Adrian Vickers wrote:
> Then there's the 3016 (not 4016, as I wrote in c.s.cbm). That switches on,
> and displays a picture, but it's full of garbage.
Clear evidence of video logic which hasn't been initialized. Could be a
number of things, like a blasted ROM, faulty RAM, a broken CPU and even
the power supply.
I once got a "slim" 4032 (which is basicly the same as a 3016 with more RAM
and upgraded ROMs, no CRTC in this case) which had exactly the same symptoms
on arrival. It worked before I shipped it. It turned out that the power
supply *was* broken. The video logic is powered independantly from the
rest of the logic. It has two 7805's, one of them powering the video, the
other one the rest. (That's not entirely true, but it does boil down to
that). In my case, the lower 7805 had died, the upper one still worked,
giving exactly the things you described.
I'd measure the supply across the processor, and see if *that* one is
at 5V too.
> There's some photos of that one too; the display is different each time you
> power it up.
That's because the video memory isn't initialized yet. It's containing
random data.
--
Martijn van Buul - Pino@dohd.org - http://www.stack.nl/~martijnb/
Geek code: G-- - Visit OuterSpace: mud.stack.nl 3333
Kees J. Bot: The sum of CPU power and user brain power is a constant.
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