Quote Originally Posted by kilohertz View Post
ok thx for the replies.

As mentioned I don't want to use EPROMS as I will be making many changes...hence the eeprom or flash. Also as mentioned my programmer can't program the 27sf512...trying to work with what I have.

cheers
I'm very familiar with chip programming. I'm not familiar with the AT28C64 so I looked at Mouser for information: https://www.mouser.com/ProductDetail...3SuxMz5Q%3D%3D and then looked at the data sheet: https://www.mouser.com/datasheet/2/2...01-1180850.pdf

The 1227747 uses a 4K chip. The AT28C64 is a 64K chip just like the 27SF512 is a 64k chip. After reading the AT28C64 data sheet, it appears to me the AT29C64 can be used in the 1227747 with "Offset Programming" because only the bottom 4K memory of a 64K memory chip is needed for the 1227747. Additional information about programming with offsets can be found on the Moates.net website:http://support.moates.net/programmin...using-offsets/



Offsets for a 4k chip being programmed into a 64K chip
Microchip AT28C64
Buffer -> 000000 -> 000FFF or Hexadecimal for 4K chip memory size
Address -> 00F000 -> 00FFFF or Hexadecimal addresses to program only the bottom 4K addresses of a 64K chip

For example if you were going to program the AT28C64 for the second generation TBI computer 16197427 which uses a 64K chip no offset is needed.
Buffer -> 000000 -> 00FFFF or Hexadecimal for 64K chip memory size
Address -> 000000 -> 00FFFF or Hexadecimal addresses to program all addresses of a 64K chip

dave w