[sebhc] H8 Emulator update

Steven Parker sp11 at hotmail.com
Sun May 30 18:37:50 CDT 2004

Dave says:
> >Why not provide HDOS 2.0 instead?
>Two reasons: 1) ...the disks are big I don't want to have to include too
>many of them.

Since you zip your package, I think they shrink down pretty well.  A user 
might appreciate a complete 2.0 disk set.  OR .. just include a reference to 
SEBHC, so they can get support here!

> >It would be nice to have a "real 8080" mode ....
>Not currently - it's doable, but why are you so concerned about invalid
>opcodes? - I won't think this should be an issue (except of course for the
>HASL thing - which is a NOP in disguise). Did Heath use the other undoced

I'm sure Heath never used any deliberately - the HASL thing is surely a case 
where an address was pointing to the wrong place and it was never discovered 
because in testing (on real hardware) it worked as intended.

My interest would be to have a completely precise emulation of the cpu 
functionality.  Not only to cover any other possible software accidents like 
HASL, but also to cover cases where programmers intentially did little 
"tricks" to determine if the processor is an 8080 or Z80, or perhaps to 
impede reverse-engineering of their code.  Plus I just kinda like the idea 
of knowing the emulator is going to respond EXACTLY like the real thing.  

Jack says:
>Another "problem" is with the low level commands INIT and SYSGEN - if I
>try to run INIT, it exits gracefully with the error message "Wrong type
>of media ...". I can ctrl-D out of it and reboot, but I can't initialize
>a disk. Likewise with SYSGEN - if I attempt to gen a disk, I get an
>error saying the disk is not initialized by the correct version of INIT

I was able to sysgen the "empty.h8d" that I added to disk-images/other.  
It's an HDOS 2.0-style initted disk image and I was using HDOS 2.0 sysgen.   
I did get a funny message about an illegal .DVD filename during the sysgen 
(will have to try this on a real H8 when I find my spare disks) but the disk 
image it made "boots" just fine.


- Steven

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