Hi Guys, I'm trying to research which EPROM i need to work with my ECM and Im not coming up with any definite part numbers. I have a 7477 ECM. Will AT27C256 AT28C256 AT29C256 all work? I Don't understand the diference... Thanks!

 

1) AT27C256 is one-time programmable read only memory (OTP EPROM) manufactured by ATMEL - you do not want this EPROM since you want to be able to re-program your EPROM more than once. Once you burn it can not be changed - it is like old ROM chips from late 70's and early '80s.

2) AT28C256 is a high-performance electrically erasable and programmable read only memory (EEPROM) manufactured by ATMEL. Full order information for a typical 28PDIP part AT28C256-15PU. This part is commercially available:
http://parts.digikey.com/1/parts/541...c64b-15pu.html


3) AT29C256 is a five-volt-only in-system Flash programmable and erasable read only memory (PEROM). This part is not recommended for new designs and was not available in 28 Pin PDIP. This part is of little use to you unless you have PLCC or TSOP package to 24P DIP adapter.

 

Hey RF, Thanks again. I decided to go with moates.net and I purchased the Burn2 programmer, the G2 adapter, and AT29... chips. Mainly because of the compatability with the programmer. These should work with a 7747 ECM right?

 

IRC Moates offers 27SF512 which is 512k vs 256k EEPROM. Yes, it should work, but simply double check against compatibility chart of your burner. Moates always stands behind his products and support question gets answered very quickly.

A word of practical advise as this almost always trips noobs. Make sure that you read (and understand) how set correct start address for your EEPROM's as it varies depending on the size of chip. Stock 1227747 binary is 4k big (or 32728 bytes). CPU reads data stored in EEPROM from the highest EEPROM address down:
File Size ||| Chip |||| Buffer Start -> End |||Chip Start -> End
4k (4096) | AT29C256 | 000000 -> 000FFF ||| 007000 -> 007FFF
http://www.moates.net/manuals/FlashAndBurn.pdf

Stock CPU simply can not address (without some help) the remaining space available in the new (256, 512 k EEPROM chip). I would suggest practicing burning stock BIN files and reading them back to get comfortable using your burner and software. GL

//RF