WHAT'S NEW since simh v3.9
. . New Simulators
. . Simulator Front Panel API
. . New Functionality
. . . . DDCMP Synchronous host physical device support - framer
. . . . Remote Console Facility
. . . . VAX/PDP11 Enhancements
. . . . PDP11 Specific Enhancements
. . . . PDP10 Enhancements
. . . . SDS 940 Enhancements
. . . . Terminal Multiplexer additions
. . . . Video Display Capabilities
. . . . Asynchronous I/O
. . . . Clock/Timer Enhancements
. . . . Ethernet Transport Enhancements
. . . . Disk Extensions
. . . . Embedded ROM support
. . . . Control Flow
. . . . Scriptable interactions with running simulators
. . . . Help
. . . . Generic SCP support Clock Coscheduling as opposed to per simulator implementations
. . . . New SCP Commands
. . . . Command Processing Enhancements
. . . . . . Environment variable insertion
. . . . . . Command aliases
. . . . . . Do command argument manipulation
. . Building and running a simulator
. . . . Use Prebuilt Windows Simulators
. . . . Building simulators yourself
. . . . . . Linux/OSX other *nix platforms
. . . . . . . . Build Dependencies
. . . . . . . . . . OS X - Dependencies
. . . . . . . . . . Linux - Dependencies
. . . . . . Windows
. . . . . . . . Required related files
. . . . . . . . Visual Studio (Standard or Express) 2008, 2010, 2012, 2013 or Visual Studio Community 2015, 2017, 2019
. . . . . . . . MinGW32
. . . . . . VMS
. . Problem Reports
Leonid Broukhis and Serge Vakulenko have implemented a simulator for the Soviet mainframe BESM-6 computer.
VAX-11/730
VAX-11/750
VAX 8200/8250
VAX 8600/8650
MicroVAX I & VAXstation I
MicroVAX II & VAXstation II & VAXstation II/GPX
rtVAX 1000 (or Industrial VAX 620)
MicroVAX 2000 & VAXstation 2000
MicroVAX 3100 M10/M20
MicroVAX 3100 M10e/M20e
InfoServer 100
InfoServer 150 VXT
VAXstation 3100 M30
VAXstation 3100 M38
VAXstation 3100 M76
VAXstation 4000 VLC
VAXstation 4000 M60
MicroVAX 3100 M80
InfoServer 1000
Gerardo Ospina has implemented a Manchester University SSEM (Small Scale Experimental Machine) simulator.
Richard Cornwell has implemented the IBM 701, IBM 704, IBM 7010/1410, IBM 7070/7074, IBM 7080/702/705/7053 and IBM 7090/7094/709/704 simulators.
Richard Cornwell has implemented the PDP6, PDP10-KA, PDP10-KI, PDP10-KL and PDP10-KS simulators. With the differences merely being some device name changes, the PDP10-KS should be compatible with Bob Supnik's original PDP10 simulator.
The sim_frontpanel API provides a programmatic interface to start and control any simulator without any special additions to the simulator code.
Paul Koning has implemented a USB hardware device which can interface transport DDCMP packets across a synchronous line to physical host systems with native synchronous devices or other simulators using framer devices.
A new capability has been added which allows a TELNET Connection to a user designated port so that some out of band commands can be entered to manipulate and/or adjust a running simulator. The commands which enable and control this capability are SET REMOTE TELNET=port, SET REMOTE CONNECTIONS=n, SET REMOTE TIMEOUT=seconds, and SHOW REMOTE.
The remote console facility has two modes of operation: 1) single command mode. and 2) multiple command mode.
In single command mode you enter one command at a time and aren't concerned about what the simulated system is doing while you enter that command. The command is executed once you've hit return.
In multiple command mode you initiate your activities by entering the WRU character (usually ^E). This will suspend the current simulator execution. You then enter commands as needed and when you are done you enter a CONTINUE command. While entering Multiple Command commands, if you fail to enter a complete command before the timeout (specified by "SET REMOTE TIMEOUT=seconds"), a CONTINUE command is automatically processed and simulation proceeds.
A subset of normal simh commands are available for use in remote console sessions. The Single Command Mode commands are: ATTACH, DETACH, PWD, SHOW, DIR, LS, ECHO, HELP The Multiple Command Mode commands are: EXAMINE, IEXAMINE, DEPOSIT, EVALUATE, ATTACH, DETACH, ASSIGN, DEASSIGN, STEP, CONTINUE, PWD, SAVE, SET, SHOW, DIR, LS, ECHO, HELP
A remote console session will close when an EOF character is entered (i.e. ^D or ^Z).
