Re: [stella] Re: PCAE and Pitfall 2

Subject: Re: [stella] Re: PCAE and Pitfall 2
From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx>
Date: Wed, 6 Mar 2002 16:11:43 +0100
> How does the 2k fit with the areas x1000-x107F and x1800-x187F ?  Where
> are the random number generators used?  I get lost as I follow the PCAE
> source down into x86 assembly land...
> Any clues?

The 2K of extra ROM contain some graphics data. Through the ports
at the specified address range you can set some pointers into this
data, which do auto-decrements and bounds checking on each new
read from the pointer address. Also the DPC chip can produce samples
for a three-voice squarewave tune.

David Crane did file a patent for the DPC chip. A PDF version of
this document can be downloaded from the patent office, I think.
It contains detailed explanations of all the functions and
addresses. I forgot the URL, but it has been mentioned in this
list before, so searching in the stella-list archives might
get you in the right direction.

Ciao, Eckhard Stolberg

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