[sebhc] Dave Dunfield's H8 emulator

Jack Rubin jack.rubin at ameritech.net
Thu May 13 07:27:13 CDT 2004

> This is "normal" on a slow machine - it will (well - should) 
> eventually sort itself out, but it takes a LONG time on a 
> machine less than 386/33
> - if you want closely, you will (after while) see the display 
> segments start to update - one at a time.
> This is because the emulator is inserting virtual interrupts 
> between intervals of 8080 instructions, and on a slow machine 
> they are inserted very infrequently - the VM self-adjusts to 
> bring them to a 500hz rate, however this adjustment is very 
> slow, so that it does not get fooled by momentary changes in 
> system performance (interrupts, multitasking etc.)
> - It's more of a "slow drift".
> Basically what is happening is that the H8 turns on the 
> buzzer, and is now waiting for a timeout - on a slow machine, 
> the interrupts are happening so infrequently that this takes 
> a LONG time.

yeah - I've been thinking about upgrading to a 386DX/33 - this may be
the killer app that pushes me over the edge!


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