RQ has new disk types: RC25, RCF25, RA80
RQ device has a settable controller type (RQDX3, UDA50, KLESI, RUX50)
RQ disks default to Autosize without regard to disk type
RQ disks on PDP11 can have RAUSER size beyond 2GB
DMC11/DMR11 DDCMP DECnet device simulation. Up to 8 DMC devices are supported. Packet transport is via TCP or UDP connections.
KDP11 on PDP11 for DECnet
DUP11 on PDP11 for DECnet connectivity to talk to DMC, KDP or other DUP devices
CH11 on PDP11 and VAX780 for Chaosnet (from Lars Brinkhoff)
DZ on Unibus systems can have up to 256 ports (default of 32), on
Qbus systems 128 port limit (default of 16).
DZ devices optionally support full modem control (and port speed settings
when connected to serial ports).
TU58 device support for all PDP11 and VAX systems.
DHU11 (device VH) on Unibus systems now has 16 ports per multiplexer.
XQ devices (DEQNA, DELQA and DELQA-T) are bootable on Qbus PDP11 simulators
XQ and XU devices (DEQNA, DELQA, DELQA-T, DEUNA and DELQA) devices can now
directly communicate to a remote device via UDP (i.e. a built-in HECnet bridge).
XQ and XU devices (DEQNA, DELQA, DELQA-T, DEUNA and DELQA) devices can now
optionally throttle outgoing packets which is useful when communicating with
legacy systems (real hardware) on a local LAN which can easily get over run
when packets arrive too fast.
MicroVAX 3900 has QVSS (VCB01) board available.
MicroVAX 3900 and MicroVAX II have SET CPU AUTOBOOT option
MicroVAX 3900 has a SET CPU MODEL=(MicroVAX|VAXserver|VAXstation) command to change between system types
MicroVAX I has a SET CPU MODEL=(MicroVAX|VAXSTATION) command to change between system types
MicroVAX II has a SET CPU MODEL=(MicroVAX|VAXSTATION) command to change between system types
ROM (from Lars Brinkhoff) I/O page ROM support
NG (from Lars Brinkhoff) Knight vector display
DAZ (from Lars Brinkhoff) Dazzle Dart Input device
KDP11 (from Timothe Litt) for DECnet connectivity to simulators with DMC, DUP or KDP devices
DMR11 for DECnet connectivity to simulators with DMC, DUP or KDP devices on TOPS10.
CH11 (from Lars Brinkhoff) Chaosnet interface.
Support for SDS internal ASCII character encoding during display and data entry.
Allow breakpoints to be qualified by normal, monitor or user mode.
Fix CPU, RAD, MUX and I/O bugs that prevented SDS Time Share System Monitor and Executive from executing properly.
Added support for TCP connections using IPv4 and/or IPv6.
Logging - Traffic going out individual lines can be optionally logged to
files
Buffering - Traffic going to a multiplexor (or Console) line can
optionally be buffered while a telnet session is not connected
and the buffered contents will be sent out a newly connecting
telnet session. This allows a user to review what may have
happened before they connect to that session.
Serial Port support based on work by J David Bryan and Holger Veit
Serial Console Support
Separate TCP listening ports per line
Outgoing connections per line (virtual Null Modem cable).
Packet sending and reception semantics for simulated network device support using either TCP or UDP transport.
Input character rates reflect the natural character arrival time based on the line speed.
Added support for monochrome and color displays with optional keyboards and mice.
The VAXstation QVSS device (VCB01) and QDSS device (VCB02) simulations use these capabilities.
Host platforms which have libSDL2 available can leverage this functionality.
* Disk and Tape I/O can be asynchronous. Asynchronous support exists
for pdp11_rq, pdp11_rp and pdp11_tq devices (used by VAX and PDP11
simulators).
* Multiplexer I/O (Telnet and/or Serial) can be asynchronous.
Asynchronous support exists for console I/O and most multiplexer
devices. (Still experimental - not currently by default)
* Asynchronous clocks ticks exist to better support modern processors
that have variable clock speeds. The initial clock calibration model
presumed a constant simulated instruction execution rate.
Modern processors have variable processor speeds which breaks this
key assumption.
