I salvaged a Microchip 27C256 15/P from a graphics card in an old computer.
Datasheet
Can I format this and use it for external memory in a microcontroller like an Arduino?
EDIT: I ask this here since Google brings up tutorials for 8-DIP EEPROMs, and I don't want to damage mine.
There is no formatting involved.
The problem with that part is that it is parallel. Quick look at datasheet suggests that it requires about 18 pins to control (A0-15, plus a couple others), and another 8 pins to get the output 
I would not have bothered salvaging that. I'll bet it was a pain to get off too.
Not really, no. It was socketed. 8)
I have a Mega, so pins aren't in short supply. How EXACTLY would I wire it?
The 27C256 is a 32K x 8 PROM not an EEPROM. If it has a window on top, it is an EPROM which is erasable using an ultra-violet light.
No window on top.
Aaagh! good catch.
Yeah, it's an EPROM not an EEPROM. You can't erase it :-/ All you can do is read the firmware for whatever you pulled it out of.
Well, darn it. I guess then I will be looking at the firmware for a 3d renderer forever...
legonick22:
Well, darn it. I guess then I will be looking at the firmware for a 3d renderer forever...
Well, you can buy an I2C eeprom for less than a cup of coffee, shipped with a breakout board, and it only takes 2 pins... http://www.ebay.com/itm/171325005348 (no endorsement of that vendor - he's just the first one that came up)
Back in January, I purchased some 24LC128 EEPROM's from DigiKey ( 1-800-344-4539 ) for 73 cents each. The ordering P/N is 24LC128-I/P-ND. They work perfectly with my Arduino. Hope that helps.