SIMH - multi-system simulator / News: Recent posts

vax idle

I've combined the two vax idle patches into one, and the idle still works on Win32, and now it seems to idle far better in OSX.

Posted by Jason Stevens 2010-09-03

new OSX builds

all done with 10.6.3 with i386/ x86_64 and PPC7400... hopefully this will end the madness that's been going on in the OSX world.

Posted by Jason Stevens 2010-09-02

pdp8 improved floating point

I've just added a patch for improved floating point support for the PDP8 on simh-3.8-1

Posted by Jason Stevens 2010-09-02

OS X build

I finally came across an ancient intel mac, and was able to build a standard build of SIMH on it, and did some preliminary testing, and all seemed ok.

So this is the first intel OSX binary release, sorry to the PPC users out there, this is intel only.

Posted by Jason Stevens 2010-08-05

Added VAX idle patch

from Peter Svensson. Hopefully this will address all the legacy VAX OS's on SIMH.

Posted by Jason Stevens 2010-08-03

unofficial patches for 3.8-1

I've started collecting unofficial patches for SIMH... This will make it easier for others to experiment with, and to see how SIMH can be modified for different environments...

If you have something to share, please do so, it only helps the community.

Posted by Jason Stevens 2010-04-29

SWTPc emulator added & MS-DOS build released

I have released a new version of the MS-DOS build of SIMH which includes various OS's for a few of the emulators to give a test drive to the system.

This version uses the DOS32-A extender, instead of the DOS4G/W extender, and has been tested with DOSBOX. As part of the lowest common denominator, I have included the latest build of the SWTPc 6800 emulator from the author.

Direct download link is: read more

Posted by Jason Stevens 2009-03-11

Version 3.8-1 has been released!

A new bugfix version of SIMH has been released!

Stay tuned for new binaries!

SCP and libraries:
Fixed bug in DETACH ALL if called at simulator exit (from Dave Bryan)
Fixed bug in DO command handling of null arguments (from Dave Bryan)
Fixed bug in DO handling of \\ (literal backslash) (from Dave Bryan)
Fixed warnings in help printouts
HP2100 (all changes from Dave Bryan)

Corrected DMS violation register set conditions
JSB to 0/1 with W5 out and fence = 0 erroneously causes MP abort
Fixed DJP, SJP, and UJP jump target validation
BACI: Fixed STC,C losing interrupt request on BREAK
MPX: Implemented 12792C eight-channel terminal multiplexer
MT: Fixed missing flag after CLR command
PIF: Implemented 12620A/12936A Privileged Interrupt Fences
IBM 1401: ... read more

Posted by Jason Stevens 2009-02-17

SIMH SLiRP build

I've added a build of 3.8-0 that includes the SLiRP from Qemu. The upshot is that if you are using TCP/IP, you don't need to latch onto an ethernet device, and you can telnlet back into the VM on port 42323 (it's changeable in the source). This is a boon for laptop users, or people not running with full access. I've included the full source in the zip file (in the ethernet downloads). The only special instructions for building is that the slirp directory cannot be built with -O2, as it will not function correct, and that I've only tested building this with gcc 3.4.5 with MinGW however prior versions of this worked with other OS's with GCC. I should also add, I've changed the idle code to work the prior way, and you have to boot with the cpu idle set to FIX.

Posted by Jason Stevens 2009-02-09

SimH 3.8-0 released!

Version 3.8-0 has been released!

Posted by Jason Stevens 2008-07-11

Visual C++ 2005 additions!

I've added my VC 2005 project source for 3.7-3, and included binaries with & without networking. I've also included the VC2005sp1 runtime in both exe packages (for people that get msvc8 runtime errors).

Let me ( neozeed2 at ) know about stability or speed...!

Posted by Jason Stevens 2007-09-11

First Windows Installer

I've built a windows installer package specifically for 4.2BSD. Why? Well I had all the bits lying about.

The download link can be found here:

I've seperated a 'home' disk for the user, so if they were to destroy the operating system, they can uninstall the emulator, and choose to *NOT* delete their home. Also they can overlay an install, and only install the OS.... read more

Posted by Jason Stevens 2007-09-09

SimH 3.7-3 released!

Version 3.7-3 has been released which incorporates the following bug fixes:

-Fixed bug in SET THROTTLE command

Fixed non-portable usage in SHOW HISTORY routine

TA: forward op at BOT skips initial file gap

CT: forward op at BOT skips initial file gap
-CT: fixed handling of BEOT

VAX, VAX780::
CPU: fixed bug in read access g-format indexed specifiers

Posted by Jason Stevens 2007-09-04