Re: Dead_PET_2001_with_6550´er

From: Ethan Dicks (
Date: 2002-04-16 17:56:25

  • Next message: groepaz: "Re[2]: Dead_PET_2001_with_6550´er"
    --- Klaus Seiner <> wrote:
    > Hello!
    > I have a dead PET 2001 (first version with 6550´er RAMS). On startup it
    > shows just garbage chars on the screen. I suppose the ROMS are dead.
    Not necessarily.  I've seen dirty sockets or loose chips cause all
    sorts of problems.  I had an old 8K static RAM PET that would not
    work unless there was a cardboard shim under the middle of the 
    motherboard.  Something about board sag and loose socket contacts.
    You might pull each ROM and RAM chip, inspect for tarnish (if they
    are silver-plated pins, they will be black after this many years) if
    clean, just re-insert.  If not, I'm not sure the best way to remove
    visible silver oxidation from CMOS SRAMs without generating static.
    > Can anyone (or has anyone) tell me how to replace the original ROMS with
    > EPROMS? I guess socket adapters are needed to. And which kind of Eprom
    > to use?
    Personally, if I were going to replace the ROMs, I'd consider replacing
    the sockets, too, with machined (turned) pin sockets, or making an external
    ROM board for the edge connector (also with machined pins).  You could
    put all of the ROM code in a single chip.
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