loop detection does not exist on unmapped
Novas.  Some DG diagnostics test thousands of levels of indirect
addressing.  INDMAX may have to be set to 32,000 to get diagnostics
to run properly.

The Nova loader supports standard binary format tapes.  The DUMP command
is not implemented.

Most devices can be disabled or enabled, by the commands:

	SET <dev> DISABLED
	SET <dev> ENABLED

All devices are enabled by default.

2.1 CPU

The only CPU options are the presence of the optional instructions
and the size of main memory.

	SET CPU MDV		enable multiply/divide
	SET CPU NOVA3		enable Nova3 instructions
	SET CPU NOVA4		enable Nova4 instructions
	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

(MDV = unsigned multiply/divide instructions)
(Nova 3 = unsigned multiply/divide, stack, trap instructions)
(Nova 4 = unsigned and signed multiply/divide, stack, byte, trap 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.

The CPU supports the boot command.  BOOT CPU simulates the Nova hardware
APL (automatic program load) feature.  The switch register (SR) bits 12:17
must contain the device code of the device to be booted.  If the device is
a "high-speed" (channel) device, SR bit 0 should also be set.  

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
	PCQ[0:63]	15	PC prior to last JMP, JMS, or interrupt;
				most recent PC change first
	WRU		8	interrupt character

2.2 Programmed I/O Devices

2.2.1 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		32	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 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

2.2.2 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		32	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

2.2.3 Terminal Input (TTI)

The terminal input polls the console keyboard for input.  Terminal
input options include the ability to set ANSI mode or limited Dasher
compatibility mode:

	SET TTI ANSI		normal mode
	SET TTI 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		32	number of characters input
	TIME		24	keyboard polling interval

2.2.4 Terminal Output (TTO)

The terminal output writes to the simulator console window.  Terminal
output options include the the ability to set ANSI mode or limited
Dasher compatibility 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		32	number of characters output
	TIME		24	time from I/O initiation to interrupt

2.2.5 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 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		32	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

2.2.6 Real-Time Clock (CLK)

The real-time clock (CLK) line frequency can be adjusted as follows:

	SET CLK 60HZ		set line frequency to 60Hz
	SET CLK 50HZ		set line frequency to 50Hz

The default is 60Hz.

The clock 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

The real-time clock autocalibrates; the clock interval is adjusted up
or down so that the clock tracks actual elapsed time.

2.2.7 Plotter (PTP)

The plotter (PLT) 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 plotter.

The plotter 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		32	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

2.2.8 Second Terminal (TTI1, TTO1)

The second terminal consists of two independent devices, TTI1 and TTO1.
The additional terminal performs input and output through a Telnet session
connecting into a user-specified port.  The ATTACH command specifies the
port to be used:

	ATTACH TTI1 <port>	set up listening port

where port is a decimal number between 1 and 65535 that is not being used
for other TCP/IP activities.

Once TTI1 is attached and the simulator is running, the terminal listens
for a connection on the specified port.  It assumes that the incoming
connection is a Telnet connection.  The connection remain opens until
disconnected by the Telnet client, or by a DETACH TTI1 command.

The second terminal has two options, recognized on both devices, for
setting limited Dasher-compatibility mode or ANSI mode:

	SET TTI1 ANSI		normal mode
	SET TTI1 DASHER		Dasher mode
	SET TTO1 ANSI		normal mode
	SET TTO1 DASHER		Dasher mode

Setting either TTI1 or TTO1 changes both devices.  In Dasher mode, carriage
return is changed to newline on input, and ^X is changed to backspace.
TTO1 supports output logging.  The SET TTO1 LOG command enables logging:

	SET TTO1 LOG=filename	log output to filename

The SET TTO1 NOLOG command disables logging and closes the open log
file, if any.

The SHOW TTI1 CONNECTIONS command displays the current connection to TTI1.
The SHOW TTI1 STATISTICS command displays statistics for the current connection.
The SET TTI1 DISCONNECT{=0} disconnects the current connection.

