# SIMH emulator

13 Hacker News commenters recommended SIMH emulator and 1 criticized it, November 2025 to November 2026. It was recommended in 8 of 13 months. It meets the Hacker Approved badge rule.

**Verdict:** 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.

## Why people recommend it

- Runs many historic DEC systems (3 comments): "SIMH emulates the PDP-11 (along with a ton of other early mini/microcomputers)." ([source](https://news.ycombinator.com/item?id=45858292)) "SIMH (for old DEC computers): NetBSD, VMS, Ultrix, RSX-11M, RT-11" ([source](https://news.ycombinator.com/item?id=47837190)) "You can emulate ITS for the PDP10 today under simh-classic" ([source](https://news.ycombinator.com/item?id=45864490))
- Good speed for emulated systems (2 comments): "runs the SIMH VAX emulator with 64MB for the VAX at the same speed as a Vaxstation 4000/60" ([source](https://news.ycombinator.com/item?id=47999480)) "for sure it runs at decent speeds, almost like an emulated Pentium 90" ([source](https://news.ycombinator.com/item?id=47158279))
- Works well with Termux (2 comments): "I've got a VAX/VMS 11/780 that I can run inside it thanks to SimH and Termux" ([source](https://news.ycombinator.com/item?id=46211988)) "I love OpenSimH and Termux." ([source](https://news.ycombinator.com/item?id=48800028))

## What people warn about

- Accuracy not yet verified (1 comments): "What is missing for a SIMH simulator is original software to make sure the simulator is accurate (currently it is not)." ([source](https://news.ycombinator.com/item?id=49487522))
- Setup needs patience and learning (1 comments): "it's not super hard to set up, just takes a bit of patience and willingness to learn how opensimh works" ([source](https://news.ycombinator.com/item?id=48197392))

## Alternatives hackers recommend

- [86Box](https://hackerapproved.com/p/86box.md): 25 recommend
- [Infinite Mac](https://hackerapproved.com/p/infinite-mac.md): 11 recommend
- [Executor](https://hackerapproved.com/p/executor.md): 9 recommend
- [WinUAE](https://hackerapproved.com/p/winuae.md): 6 recommend
- [Basilisk II](https://hackerapproved.com/p/basilisk-ii.md): 5 recommend

## Cite as

Hacker Approved, "SIMH emulator", https://hackerapproved.com/p/simh/ (counts from 1,795,640 Hacker News comments, November 2025 to November 2026).