Re: SFD 1001, C128, ...

From: Andre Fachat (
Date: 1998-02-09 11:47:26

Marko Mäkelä wrote:
> ---------- Forwarded message ----------
> Date: Thu, 5 Feb 1998 23:16:10
> From: "William M. Levak" <>
> To: Marko Mäkelä <>
> Subject: Re: several messages
> The last 2K of the PET character files did not look like reversed
> characters.  They looked like fill characters, mostly FF, as if he read
> the 2K ROM as a 4K ROM.

The PET charom is only 2k in size. The inversion is done by directly
taking the 8th data bit (with value 128) of the character index
and inverting the video signal with that - saves you a then precious
2k of (EP)ROM space. This design is kept at least until the 8296.

Marko, I have a non-complete, hand-drawn schematic of a 8296 board.
I "beeped" it directly, following the connections on the board.
After I had the major parts of the board I stopped.
So it is not complete and surely contains bugs.

Interested? I could probably scan them and send by email.
(Ruud, do you still want to draw them in you program?)


Email address may be invalid. Use "fachat AT physik DOT tu-chemnitz DOT de"
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Andre Fachat, Institute of physics, Technische Universität Chemnitz, FRG

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