SIMH emulator
Hacker ApprovedRanked 7 of 20 emulators by recommenders
Free emulator for old DEC and other early minicomputers, able to run systems like VAX/VMS, Unix and RSX-11 on modern machines. Setup takes patience, and people note that accuracy is not yet fully verified.
Free emulator for old DEC and other early minicomputers, able to run systems like VAX/VMS, Unix and RSX-11 on modern machines. Setup takes patience, and people note that accuracy is not yet fully verified.
14 people gave an opinion
- recommend it
- 13
- criticize it
- 1
- approval share
- 93%
Recommended in 8 of 13 months
- November 2025: recommended
- December 2025: recommended
- January 2026: not recommended
- February 2026: recommended
- March 2026: recommended
- April 2026: recommended
- May 2026: recommended
- June 2026: not recommended
- July 2026: recommended
- August 2026: not recommended
- September 2026: not recommended
- October 2026: recommended
- November 2026: not recommended (month in progress)
Why it carries the badge
- 13 people recommend itNeeds 10 or more, met.
- 13 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 8 of 13 monthsNeeds 4 or more, met.
The same three rules apply to every product, and the badge can’t be bought. How the badge works
What people say about it
The reasons people give, with the number of comments that give each one. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Runs many historic DEC systems
“SIMH emulates the PDP-11 (along with a ton of other early mini/microcomputers).”
Comment from 8 Nov 2025 in “52 Year old data tape could contain Unix history” “SIMH (for old DEC computers): NetBSD, VMS, Ultrix, RSX-11M, RT-11”
Comment from 20 Apr 2026 in “SDF Public Access Unix System” “You can emulate ITS for the PDP10 today under simh-classic”
Comment from 9 Nov 2025 in “52 Year old data tape could contain Unix history” Good speed for emulated systems
“runs the SIMH VAX emulator with 64MB for the VAX at the same speed as a Vaxstation 4000/60”
Comment from 3 May 2026 in “Embedded Rust or C Firmware? Lessons from an Industrial Microcontroller Use Case” “for sure it runs at decent speeds, almost like an emulated Pentium 90”
Comment from 25 Feb 2026 in “Debian Removes Free Pascal Compiler / Lazarus IDE” Works well with Termux
“I've got a VAX/VMS 11/780 that I can run inside it thanks to SimH and Termux”
Comment from 9 Dec 2025 in “Ask HN: Are there any viable Android phones for a power user to buy nowadays?” “I love OpenSimH and Termux.”
Comment from 6 Jul 2026 in “Run Windows 2000 on a DEC Alpha with a new es40 fork”
What people warn about
Each mark is one comment
Accuracy not yet verified
“What is missing for a SIMH simulator is original software to make sure the simulator is accurate (currently it is not).”
Comment from 29 Aug 2026 in “French CII's Mitra-15 in SIMH. Work in Progress” Setup needs patience and learning
“it's not super hard to set up, just takes a bit of patience and willingness to learn how opensimh works”
Comment from 19 May 2026 in “I've built a virtual museum with nearly every operating system you can think of”
Other emulators people recommend
The four most recommended other emulators, with the same counts for each, so you can compare like for like. The tick on each bar marks the 2 to 1 line the badge needs.
See all 20 emulators, rankedWhat people said
18 of the 22 comments that mention it, newest first. Each links to the original comment.
“What is missing for a SIMH simulator is original software to make sure the simulator is accurate (currently it is not).”
“I love OpenSimH and Termux.”
“it's not super hard to set up, just takes a bit of patience and willingness to learn how opensimh works”
“runs the SIMH VAX emulator with 64MB for the VAX at the same speed as a Vaxstation 4000/60”
“looks like a good place to start”
“I can telnet in to the virtual VAX from my other PCs.”
“SIMH (for old DEC computers): NetBSD, VMS, Ultrix, RSX-11M, RT-11”
“If you want to relive it then simh with mame might be an option.”
“for sure it runs at decent speeds, almost like an emulated Pentium 90”
“+1 for using SGI hardware to run the PDP-11 emulator”
“I've got a VAX/VMS 11/780 that I can run inside it thanks to SimH and Termux”
“simh deserves the credit here”
“You can emulate ITS for the PDP10 today under simh-classic”
“Today simh-classic it's serious stuff up to the point a fork was made”
“Simh will run it for sure”
“Given who wrote it, simh seems as close to an official VAX emulator as you are going to get.”
“SIMH emulates the PDP-11 (along with a ton of other early mini/microcomputers).”
“now I prefer simh-classic”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.