[sebhc] Emulator evolution

Steven Parker sp11 at hotmail.com
Tue May 25 11:33:46 CDT 2004

>I have identified the problem - the HDOS 2 driver in high memory uses a 
>timeout based on the CPU speed while looking for sector holes

How rude!  :-)   This appears to be a new function Greg added when creating 
the modular driver (the modular drivers are being loaded at that point in 
the boot - thus the console re-init also).  I wonder if another fix for this 
would be to just change SY.DVD.  I see in the source where the routine 
"SYREDY" is checking for a full rotation (12 holes) to occur in a specific 
time.  It would be easy to make it clock-based instead of count-based.  
Another cool driver mod would be to lower the step time minimum to 0 and 
make motor delay also settable to 0.

>So - looks like I will have to implement the auto-calibration function to
>set the CPU speed when the emulator starts.

Darn.  It's nice having an extra-fast H8.   :-)  Maybe that could be 
switchable, so you could turn on "max speed" after boot, or start up that 
way if your disk image has the new driver?

>Whats 'PAM8GO' is his a PAM8 modified to automatically boot?

Not quite.  It's a one-button boot.  The only difference between PAM8 and 
PAM8GO is that after reset, the latter presets the value of PC to 030.000.  
So just hitting the "go" button (thus the name) causes it to boot.  Actual 
autoboot was first available on the HA-8-6 (Z80) cpu as a switch-selectable 

>I'm not real keen to replace the ROM image, because that would make it 
>from my real H8

You could burn one for your H8.  :-)

>It may not be obvious, but the L= command line option can load code/data
>anywhere, even in ROM space.

That works too!

I wonder if you'd be willing to do one thing in your emulator that would 
diverge from reality?  Add a stub so that a device driver could get access 
to files in a specific folder on the PC.  This would effectively create a 
virtual HD on the PC.  What do you think?  :-)


- Steven

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