recursive emulation

Pete Turnbull pete at
Tue Jan 24 10:23:46 CST 2017

On 24/01/2017 16:46, Jecel Assumpcao Jr. wrote:
> In 1988 I designed an ARM2 based computer (my Merlin 4, which was only
> built in 1992 when the ARM2 was already obsolete) and wondered if it
> could emulate a PC fast enough to be usable. I had written an ARM
> assembler and a friend did an ARM emulator running in QNX on the PC, so
> we wrote an 8088 emulator in ARM assembly. We then ran some simple 8088
> programs on the PC emulator running on the ARM emulator running on the
> PC. This allowed us to figure out that an 8 MHz ARM2 would be able to
> run PC programs at nearly the speed of a 4.77 MHz 8088.

Interesting.  You know that Acorn had a software PC emulator for the 
Archimedes called PCEmu, on sale in late 1987?  In 1988 they sold it 
bundled with an Archimedes A310 (8MHz ARM2, 1MB of RAM) called the A310M 
(M for MS-DOS).  It ran at just a little less than the speed of a 
4.77MHz 8086.  Amusingly, it ran MS-DOS better than the then-current 
Nimbus PC from their arch competitor Research Machines - PCEmu would 
happily run things like Borland Sidekick, Lotus 1-2-3, Microsoft's 
Flight Simulator etc where the RM PC often failed because it had a 
custom MS-DOS running on an 80186.

Pete Turnbull

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