{"id":13241,"date":"2025-10-08T00:27:33","date_gmt":"2025-10-08T00:27:33","guid":{"rendered":"https:\/\/avitech.com.au\/?page_id=13241"},"modified":"2025-10-08T08:46:46","modified_gmt":"2025-10-08T08:46:46","slug":"open-simh","status":"publish","type":"page","link":"https:\/\/avitech.com.au\/?page_id=13241","title":{"rendered":"Open-SIMH"},"content":{"rendered":"<p>This page has my notes relating to building and using Open-SIMH, particularly in the context of Windows machines.<\/p>\n<p>The website for Open-SIMH is here -> <a href=\"https:\/\/opensimh.org\/\" .target=\"_blank\">https:\/\/opensimh.org\/<\/a><\/p>\n<p>The official Open-SIMH repository can be found here -> <a href=\"https:\/\/github.com\/open-simh\/simh\" target=\"_blank\">https:\/\/github.com\/open-simh\/simh<\/a><\/p>\n<p>That official Open-SIMH repository has source code only.  It does not contain any Windows executables.<\/p>\n<h4>Pre-built Open-SIMH executables<\/h4>\n<p>Downloading and compiling the Open-SIMH emulators on a Linux machine is fairly simple.  Windows is not so straight forward.<\/p>\n<p>Thankfully, Terri Kennedy has created a repo with pre-built executables for Windows (as well as other platforms).<\/p>\n<p>Terri&#8217;s repo is available here -> <a href=\"https:\/\/github.com\/Terri-Kennedy\/Open-SIMH-Unofficial-Builds\" target=\"_blank\">https:\/\/github.com\/Terri-Kennedy\/Open-SIMH-Unofficial-Builds<\/a><\/p>\n<p>Here is a local copy of the Windows builds from Terri&#8217;s repo as at 08-OCT-2025 (based on Open-SIMH GitHub commit 6e9324e09f4f364346310de34849077c986c29f2&#8243;) for the Altair, AltairZ80, pdp8 and pdp11 emulators, together with Terri&#8217;s notes (including the Windows build process) -> <a href=\"https:\/\/www.avitech.com.au\/mm-files\/open-simh-windows-builds\/open-simh-windows-builds-2025-oct-08.zip\">Windows Open-SIMH Builds as at 08-OCT-2025<\/a>.<\/p>\n<h4>Building Windows executables using Cygwin<\/h4>\n<p>Before Terri&#8217;s pre-built executables became available, I experimented with making my own builds using Cygwin.<\/p>\n<p>Here&#8217;s the process I followed to build a Windows executable version of an Open-SIMH emulator under Windows 11 Pro:<\/p>\n<ul>\n<li>Download and install cygwin.  Just go with the defaults except add make, cmake, gcc and vim<\/li>\n<li>download the open-simh package and unzip it on your PC. I chose to put the files at C:\\open-simh-simh-29d3900<\/li>\n<li>Run cygwin by clicking on &#8220;Cygwin64 Terminal&#8221; in the start menu, or running &#8220;Cygwin.bat&#8221; in your cygwin64 directory. <\/li>\n<li>You can see the mounted directories in cygwin by typing the &#8220;mount&#8221; command&#8221;.  You should see that C: has been mounted as \/cygwin\/c<\/li>\n<li>In cygwin, change from your cygwin home directory into the open-simh directory (for me that was done using the command &#8220;cd  \/cygdrive\/c\/open-simh-simh-29d3900&#8221;). Check that you can see the SIMH files there using the &#8220;ls -l&#8221; command<\/li>\n<li>Build the PDP-8 simulator using the command &#8220;make pdp8&#8221;.  This will take a minute or so.  The resultant windows executable will be located in the BIN directory under your open-simh directory<\/li>\n<li>You can now execute the pdp8 simulator in the cygwin environment using the &#8220;.\/pdp8&#8221; command<\/li>\n<li>Exit cygwin using the &#8220;exit&#8221; command<\/li>\n<p>You will also now be able to execute the PDP-8 windows executable in the native Windows environment, provided you have edited your PATH environment to add the cygwin64\\bin directory (so Windows finds the &#8220;cygwin1.dll&#8221; file when you run &#8220;pdp8.exe&#8221;). To do this I went into &#8220;Settings&#8221; from the start button, then searched for &#8220;environment variables&#8221; in the &#8220;Find a setting&#8221; search bar and selected the result &#8220;Edit the system environment variables&#8221;<\/li>\n<\/ul>\n<p>The above example is to build the pdp8 simulator on (and to run under) Windows 11 Pro.<\/p>\n<p>I also used the same Cygwin environment to assemble palbart from David&#8217;s site.  It can be found here -> <a href=\"https:\/\/www.pdp8online.com\/ftp\/software\/palbart\/\" target=\"_blank\">https:\/\/www.pdp8online.com\/ftp\/software\/palbart\/<\/a>.  It assembles under Cygwin with the command &#8220;gcc -o palbart palbart.c&#8221;.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>This page has my notes relating to building and using Open-SIMH, particularly in the context of Windows machines. The website for Open-SIMH is here -> https:\/\/opensimh.org\/ The official Open-SIMH repository can be found here -> https:\/\/github.com\/open-simh\/simh That official Open-SIMH repository has source code only. It does not contain any Windows executables. Pre-built Open-SIMH executables Downloading ..<\/p>\n<div class=\"clear-fix\"><\/div>\n<p><a href=\"https:\/\/avitech.com.au\/?page_id=13241\" title=\"read more...