[Coco] Still having newbie issues

Darren A mechacoco at gmail.com
Wed Jul 9 20:42:16 EDT 2014

On Wed, Jul 9, 2014 at 6:22 PM, Stephen Pereira wrote:

> Hi Darren,
> Thank you very much for your response.  I greatly appreciate it.
> Do you have any idea why Zork II and Zork III start up fine on my physical
> system with HDB-DOS but Zork i will not?  I hear you that Zork used its own
> code to access the disk, but don't you think that would also be the case
> for Zork II and Zork III also?
> i don't really care if I cannot save a game because of the special disk
> access code, but why can Zork I start up and work on my VCC emulator, but
> it won't even start up on my physical system?

All I can say for sure is that I recently tested Zork I and found that it
was executing its own disk IO routines located somewhere in the $5xxx area
of RAM, definitely not from ROM.

Maybe they changed their code to use the ROM driver in the later versions
or maybe someone has patched those disk images to get around the problem.

It works in the emulators because VCC and MESS both emulate the floppy
hardware whereas HDB-DOS is just a software patch of the Disk Basic ROM
driver. If a program does not call the ROM driver than HDB-DOS/DW has no
chance to intervene.


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