Emulators

[Warren Toomey]

In article by emanuel stiebler:
> Hi,
> Anybody here, who made some benchmarks of the different simulators (supnik,
> apout, ...)
> 
> What I'm looking for is something like:
> supnik version xxx on pentium 2 350 MHz using linux, is xxx times faster
> than a 11/73.
> 
> cheers & thanks,
> emanuel

Here's my no-numbers-just-gut-feelings of the various PDP-11 emulators.
John Wilson's Ersatz is probably the fastest; it's written in assembly
code, and so gains a fair bit that way.

Second would be the Begemot emulator. They've unrolled the instruction
decode loop heavily, and that helps a lot.

Bob Supnik's emulator would be the slowest of the three. However, it's
still not that slow, may 1/3 the speed of Ersatz.

Apout can't be compared to the above 3 emulators, because it doesn't emulate
peripherals nor supervisor mode. User-mode instructions run at about the
same speed as Supnik's emulator, but system calls are done by native code.

The sole benchmark I have is: FreeBSD identifies my desktop box as
Pentium II/Xeon/Celeron (348.93-MHz 686-class CPU). Using Apout, I can
compile the 2.11BSD GENERIC kernel in 4 minutes 15 seconds.

I'll try building Supnik and Begemot and getting comparative results.

Last comment: all the simulators have strengths & shortcomings, and that
applies not just to ease of use but also to CPU, I/O performance etc. You
really have to try them all & find the one that suits you.

	Warren

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