1. Nova Simulator Usage

Date:

2020-04-28

Revision:

$Format:%H$

Copyright:

See LICENSE.txt for terms of use.

Copyright notice

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

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 THE AUTHORS 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 names of The Authors shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from the Authors.

This memorandum documents the Nova simulator.

1.1. 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

1.2. Nova features

The Nova simulator is configured as follows:

Device names	Simulates
CPU	Nova, Nova 3, Nova 4 CPU with 32KW of memory, or Keronix CPU with 64KW of memory
-	Hardware multiply/divide
PTR, PTP	Paper tape reader/punch
TTI, TTO	Console terminal
TTI1, TTO1	Second terminal
LPT	Line printer
PLT	Plotter
RTC	Real-time clock
DSK	Head-per-track disk controller
DKP	Moving head disk controller with four drives
MTA	Magnetic tape controller with eight drives
QTY	4060 multiplexer with up to 64 lines
ALM	4255 multiplexer 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 LOAD command supports standard binary format tapes. The DUMP command is not implemented.

All devices except TTI can be disabled or enabled, by the commands:

SET <dev> DISABLED
SET <dev> ENABLED

All devices except QTY are enabled by default.

1.2.1. CPU

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

SET CPU MDV	Enable multiply/divide [1]
SET CPU EXT64KW	Enable extended 64KW memory mode
SET CPU NOVA3	Set Nova3 CPU [2]
SET CPU NOVA4	Set Nova4 CPU [3]
SET CPU KERONIX	Set Keronix CPU [4]
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
SET CPU 36K	Set memory size = 36K
SET CPU 40K	Set memory size = 40K
SET CPU 44K	Set memory size = 44K
SET CPU 48K	Set memory size = 48K
SET CPU 52K	Set memory size = 52K
SET CPU 56K	Set memory size = 56K
SET CPU 60K	Set memory size = 60K
SET CPU 64K	Set memory size = 64K

[1]

MDV = unsigned multiply/divide instructions

[2]

Nova 3 = unsigned multiply/divide, stack, trap instructions

[3]

Nova 4 = unsigned and signed multiply/divide, stack, byte, trap instructions

[4]

Keronix = unsigned multiply/divide, extended 64KW mode

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	16	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

The CPU can maintain a history of the most recently executed instructions. This is controlled by the SET CPU HISTORY and SHOW CPU HISTORY commands:

SET CPU HISTORY	Clear history buffer
SET CPU HISTORY=0	Disable history
SET CPU HISTORY=n	Enable history, length = n
SHOW CPU HISTORY	Print CPU history
SHOW CPU HISTORY=n	Print first n entries of CPU history

The maximum length for the history is 65536 entries.

1.2.2. Programmed I/O devices

1.2.2.1. 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
end of file	1	Report error and stop
	0	Out of tape
OS I/O error	x	Report error and stop

1.2.2.2. 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
OS I/O error	x	Report error and stop

1.2.2.3. 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

1.2.2.4. Terminal output (TTO)

The terminal output writes to the simulator console window. Terminal output 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 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

1.2.2.5. 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 default position after ATTACH is to position at the end of an existing file. A new file can be created if you attach with the -N switch.

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

1.2.2.6. Real-time clock (RTC)

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

SET RTC 60HZ	Set line frequency to 60Hz
SET RTC 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.

1.2.2.7. Plotter (PLT)

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 paper
OS I/O error	x	Report error and stop

1.2.2.8. 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 remains open 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.

Other special TTI1 commands:

SHOW TTI1 CONNECTIONS	Show current connections
SHOW TTI1 STATISTICS	Show statistics for active connections
SET TTO1 DISCONNECT	Disconnects the line

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

1.2.2.9. Asynchronous multiplexers (QTY, ALM)

The QTY and ALM are terminal multiplexers 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

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>

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

Once the multiplexer is attached and the simulator is running, it listens 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.

Other special QTY/ALM commands:

SHOW {QTY|ALM} CONNECTIONS	Show current connections
SHOW {QTY|ALM} STATISTICS	Show statistics for active connections
SET {QTY|ALM} DISCONNECT=n	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 multiplexers do not support save and restore. All open connections are lost when the simulator shuts down or the multiplexer is detached.

1.2.3. Fixed head disk (DSK)

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 DSK 1P	One platter (256K)
SET DSK 2P	Two platters (512K)
SET DSK 3P	Three platters (768K)
SET DSK 4P	Four platters (1024K)
SET DSK 5P	Five platters (1280K)
SET DSK 6P	Six platters (1536K)
SET DSK 7P	Seven platters (1792K)
SET DSK 8P	Eight platters (2048K)
SET DSK AUTOSIZE	Autosized on ATTACH

The default is 1P (minimum size). The fixed head disk controller supports the BOOT command.

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.

1.2.4. Moving head disk (DKP)

Moving head disk options include the ability to make units write enabled or write locked, and to select the type of drive (or autosize):

SET DKPn LOCKED	Set unit n write locked
SET DKPn WRITEENABLED	Set unit n write enabled
SET DKPn FLOPPY (or 6030)	Set unit n to floppy disk
SET DKPn DSDD (or 6097)	Set unit n to double density floppy
SET DKPn D31 (or 4047)	Set unit n to Diablo 31
SET DKPn D44 (or 4234, 6045)	Set unit n to Diablo 44
SET DKPn C111 (or 4048)	Set unit n to Century 111
SET DKPn C114 (or 2314, 4057)	Set unit n to Century 114
SET DKPn 6225	Set unit n to 6225
SET DKPn 6099	Set unit n to 6099
SET DKPn 6227	Set unit n to 6227
SET DKPn 6070	Set unit n to 6070
SET DKPn 6103	Set unit n to 6103
SET DKPn 4231 (or 3330)	Set unit n to 4231
SET DKPn AUTOSIZE	Set type based on file size at ATTACH

Units can also be set ENABLED or DISABLED. The moving head disk controller supports the BOOT command.

All drives have 256 16b words per sector. The other disk parameters are:

Drive	Cyl	Surf	Sectors	Size (MW)	Model numbers
floppy	77	1	8	.158	6030
dsdd floppy	77	2	16	.632	6097
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	2314, 4057
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	3330

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

1.2.5. Magnetic tape (MTA)

Magnetic tape options include the ability to make units write enabled or write locked.

SET MTAn LOCKED	Set unit n write locked
SET MTAn WRITEENABLED	Set unit n write enabled

Magnetic tape units can be set to a specific reel capacity in MB, or to unlimited capacity:

SET MTAn CAPAC=m	Set unit n capacity to m MB (0 = unlimited)
SHOW MTAn CAPAC	Show unit n capacity in MB

Units can also be set ENABLED or DISABLED. 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 to 7
POS[0:7]	31	Position, units 0 to 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

1.3. 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 packed ASCII characters
-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 packed ASCII characters
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.