Re: PET 8032 editor ROM

From: Andre Fachat (
Date: 1998-02-23 12:35:50

Marko Mäkelä wrote:
> ROM is causing some trouble.  I saved VICE's version as
> /pub/cbm/firmware/computers/business/pet/edit-4-80-b-50Hz.901474-04?.bin,
> because it only has 12 different bytes from the 901474-04 ROM image
> that was already on FUNET.  All differences are after $e720, right
> after the dL"*^Mrun^M thing.  Does anyone know what the bytes are used
> for?  For the CRTC initialization perhaps?

I have found it now: at $e07a a vector $e72a is loaded to $c7/$c8
(at $e082 the vector is $e73c), which is used as index. 
Then the 18 bytes following this address are stored to the registers 
0-17 into the VDC.
Those values directly after the dL"*".. thing should be 
register values for the VDC then.


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Andre Fachat, Institute of physics, Technische Universität Chemnitz, FRG

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