\">Read more<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-13241","page","type-page","status-publish","hentry"],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/P7xTsk-3rz","jetpack-related-posts":[{"id":2514,"url":"https:\/\/avitech.com.au\/?page_id=2514","url_meta":{"origin":13241,"position":0},"title":"SerialDisk Integration to SIMH","author":"malcolm","date":"20-August-2017","format":false,"excerpt":"This page describes the process of setting up an interface between SIMH and SerialDisk, so that SIMH has read\/write access to the same image files as SerialDisk serves up to a real PDP-8. Most of what you need to do this is already set up in Kyle's distribution of SerialDisk.\u2026","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":709,"url":"https:\/\/avitech.com.au\/?page_id=709","url_meta":{"origin":13241,"position":1},"title":"PDP-11 Paper Tape BASIC","author":"malcolm","date":"3-July-2016","format":false,"excerpt":"Introduction This page provides an overview of PDP-11 paper tape BASIC, and the computer equipment it was typically used with. It then describes how to load and run PDP-11 BASIC on real PDP-11 hardware, and how it can be run instead on a modern Windows-based PC, under the open-source SIMH\u2026","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"DEC-11-AJPB-PB","src":"https:\/\/i0.wp.com\/avitech.com.au\/wp-content\/uploads\/2016\/07\/DEC-11-AJPB-PB-300x44.jpg?resize=350%2C200","width":350,"height":200},"classes":[]},{"id":2735,"url":"https:\/\/avitech.com.au\/?page_id=2735","url_meta":{"origin":13241,"position":2},"title":"SCSI2SD on QBUS PDP-11","author":"malcolm","date":"15-October-2017","format":false,"excerpt":"Until recently I was using an MFM hard drive as the primary hard drive on my QBUS PDP-11 systems. Typically this would be an RD31 (ST-225) on an RQDX3 MSCP controller. Over time, I am converting to using an 8GB microSDHC card as the primary hard drive. This is achieved\u2026","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":2634,"url":"https:\/\/avitech.com.au\/?page_id=2634","url_meta":{"origin":13241,"position":3},"title":"DEC PDP-11\/73 in BA123 cabinet","author":"malcolm","date":"30-September-2017","format":false,"excerpt":"I have built up a PDP-11\/73 system in a BA123 cabinet. My aim is for this system to be able to boot either RT-11 V5.7 or RSX-11M+. The primary MSCP controller is a CMD CQD-220 controller with a SCSI2SD device connected to it. Up to 4 logical devices can exist\u2026","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":12693,"url":"https:\/\/avitech.com.au\/?page_id=12693","url_meta":{"origin":13241,"position":4},"title":"PDP-8 notes: Dumprest and paper-tape diagnostics","author":"malcolm","date":"29-June-2025","format":false,"excerpt":"These are my rough notes about using paper-tape diagnostics and dumprest on the PDP-8. This page focuses in particular on using dumprest on a Windows machine in a Cygwin environment. I have a separate page here that provides some tips for setting up Cygwin. Dumprest Dumprest is a series of\u2026","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1964,"url":"https:\/\/avitech.com.au\/?page_id=1964","url_meta":{"origin":13241,"position":5},"title":"DEC VT340 Internals","author":"malcolm","date":"26-April-2017","format":false,"excerpt":"In early 2017 there was some discussion on the SIMH mailing list regarding the simulation of various DEC VT-series terminals. Part of that discussion related to the ROMs and architecture inside DEC's VT340 terminal. According to that discussion the firmware for the VT340 includes the following: 512 x 8 2804\u2026","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/avitech.com.au\/wp-content\/uploads\/2017\/04\/20170418_224430_1492519519228_resized-e1492520859459.jpg?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/avitech.com.au\/wp-content\/uploads\/2017\/04\/20170418_224430_1492519519228_resized-e1492520859459.jpg?resize=350%2C200 1x, https:\/\/i0.wp.com\/avitech.com.au\/wp-content\/uploads\/2017\/04\/20170418_224430_1492519519228_resized-e1492520859459.jpg?resize=525%2C300 1.5x, https:\/\/i0.wp.com\/avitech.com.au\/wp-content\/uploads\/2017\/04\/20170418_224430_1492519519228_resized-e1492520859459.jpg?resize=700%2C400 2x, https:\/\/i0.wp.com\/avitech.com.au\/wp-content\/uploads\/2017\/04\/20170418_224430_1492519519228_resized-e1492520859459.jpg?resize=1050%2C600 3x, https:\/\/i0.wp.com\/avitech.com.au\/wp-content\/uploads\/2017\/04\/20170418_224430_1492519519228_resized-e1492520859459.jpg?resize=1400%2C800 4x"},"classes":[]}],"_links":{"self":[{"href":"https:\/\/avitech.com.au\/index.php?rest_route=\/wp\/v2\/pages\/13241","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/avitech.com.au\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/avitech.com.au\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/avitech.com.au\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/avitech.com.au\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=13241"}],"version-history":[{"count":10,"href":"https:\/\/avitech.com.au\/index.php?rest_route=\/wp\/v2\/pages\/13241\/revisions"}],"predecessor-version":[{"id":13254,"href":"https:\/\/avitech.com.au\/index.php?rest_route=\/wp\/v2\/pages\/13241\/revisions\/13254"}],"wp:attachment":[{"href":"https:\/\/avitech.com.au\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13241"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}