* Strategies to make up for missed clock ticks are now available
(independent of asynchronous tick generation). These strategies
generate catch-up clock ticks to keep the simulator passage of
time consistent with wall clock time. Simulator time while idling
or throttling is now consistent. Reasonable idling behavior is
now possible without requiring that the host system clock tick be
10ms or less.
* Simulator writers have access to timing services and explicit wall
clock delays where appropriate.
* UDP packet transport. Direct simulator connections to HECnet can be
made without running a local packet bridge program.
* NAT packet transport. Simulators which only speak TCP/IP (No DECnet)
and want to communicate with their host systems and/or directly to
the Internet can use NAT packet transport. This also works for WiFi
connected host systems.
* Packet Transmission Throttling. When connected to a LAN which has
legacy network adapters (DEQNA, DEUNA) on legacy systems, it is very
easy for a simulated system to overrun the receiving capacity of the
older systems. Throttling of simulated traffic delivered to the LAN
can be used to mitigate this problem.
* Reliable MAC address conflict detection.
* Automatic unique default MAC address assignment.
RAW Disk Access (including CDROM)
Virtual Disk Container files, including differencing disks
File System type detection to accurately autosize disks.
Recognized file systems are: DEC ODS1, DEC ODS2, DEC RT11, DEC RSTS, DEC RSX11, Ultrix Partitions, ISO 9660
AWS format tape support
TAR format tape support
ANSI-VMS, ANSI-RSX11, ANSI-RSTS, ANSI-RT11 format tape support
Simulators which have boot commands which load constant files as part of
booting have those files imbedded into the simulator executable. The
imbedded files are used if the normal boot file isn't found when the
simulator boots. Specific examples are:
VAX (MicroVAX 3900 - ka655x.bin)
VAX8600 (VAX 8600 - vmb.exe)
VAX780 (VAX 11/780 - vmb.exe)
VAX750 (VAX 11/750 - vmb.exe, ka750_old.bin, ka750_new.bin),
VAX730 (VAX 11/730 - vmb.exe)
VAX610 (MicroVAX I - ka610.bin)
VAX620 (rtVAX 1000 - ka620.bin)
VAX630 (MicroVAX II - ka630.bin)
The following extensions to the SCP command language without affecting prior behavior:
GOTO <Label> Command is now available. Labels are lines
in which the first non whitespace character
is a ":". The target of a goto is the first
matching label in the current do command
file which is encountered. Since labels
don't do anything else besides being the
targets of goto's, they could be used to
provide comments in do command files, for
example (":: This is a comment")
RETURN {status} Return from the current do command file
execution with the specified status or
the status from the last executed command
if no status is specified. Status can be
a number or a SCPE_<conditionname> name
string.
SET ON Enables error trapping for currently defined
traps (by ON commands)
SET NOON Disables error trapping for currently
defined traps (by ON commands)
ON <statusvalue> commandtoprocess{; additionalcommandtoprocess}
Sets the action(s) to take when the specific
error status is returned by a command in the
currently running do command file. Multiple
actions can be specified with each delimited
by a semicolon character (just like
breakpoint action commands).
ON ERROR commandtoprocess{; additionalcommandtoprocess}
Sets the default action(s) to take when any
otherwise unspecified error status is returned
by a command in the currently running do
command file. Multiple actions can be
specified with each delimited by a semicolon
character (just like breakpoint action
commands).
ON CONTROL_C commandtoprocess{; additionalcommandtoprocess}
Specifies particular actions to perform when
the operator enters CTRL+C while a command
procedure is running. The default action is
to exit the current and any nested command
procedures and return to the sim> input prompt.
ON <statusvalue> Clears the action(s) to take when condition occurs
ON ERROR Clears the default actions to take when any
otherwise unspecified error status is
returned by a command in the currently
running do command file.
ON CONTROL_C
Restores the default CTRL+C behavior for the
currently running command procedure.
DO <stdin>
Invokes a nested DO command with input from the
running console.
Error traps can be taken for any command which returns a status other than SCPE_STEP, SCPE_OK, and SCPE_EXIT.
ON Traps can specify any status value from the following list: NXM, UNATT, IOERR, CSUM, FMT, NOATT, OPENERR, MEM, ARG, STEP, UNK, RO, INCOMP, STOP, TTIERR, TTOERR, EOF, REL, NOPARAM, ALATT, TIMER, SIGERR, TTYERR, SUB, NOFNC, UDIS, NORO, INVSW, MISVAL, 2FARG, 2MARG, NXDEV, NXUN, NXREG, NXPAR, NEST, IERR, MTRLNT, LOST, TTMO, STALL, AFAIL, NOTATT, AMBREG. These values can be indicated by name or by their internal numeric value (not recommended).
