Re: commodore 8032 vga / ports to monitor

From: Rhialto <rhialto_at_falu.nl>
Date: Sun, 25 Feb 2018 23:48:33 +0100
Message-ID: <C96D644C-C881-4D14-BEF0-DD78A26D0FEC@falu.nl>
On 25 February 2018 00:28:53 CET, Mia 
>There is the "killer poke" that turns the VSYNC detect input to an
>output. On the oldest PETs the hardware did drive hard enough that this
>didn't matter but it disabled the timing logic halting the cpu when
>accessing video ram while video were displayed. On newer machines it
>messes up VSYNC output.

There was a loop in ROM that tested the bit and delayed until retrace. It was taken out later.


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Received on 2018-02-26 00:02:27

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