The second 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
	TIME		24	keyboard polling interval

The second 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
	TIME		24	time from I/O initiation to interrupt

2.2.8 Asynchronous Multiplexors (QTY, ALM)

The QTY and ALM are terminal multiplexors with up to 64 lines.  Either
the QTY or ALM can be enabled, but not both; the ALM is enabled by
default.  The number of lines can be changed with the command

	SET {QTY|ALM} LINES=n	set line count to n

The line count maximum is 64.

The QTY and ALM support 8-bit input and output of characters.  8-bit I/O
may be incompatible with certain operating systems; 7-bit is the default.
The command

	SET {QTY|ALM} 8B

enables 8-bit input and output.

The terminal lines perform input and output through Telnet sessions
connected to a user-specified port.  The ATTACH command specifies
the port to be used:

	ATTACH {-am} {QTY|ALM} <port>	set up listening port

where port is a decimal number between 1 and 65535 that is not being used
for other TCP/IP activities.  For the ALM multiplexor, the optional switch
-m turns on the multiplexor modem controls; the optional switch -a turns on
active disconnects (disconnect session if computer clears Data Terminal Ready).
The QTY multiplexor does not support modem control.  Without modem control,
the multiplexor behaves as though terminals were directly connected;
disconnecting the Telnet session does not cause any operating system-
visible change in line status.

Once the multiplexor is attached and the simulator is running, it will listen
for connections on the specified port.  It assumes that the incoming
connections are Telnet connections.  The connection remains open until
disconnected by the simulated program, the Telnet client, a SET {QTY|ALM}
DISCONNECT command, or a DETACH {QTY|ALM} command.

The SHOW {QTY|ALM} CONNECTIONS command displays the current connections to
the multiplexor.  The SHOW {QTY|ALM} STATISTICS command displays statistics
for active connections.  The SET {QTY|ALM| DISCONNECT=linenumber disconnects
the specified line.

The QTY/ALM implement these registers:

	name		size	comments

	BUF		8	character buffer
	BUSY		1	device busy flag
	DONE		1	device done flag
	DISABLE		1	device disable flag
	INT		1	interrupt pending flag
	MDMCTL		1	modem control flag
	AUTODS		1	autodisconnect flag
	POLLS		32	number of service polls
	STOP_IOE	1	stop on I/O error

The multiplexors do not support save and restore.  All open connections are
lost when the simulator shuts down or the multiplexor is detached.

2.3 Fixed Head Disk (DK)

Fixed head disk options include the ability to set the number of platters
to a fixed value between 1 and 8, or to autosize the number of platters
from the attached file:

	SET RF 1P		one platter (256K)
	SET RF 2P		two platters (512K)
	SET RF 3P		three platters (768K)
	SET RF 4P		four platters (1024K)
	SET RF 5P		five platters (1280K)
	SET RF 6P		six platters (1536K)
	SET RF 7P		seven platters (1792K)
	SET RF 8P		eight platters (2048K)
	SET RF AUTOSIZE		autosized on attach

The default is 1P (minimum size).

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

The fixed head disk controller supports the BOOT command.

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.

2.4 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 WRITEENABLED	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 set ONLINE or OFFLINE.  The moving head disk controller
supports the BOOT command.

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	245	2	20	 2.508
	6099	192	4	32	 6.291
	6227	245	6	20	 7.526
	6070	408	4	24	10.027
	6103	192	8	32	12.583
	4231	411	19	23	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
	DIAG		1	diagnostic mode flag
	MAP		2	map select
	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

2.5 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 WRITEENABLED	set unit n write enabled

Units can also be set ONLINE or OFFLINE.  The magnetic tape controller
supports the BOOT command.

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
	UST[0:7]	32	unit status, units 0-7
	POS[0:7]	31	position, units 0-7

Error handling is as follows:

	error			processed as

	not attached		tape not ready

	end of file		bad tape

	OS I/O error		report error and stop

2.6 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.