Re: VC-20 all 16 colours full-screen?

From: Francesco Messineo <francesco.messineo_at_gmail.com>
Date: Thu, 2 Sep 2021 14:08:18 +0200
Message-ID: <CAESs-_w91Rqpacoptr8d5m=Q-d-K1aKz8yZk85Vt1fuhp-Bntw_at_mail.gmail.com>
On Thu, Sep 2, 2021 at 1:27 PM Gerrit Heitsch <gerrit_at_laosinh.s.bawue.de> wrote:
>

> > Now time to get a working VC-20. What's the most common "black screen" suspect on the VIC?
>
> Besides VIC itself? The ROMs and if they are present, the 65245 bus
> buffers. The latter can be replaced by 74LS245.
>
> But I also had bad RAM, a bad LM323 voltage regulator and a bad 74LS138.

I can add also (from real repairs): 6502 (very rarely, but happens),
the 7402 on the clock generator, a 6522 jamming the databus.
>
> So dust off your scope and go hunting.

that's the only good way.

Frank IZ8DWF
Received on 2021-09-02 15:00:02

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