Interactions with ASSERT command and "DO -e":
DO -e is equivalent to SET ON, which by itself it equivalent
to "SET ON; ON ERROR RETURN".
ASSERT failure have several different actions:
* If error trapping is not enabled then AFAIL causes exit from
the current do command file.
* If error trapping is enabled and an explicit "ON AFAIL"
action is defined, then the specified action is performed.
* If error trapping is enabled and no "ON AFAIL" action is
defined, then an AFAIL causes exit from the current do
command file.
Other related changes/extensions: The "!" command (execute a command on the local OS), now returns the command's exit status as the status from the "!" command. This allows ON conditions to handle error status responses from OS commands and act as desired.
The EXPECT command now exists to provide a means of reacting to simulator output and the SEND command exists to inject data into programs running within a simulator.
EXPECT {HALTAFTER=n,}"\r\nPassword: "
SEND {AFTER=n,}{DELAY=m,}"mypassword\r"
or
EXPECT {HALTAFTER=n,}"\r\nPassword: " SEND {AFTER=n,}{DELAY=m,}"mypassword\r"; GO
The built-in help system provides a heirarchical oriented help command interface.
In addition, there is explicit support for per device help:
HELP dev
HELP dev ATTACH
HELP dev SET (aka HELP SET dev)
HELP dev SHOW (aka HELP SHOW dev)
HELP dev REGISTERS
Device simulator authors can easily schedule their device polling activities to allow for efficient simulator execution when polling for device activity while still being well behaved when their simulated system is actually idle.
SCREENSHOT filename.bmp Save video window to the specified file
SET ENV Name=Value Set Environment variable
SET ENV -p "Prompt" Name=Default Gather User input into an Environment Variable
SET ENV -a Name=Expression Evaluate an expression and store result in an Environment Variable
SET ASYNCH Enable Asynchronous I/O
SET NOASYNCH Disable Asynchronous I/O
SET VERIFY Enable command display while processing DO command files
SET NOVERIFY Enable command display while processing DO command files
SET MESSAGE Enable error message output when commands complete (default)
SET NOMESSAGE Disable error message output when commands complete
SET QUIET Set minimal output mode for command execution
SET NOQUIET Set normal output mode for command execution
SET PROMPT Change the prompt used by the simulator (default sim>)
SET THROTTLE x/t Throttle t ms every x cycles
SET REMOTE TELNET=port Specify remote console telnet port
SET REMOTE NOTELNET Disables remote console
SET REMOTE CONNECTIONS=n Specify the number of concurrent remote console sessions
SHOW FEATURES Displays the devices descriptions and features
SHOW ASYNCH Display the current Asynchronous I/O status
SHOW SERIAL Display the available and/or open serial ports
SHOW ETHERNET Display the available and/or open ethernet connections
SHOW MULTIPLEXER Display the details about open multiplexer devices
SHOW CLOCKS Display the details about calibrated timers
SHOW REMOTE Display the remote console configuration
SHOW ON Display ON condition dispatch actions
SET ON Enable ON condition error dispatching
SET NOON Disable ON condition error dispatching
GOTO Transfer to label in the current DO command file
CALL Call subroutine at indicated label
RETURN Return from subroutine call
SHIFT Slide argument parameters %1 thru %9 left 1
NOOP A no-op command
ON Establish or cancel an ON condition dispatch
IF Test some simulator state and conditionally execute commands
IF (C-style-expression) Test some simulator state and conditionally execute commands
ELSE commands to execute when the previous IF wasn't true
CD Change working directory
SET DEFAULT Change working directory
PWD Show working directory
SHOW DEFAULT Show working directory
DIR {path|file} Display file listing
LS {path|file} Display file listing
NEXT Step across a subroutine call or step a single instruction.
EXPECT React to output produced by a simulated system
SEND Inject input to a simulated system's console
SLEEP time Pause command execution for specified time
SCREENSHOT Snapshot the current video display window
RUN UNTIL breakpoint Establish the breakpoint specified and run until it is encountered
RUN UNTIL "output-string" ... Establish the specified "output-string" as an EXPECT and run until it is encountered.
