How much of a ][ is needed to twitch?

[Tristan Mumford <xtristan.xmumford@xgmail.xcom>]

This may seem like an odd question, but how many components can I pull out
of an apple ][, well an identical clone anyway to see some signs of life?

I'm in the mood to attack my infirm clone to try to get it running again.
As it is I'm fairly certain the problem isn't the CPU or ROMS. About a month
ago I was doing a random pull test. Essentially pull a chip, power up and
see what changed. The most difference that pulling a chip made was making
the screen all white. Other than that all that really changed was the
pattern of 'garbage' on the screen. Although I'm sure the garbage pattern
would probably tell a story to some people it doesn't to me.

I'm hopeful of a solution that doesn't involve me blindly replacing chips
until I find the culprit.

This all reminds me, is there an Apple2 schematic available? It would help
me to no end... and also help me with a conceptual future project. A
reduced logic Apple2 clone. Nothing exciting. Just integrate the RAM and
ROM chips to reduce chipcount, and a few other minor fiddles for my own
contentment, like AT/X board layout and PS/2 keyboard support. It's not a
short term project by any means, but I know it's by all means achievable.

Anyway, back to it. The clone ][.
I used a replacement power supply to eliminate that. I've pulled the ROMs,
CPU, and chargen with no real effect. Pulling various RAMs affects the
pattern a little like leaving alternating gaps in the garbage.
Strangely enough the patches of random garbage slowly dissapear and turn to
black. After a while no more patches stabilise though.

I know I've posted about this in the past, but I still want to fix it and
I'm after any input that can be given on a systematic method.

Tristan.


-- 
-----> http://members.dodo.com.au/~izabellion1/tristan/index.html <-----
=====       It's not pretty, it's not great, but it is mine.       =====