Hi,
I have never used an AT89S52 with external 64K code memory. Can you please suggest which IC would be the best one?
I only need external code memory as the internal RAM would be sufficient for my purpose.
The only criteria I am looking for is ease of programming the ROM chip. I cannot afford to buy myself an expensive programmer and hope to create my own home brewed ROM programmer.
The only way to use as external code memory is to use parallel EEPROM/ Battery backed up RAM or EPROM and use PSEN to read the memory. You will need an LS/HC373 like device to separate low byte address and data bus for connection to the EEPROM/EPROM. Serial devices will not work for this application as they have to be bus compatible with 8051.
If any further doubts, please continue.