GO UNTIL breakpoint Establish the breakpoint specified and go until it is encountered
GO UNTIL "output-string" ... Establish the specified "output-string" as an EXPECT and go until it is encountered.
RUNLIMIT Bound simulator execution time
TAR Manipulate file archives
CURL Access URLs from the web
Built In variables %DATE%, %TIME%, %DATETIME%, %LDATE%, %LTIME%, %CTIME%, %DATE_YYYY%, %DATE_YY%, %DATE_YC%, %DATE_MM%, %DATE_MMM%, %DATE_MONTH%, %DATE_DD%, %DATE_D%, %DATE_WYYYY%, %DATE_WW%, %TIME_HH%, %TIME_MM%, %TIME_SS%, %STATUS%, %TSTATUS%, %SIM_VERIFY%, %SIM_QUIET%, %SIM_MESSAGE%
Token "%0" expands to the command file name. Token %n (n being a single digit) expands to the n'th argument Token %* expands to the whole set of arguments (%1 ... %9)
The input sequence "%%" represents a literal "%". All other character combinations are rendered literally.
Omitted parameters result in null-string substitutions.
Tokens preceded and followed by % characters are expanded as environment variables, and if an environment variable isn't found then it can be one of several special variables:
%DATE% yyyy-mm-dd
%TIME% hh:mm:ss
%DATETIME% yyyy-mm-ddThh:mm:ss
%LDATE% mm/dd/yy (Locale Formatted)
%LTIME% hh:mm:ss am/pm (Locale Formatted)
%CTIME% Www Mmm dd hh:mm:ss yyyy (Locale Formatted)
%UTIME% nnnn (Unix time - seconds since 1/1/1970)
%DATE_YYYY% yyyy (0000-9999)
%DATE_YY% yy (00-99)
%DATE_MM% mm (01-12)
%DATE_MMM% mmm (JAN-DEC)
%DATE_MONTH% month (January-December)
%DATE_DD% dd (01-31)
%DATE_WW% ww (01-53) ISO 8601 week number
%DATE_WYYYY% yyyy (0000-9999) ISO 8601 week year number
%DATE_D% d (1-7) ISO 8601 day of week
%DATE_JJJ% jjj (001-366) day of year
%DATE_19XX_YY% yy A year prior to 2000 with the same
calendar days as the current year
%DATE_19XX_YYYY% yyyy A year prior to 2000 with the same
calendar days as the current year
%TIME_HH% hh (00-23)
%TIME_MM% mm (00-59)
%TIME_SS% ss (00-59)
%STATUS% Status value from the last command executed
%TSTATUS% The text form of the last status value
%SIM_VERIFY% The Verify/Verbose mode of the current Do command file
%SIM_VERBOSE% The Verify/Verbose mode of the current Do command file
%SIM_QUIET% The Quiet mode of the current Do command file
%SIM_MESSAGE% The message display status of the current Do command file
Environment variable lookups are done first with the precise name between the % characters and if that fails, then the name between the % characters is upcased and a lookup of that values is attempted.
The first Space delimited token on the line is extracted in uppercase and then looked up as an environment variable. If found it the value is substituted for the original string before expanding everything else. If it is not found, then the original beginning token on the line is left untouched.
Commands can be aliases with environment variables. For example:
sim> set env say=echo
sim> say Hello there
Hello there
The SHIFT command will shift the %1 thru %9 arguments to the left one position.
Simulators for the Windows platform are built and made available on a regular basis (at least once a week if substantive changes have been made to the codebase).
The prebuilt Windows binaries will run on all versions of Microsoft Windows from Windows XP onward.
They can be accessed at https://github.com/simh/Win32-Development-Binaries
Several relatively recent versions should be available which you can download and use directly.
First download the latest source code from the github repository's master branch at https://github.com/simh/simh/archive/master.zip
Depending on your host platform one of the following steps should be followed:
If you are interested in using a simulator with Ethernet networking support (i.e. one of the VAX simulators or the PDP11), then you should make sure you have the correct networking components available. The instructions in https://github.com/simh/simh/blob/master/0readme_ethernet.txt describe the required steps to get ethernet networking components installed and how to configure your environment.
See the 0readme_ethernet.txt file for details about the required network components for your platform. Once your operating system build environment has the correct networking components available the following command will build working simulators:
$ make {simulator-name (i.e. vax)}
The makefile provided requires GNU make, which is the default make facility for most systems these days. Any host system which doesn't have GNU make available as the default make facility may have it installed as 'gmake'. GNU make (gmake) is generally available an installation package for all current operating systems which have a package installation system.
