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EPROM and EEPROM bios chips

Discussion in 'General Electronics' started by Phred, Jun 3, 2004.

  1. Phred

    Phred Guest

    I was flashing a new bios onto my P3 motherboard (Via Apollo Pro 133
    chipset) and in the middle of the write operation I stood up and trod on the
    power cord. The power went out and now, of course the board
    wont POST - just get a long beep, then nothing.

    I've tried disconnecting everything but the floppy drive and some ram and
    disabling onboard sound (via jumpers), installing an ISA graphics card with
    the same result.

    We have an old device programmer at work (EPROM Burner) and I have the bios
    files on floppy - but as far as I can tell the burner can't write to the
    type of EEPROM I have. It is a Winbond W29C020C, which is a 32 pin DIP
    package, 5.0V program voltage of 256k in size. I could burn the data to a
    27256 EPROM instead, but these are only 28 pin devices. Would it work if I
    burn say a 27C1001 which is a 32 pin device, but, of course, is 1024k in
    size.

    Are EPROMs and EEPROMs addressed in the same way (in
    read mode)? If this works it would allow me to boot the computer, physically
    remove the EPROM, install the EEPROM and re-flash the bios.

    BTW - the reason I was re-flashing in the first place was because the board
    would only see the first 128Mb of a 256Mb RAM stick, even though the
    documentation I got with the board said it should recognize the full 256Mb.



    Thanks
    Freddy
     
  2. Freddy,

    27C1001 is a 128x8 EPROM, so 1024kbit. You need a 27C2001 (or equivalent)
    http://199.239.248.95/Datasheets/ST/M27C2001_2383.pdf
    Address- and data pins are compatible, so are /CE ans /OE although the names
    differ. The only pins you have to look for are /PGM amd Vpp. According to
    the specs the actual value (high or low) does not matter, but they should
    not left floating.

    petrus bitbyter
     
  3. Phred

    Phred Guest

    Thanks petrus bitbyter!
     
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