Re: (Fwd) Re: 8032 crt vs. 3032 crt

From: MikeS <dm561_at_torfree.net>
Date: Tue, 2 Jul 2013 02:28:30 -0500
Message-ID: <66838E501DE4454CA1732F7E9D2C3AF9@vl420mt>
----- Original Message ----- 
From: "A. Fachat" <afachat@gmx.de>
To: <cbm-hackers@musoftware.de>
Sent: Tuesday, July 02, 2013 1:05 AM
Subject: Re: (Fwd) Re: 8032 crt vs. 3032 crt


> Am 2. Juli 2013 08:46:15 schrieb "MikeS" <dm561@torfree.net>:
>> It turns out that there is a routine in the graphic ROM that checks for
>> presence of the VIDEO ON signal on PB5 of the VIA that is not in the
>> business version; the problem was a broken trace from the PIA to the VIA.
>
> Ah,  a remnant of the old PET 2001 "don't access the screen memory while
> displaying" code - that waited for retrace before printing to avoid snow
> on the screen.
> This code is also the cause for the speed up poke that turned into a
> killer poke.
>
> Didn't think it was still in the Basic4 editor.
>
> Andr
-----------------
You're right again; it isn't. I forgot to mention that the BASIC4 graphic
ROM started to work for some reason, perhaps a bad socket; it was only the
BASIC2 graphic ROM that was still hanging up waiting for that signal.

m


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Received on 2013-07-02 07:01:33

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