Re: Broken P500

From: Michał Pleban <*lists_at_michau.name*> Date: Tue, 02 Oct 2012 21:36:24 +0200 Message-ID: <506B4238.9020306@michau.name> · lists_at_michau.name

Hello!

Rob Clarke wrote:

> WRT to the 6525, a bad one can 'black screen' the system. The one that
> handles the keyboard also controls the 16k bank that the vic-ii sees.
> When I got that batch of 6525's a few months ago I did not have a
> socketed 6525 in any of my cbm-ii machines to test with but I now have a
> P500 with a socketed 6525 and I know that some of the bad ones will stop
> the machine from visibly booting.

OK, that's indeed a valid theory. But I recall from previous
conversations from Steve that the activity on the address lines was
somewhat different from a working one, which a bad 6525 would not produce.

But this should be rather simple to check? One could just check the
voltage on these A14 and A15 pins coming out of the TPI?

Regards,
Michau.

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