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Flashing S3 Bios?

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First post, by AppleSauce

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So I have a few S3 Trios that happen to suffer from the washed out black level bug :

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I read it might be possible to mod the bios to get rid of the issue.
How would I go about dumping the original bios chip and flashing the bios to a new chip ,
and what kind of type of rom chip would you need? , since I might want to keep the original as a backup.

Also what flasher device would you recommend to do the job?
Is the Tl866 II plus still the best choice or is there something better now for around the same price?

Reply 1 of 1, by mkarcher

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Those cards use 28-pin 32KB (256kBit) parallel EPROMs. The original ones are likely cheap "one-time programmable (E)PROMs", which is the silicon of a UV erasable EPROM in a cheap plastic case without the quartz window. You can't reprogram those (well, some people managed to erase OTP EPROMs using a medical X-Ray device, but that causes damage to the chip, and they are toast after a couple of erasures), so you can just keep the original chips as backup chips.

Any 5V 28-pin DIP parallel EPROM/EEPROM/flash chip with at least 32K x 8 will work as replacement. Be careful with chips that have an "L" in the model number, as they are often "low-voltage" (i.e. 3.3V) only and might be destroyed by applying 5V. Winbond W27C256, Atmel 28C256 or Atmel 29C256 are possible flash chips. The TL866 is still very common, I didn't yet hear of a newer or cheaper flashing device that is able to program parallel ROM chips. There are modern cheaper programmers for serial flash chips, though.

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