BIOS chip detect 12V, flash 5V

PeteV · BIOS Rookie Joined: 07 Apr 2004 Posts: 51

Hi!

This issue may interest someone, deep in BIOS flashing ...

During my dead mobo investigations I faced one strange issue on BIOS flashing, namely two same brand/type BIOS chips couldn't be re-flashed and seemed to be having bad blocks. But, after changing the flash voltage on the mobo, the chip was "cured by wonder" and allowed re-flashing all OK, i.e. came into life and work 100%!

This BIOS chip is a ST Microelectronics M28F101-150PI 128kB DIP32 chip. The mobo, on which I did make this "innovation" is a Shuttle HOT-569 v2.0 AT/S7 mobo with dual voltage flash option by jumper setting.
So, the BIOS chip had to be detected on 12V, but the flash voltage jumper changed to 5V after that before beginning the flashing with uniflash.exe.

I wonder, if this kind of trick may apply also on some other "bad-block" and to trash doomed chips, quite strange behaviour anyway ...

Best regards,

Pete V.

ruelnov · Posted: Thu Jul 15, 2004 2:19 pm Post subject:

I have heard of some EEPROM's requiring you to set the jumper to disable write protection (flash enable). Maybe this is the case with the ones you experimented. This should be documented in its datasheet, though.

PeteV · BIOS Rookie Joined: 07 Apr 2004 Posts: 51

Hi!

I think the flash enable jumper do have it's own function. That jumper is another one on the mobo, if existing at all, and do generally disable/enable the flash voltage on the mobo.

The dual voltage jumper, if existing at all, do give the selected voltage to the flash pin, and may also be functioning as disable, if not connected at all.

Regards,

Pete V.

maman · Posted: Thu Jul 15, 2004 7:42 pm Post subject:

perhaps, this family of flash chips is as weird as their M28F000 which is "quite well known" for its "incompatiblity".
_________________
-- Human knowledge belongs to the world --