Re: Disassembly of the Z80 ROM of the C128

From: David Wood <*jbevren_at_gmail.com*> Date: Sat, 25 Feb 2017 10:00:43 -0500 Message-ID: <CAAuJwirKNZoVvh3+pb8a8WNiOsyEZ3B8dUvYwZto7DJALwekyA@mail.gmail.com> · jbevren_at_gmail.com

Zimmers does have the 4k z80 bios as a separate image in the firmware
directory.

I thought the z80 source was in the wild, but I guess I'm mistaken.
Perhaps it's hiding on one of thte cp/m disks?

At any rate, the z80 bios is here:
http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/c128/z80bios.bin

On Sat, Feb 25, 2017 at 8:38 AM, Marko Mäkelä <msmakela@gmail.com> wrote:

> On Sat, Feb 25, 2017 at 12:58:06PM +0100, Ruud@Baltissen.org wrote:
>
>> Is there a disassmbly of the Z80 ROM of the C128, used to boot CP/M,
>> available?
>>
>
> Actually the whole C128 boots up with the Z80. If I remember correctly,
> the Z80 is checking the C= key and the -GAME and -EXROM inputs of the MMU,
> deciding whether to switch to the C64 mode. Another (redundant) check is
> done by the 8502. I happen to know this, because I made some minor tweak to
> my C128 startup. I cannot remember what that tweak was, but I guess that I
> could dump the ROM to find out.
>
>         Marko
>
>
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>

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