[Simh] Reference performance benchmarks

[Paul Koning]

> On Dec 12, 2016, at 2:13 PM, Jacob Goense <dugo at xs4all.nl> wrote:
> 
> I'm running simh in rather tight corners. Mostly VAX/780 and PDP-11/70
> with V6 or BSD. Simh runs in a browser, or, I have (too) many of them
> on underpowered Asus Eee PC's. Any tips on how I can check if I have
> taken things too far? 

Depends on what you mean by "too far".  Do you want SIMH to run as fast as, or faster than, the real hardware?  If so, running, say, the PDP11 simulator on a 780 is probably "too far".  But it may be ok for the 1620 emulator.

If by "too far" you mean "not useable", that depends on your tolerance.  People have run PDP-11 emulators on a PDP-10 (MIMIC).  There's a document describing an Electrologica X8 emulator that runs on its predecessor the X1 -- a machine with no floating point hardware and a typical instruction time around 50 microseconds.  So the emulation runs at about 4-8 ms per emulated integer instruction, substantially slower for float.  But it was (apparently) used for initial development of substantial programs such as an ALGOL compiler.  It's all a question of what you consider reasonable.

	paul