Some simulators depend on external packages to provide the full scope of functionality they may be simulating. These additional external packages may or may not be included in as part of the standard Operating System distributions. If simulators are being built that could provide more functionality than the currently installed packages will provide, the build will succeed with reduced functionality (i.e. limited network or no video support), but suggestions will be provided as to what could provide full functionality.
The MacPorts package manager is available to provide these external packages. Once MacPorts is installed, these commands will install the required dependent packages:
# port install vde2
# port install libsdl2
# port install libsdl2_ttf
OR
The HomeBrew package manager can be used to provide these packages:
$ brew install vde
$ brew install sdl2
$ brew install sdl2_ttf
Different Linux distributions have different package management systems:
Ubuntu:
# apt-get install libpcap-dev
# apt-get install libpcre3-dev
# apt-get install vde2
# apt-get install libsdl2-dev
# apt-get install libsdl2_ttf-dev
Compiling on windows is supported with recent versions of Microsoft Visual Studio (Standard or Express) and using GCC via the MinGW32 environment. Things may also work under Cygwin, but that is not the preferred windows environment. Not all features will be available as well as with either Visual Studio or MinGW32.
The file https://github.com/simh/simh/blob/master/Visual%20Studio%20Projects/0ReadMe_Projects.txt
Visual Studio (Standard or Express) 2008, 2010, 2012, 2013 or Visual Studio Community 2015, 2017, 2019
The file https://github.com/simh/simh/blob/master/Visual%20Studio%20Projects/0ReadMe_Projects.txt describes the required steps to use the setup your environment to build using Visual Studio.
Building with MinGW32 requires the same directory organization and the dependent package support described for Visual Studio in the file https://github.com/simh/simh/blob/master/Visual%20Studio%20Projects/0ReadMe_Projects.txt. Building with MinGW64 is not supported.
Download the latest source code as a zip file from: https://github.com/simh/simh/archive/master.zip
Unzip it in the directory that you want SIMH to reside in. Unpack it and set the file attributes as follows:
$ unzip simh-master.zip
$ set default [.simh-master]
$ set file/attri=RFM:STM makefile,*.mms,[...]*.c,[...]*.h,[...]*.txt
Simulators with ethernet network devices (All the VAX simulators and the PDP11) can have functioning networking when running on Alpha or IA64 OpenVMS.
In order to build and run simulators with networking support, the VMS-PCAP
package must be available while building your simulator. The simh-vms-pcap.zip
file can be downloaded from https://github.com/simh/simh/archive/vms-pcap.zip
This link will return a file called simh-vms-pcap.zip which should be unpacked as follows:
$ unzip -a simh-vms-pcap.zip
$ rename [.simh-vms-pcap]pcap-vms.dir []
The PCAP-VMS components are presumed (by the descript.mms file) to be located in a directory at the same level as the directory containing the simh source files. For example, if these exist here:
[]descrip.mms []scp.c etc.
Then the following should exist: [-.PCAP-VMS]BUILD_ALL.COM [-.PCAP-VMS.PCAP-VCI] [-.PCAP-VMS.PCAPVCM] etc.
To build simulators:
On a VAX use:
$ MMx
On a Alpha & IA64 hosts use:
$ MMx ! With Ethernet support
$ MMx/MACRO=(NONETWORK=1) ! Without Ethernet support
UNZIP can be found on the VMS freeware CDs, or from www.info-zip.org MMS (Module Management System) can be licensed from HP/Compaq/Digital as part of the VMS Hobbyist program (it is a component of the DECSET product). MMK can be found on the VMS freeware CDs, or from http://www.kednos.com/kednos/Open_Source/MMK DEC C can be licensed from HP/Compaq/Digital as part of the VMS Hobbyist program.
If you find problems or have suggestions relating to any simulator or the simh package as a whole, please report these using the github "Issue" interface at https://github.com/simh/simh/issues.
Problem reports should contain;
- a description of the problem
- the simulator you experience the problem with
- your host platform (and OS version)
- how you built the simulator or that you're using prebuilt binaries
- the simulator build description should include the output produced by while building the simulator
- the output of SHOW VERSION while running the simulator which is having an issue
- the simulator configuration file (or commands) which were used when the problem occurred.