SIMH/Draft
SIMH consists of simulators for a lot of different machines, and as such, is a very important emulator for anyone interested in computer history; in particular, that of DEC systems, as the PDPs and even some VAX models are well emulated by it.
It can even emulate network interfaces for some of the simulated computers, e.g. the PDP-10, PDP-11 and VAX, so the emulated systems can network directly onto the Internet, if the emulated operating system supports it, like BSD or VMS.
SIMH was primarily written by Bob Supnik of Zork porting fame, and is now widely contributed to by others as well.
SIMH Flavors
For some time passed there are three flavors of SIMH now:
- "Classic" SIMH (http://simh.trailing-edge.com/)
- "New" SIMH (https://github.com/simh/simh)
- OpenSIMH (https://opensimh.org/)
It is relatively hard for a beginner to decide which way to go. I will not give any specific advice, but some short descriptions:
"Classic" SIMH is the oldest one, whereof the others were forked later on. It is Bob Supnik work mostly, except for some HP simulators. Development apparently stopped (or at least slowed down) in December 2022. The current version is SIMH V3.12-3.
"New" SIMH was the first bigger fork and added a lot more simulated computer systems.
"OpenSIMH" forked from "New" SIMH because of insurmountable different opinions of both maintainers and contributors.
Usage
SIMH can either take in configuration parameters interactively, or you can store them in a file. If the file is the name of the emulator+.ini it will load them automatically (eg vax.exe loads vax.ini automatically). Once running, the CONTROL+E key will break the emulation and bring you back to the SIMH console where you can alter the running state.
Networking is covered in the Networking with SIMH guide.
