32 bit virtual computers remade with

When timesharing was a new thing, people tended to create software for virtual machines of all sizes.Are there any simple Virtual designs for 32 bits that could easly implimented with a 2901 cpu? After the IBM PC, I suspect all this stuff was mostly forgotten, lost from the public eyes.

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In 2015 Long Tien Nguyen and Alan Kay proposed a simple 32 bit virtual machine called “Chifir” in their paper “The Cuneiform Tablets of 2015”. The idea is to store executable versions of historical software systems to that future archeologists can just implement the simple VM in whatever computer they have and then experience the saved software.

The instruction set is not very compact - each instruction takes four 32 bit words even though several instructions need less than three arguments and there are fewer than 16 instructions (so a 32 bit opcode is absurdly wasteful).


I like the idea of something simple and regular, even if it loses some efficiency.

I was thinking more like BCPL and SKIMP virtual machines. The biggest problem if i read it right,
with “Chifir” is you have no indexing feature.
Bens 32 bit cpu

Do you have a reference for SKIMP? I can’t find anything. I found these candidates which may or may not be the kind of thing you’re thinking of:

I picked that list out from here. This page didn’t seem very fruitful.

I’m not sure if various Lisp and Scheme bytecodes are targeting something recognisable as a virtual machine in the sense you’re looking for.

Actually this page has appropriate information including about SNOBOL and TinyBasic:

Skimp I found here.

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Ah thanks, a skinny IMP, circa 1979, with a 32-bit virtual target.

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Three commercial computers that were specifically designed to run virtual machines:

  • IBM 5100 (16 bits to emulate the 32 bit S/360 for its APL interpreter)
  • Burroughs B1700 (24 bits to emulate virtual machines of any size)
  • Nanodata QM-1 (18 bits to emulate 16, 18, 32 and 36 bit virtual machines)
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Nice to see someone else remembers the QM-1! I was friends with one of their systems programmers. It was a fascinating system!

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You might be able to help with the question “What was the history of Nanodata Corporation?” on the Retrocomputing Stack Exchange.

I used IMP-77 on a 32-bit Interdata 7/32 “mini” in 78/79. the OS, Mouses, was a cut-down version of EMAS (also written in Imp) and in-use at Edinburgh University (and I think Manchester).

Nice to know that there is a cut-down version of it floating about - it might even be a candidate for a self-hosting retro style system, but there’s the need to compile the compiler …


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