BIOS Updates forum

I have an old motherboard, FIC 486-GVT-2 which uses a 28-Pin EPROM (27C512) which is 64K

Now, the last BIOS (4 years newer than the current one) for this board is 128K, so obviously I can't use the old chip

But the socket is 32 pin, and with the old chip removed there is screened on the board "FROM - 128k * 8" so I expect I can use a 1mbit/128K part in there.

My question here is: is it electrically compatible? For example, if I were to use a 29C010? as it is, the current chip is plugged in so pin 1 of the chip plugs into pin 3 of the socket:

http://flickr.com/photos/agent_24/2491103673/

http://flickr.com/photos/agent_24/2491938548/

The pins are compatible bar pin 28 which becomes pin 30 and changes from Vcc to NC, and Vcc moves to Pin 32.

As for pins 1, 2 & 31 for support in the socket I have no idea.

I don't need to be able to program the new chip in the PC but it would need to boot up and work normally obviously.

Or would I only be able to use a EPROM like 27C010?

Does anyone have any thoughts on this?

My question here is: is it electrically compatible?

yes. pin30 is NC on the 29C and should be shorted to pin32 on the socket. take a multimeter and check it. for the other pins: _WE is Write Enable which _should_ make it possible to flash the 29C on this board, too. but to reduce risks i wouldn't test that. except you have a stash of 29Cs floating around somewhere ;)
A16 is the address line you need for the additional 64k on the 29C and pin1 is NC anyway.

my recommendation is: check if VCC is connected to pin32 on the socket. if it is not: just short it to pin30. flash the 29C with the latest bios and plug it in.

Yep, pin 32 has 5 volts on it..

I guess I'll give it a go and see what happens - but I will not try flashing on that board just incase...

Operation was successful Thanks for your help!

Unfortunately the problem I was having wasn't solved by the BIOS update

Oh well...

Update: problem was fixed - turned out to be a wrong jumper setting!