[sebhc] Dave Dunfield's H8 emulator

[Dave Dunfield]

At 22:01 12/05/2004 -0500, you wrote:
>Not even RTFM - just RTFScreen - setting the PC to 040.100 works just
>fine on my windows machines (2K and XP); just barely loads on my
>386SX/16.

So does this mean you got it to work?

I'd still like to follow up the "crash and burn" problem that you were
having at 040.000.

Btw, an SX16 should work, but it's getting on the low range for the
emulator - There are two speed issues:


A) The constant H8 interrupt takes a fair bit of work to simulate, and
   the # instructions/sec seems to go down exponentially as the PC clock
   slows.

B) The emulator requires a calibration to emulate this interrupt correctly
   - It has an ongoing "correction" which gets applied to account for drift
   in the operating environment, but it does not currently perform a calibration
   at startup - I have been assuming a relatively fast machine.
   It will probably work OK if you leave it sit long enough!
   My 386/33 took a few seconds to get synced, then everything was OK - it
   executes about 260,000 virtual 8080 instruction/second (on contrast to
   about 20mips on my P3/733).
   Once I add a startup calibration it should work much better on slower
   machines.

Regards,
Dave
-- 
dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Vintage computing equipment collector.
                http://www.parse.com/~ddunfield/museum/index.html

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