Flashing 3.3V Flash ROM on 5V systems

Only for programmers and BIOS gurus with technical questions.
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ruelnov
Master Flasher
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I've got a few dead boards to revive having a corrupted BIOS image, but the flash ROM supply voltage is 3.3V.

I know I may have to look for boards with same supply voltage to the flash ROM to do the hotflash, but the quick fix I'm thinking about is to use my existing board having a 5V flash ROM supply voltage.

I would temporarily disconnect the 5V supply after the system has booted to clean DOS, then inject a 3.3V supply voltage to do the hotflash.

Do you think this is a sound plan? Has anybody tried this approach?
sulbert
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Are you trying to use the parallel programming mode of the FWH/LPC chips (haven't seen any board with a 3.3-V parallel flash ROM)?
ruelnov
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I'm not sure what you mean by parallel programming mode, but I wanted to hotflash a W49V002F flash ROM (3.3V only erase/program) on a "standard 5V only" flash ROM socket found on most boards.
sulbert
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Take a look at the W49V002FA datasheet. I mean the Programmer (bus) interface mode. AFAIK normally, when on a motherboard, the flash chip is used in FWH mode.
ruelnov
Master Flasher
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I see your point, and the flash ROM needs to be in FWH mode to be able to communicate with the chipset (as Uniflash would be used to do the hotflash).

And do you think flashing this 3.3V flash ROM is possible on a 5V system if the supply voltage is changed to 3.3V?
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