Aw: Re: My ColourPET Project

From: André Fachat <>
Date: Fri, 12 Apr 2013 16:10:10 +0200 (CEST)
Message-ID: <trinity-0e354517-5918-4c7c-90d1-50820c6bf86f-1365775810792@3capp-gmx-bs24>
BTW, I don't know how many of you are on google+, together with Ed Spittles I have a mos6502 fan page there with weekly posts.
This week I posted about Steve's color PET this morning :-)


>Gesendet: Freitag, 12. April 2013 um 15:20 Uhr
>Von: "Steve Gray" <>
>An: "" <>
>Betreff: Re: My ColourPET Project
>The same trick commodore used to go from 40 to 80 columns would have to be used again for colour. Two bytes are read in parallel and latched. This overcomes the memory bandwidth because you are effectively doubling the bandwidth >to 16 bits. So, for 80 column colour you are doubling it again to 32 bits. Four bytes are read at the same time.
>Dual-port ram is not needed because we don't have two separate un-syncronized read or write accesses to the same memory. The cpu and the crtc do not access ram at the same time, they access on alternate clock cycles.

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Received on 2013-04-12 15:00:04

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