PET startup sequence?? (was LF: Commodore PET schematics, troubleshooting info)

From: Dave Dunfield <>
Date: Tue Aug 10 20:45:44 2004

At 17:43 10/08/2004 -0700, you wrote:
>Hi Dave
> A common failure item in these old machines is the RAM.
>Any failure of the RAM makes things like subroutines fail

Yeah - that did occur to me - hard to diagnose for certain - all the RAM's are
soldered in.

I did remove and socket the ROM's today - so with an EPROM emulator I can put
boot code in fairly easily - anyone know what the minimum I need to do to setup
the video and any other essential hardware is? Also a memory MAP would be
handy (I think I saw one in the Archive - I'll look, however if anyone knows
where the RAM limits are and where Video memory is - could save me sime time.

If I can figure out where the RAM is, and how to write to the screen, I can
boot a small RAM test in the Kernal ROM space.

dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools:
com             Vintage computing equipment collector.
Received on Tue Aug 10 2004 - 20:45:44 BST

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