Quote:
Originally Posted by julie_m
If "tanning" is a problem for you, it was certainly possible in the days of the BBC Micro to use a 6264 (I think that was the part number) 8k * 8 SRAM IC with an auxiliary lithium battery back-up supply, as a substitute for a 2764 EPROM. The BBC used only memory ICs designed to run from a simple 5V supply (no +12V, -5V or -12V). Most of the pins are just passed straight through; the rest are carefully bent out of the way and the IC stood in a 28-pin DIL socket.
|
Yes, the 6264 is the one. I used a setup like that for quite an ambitious 6502 development project in the late 1980s. My 6264 had three AA cells in a holder on flying leads connected to its power pin and ground. The power pin was bent upwards so it didn't contact the socket. I had a bit of Veroboard with an address decoding latch on it connected to the BBC Micro's 1MHz bus so that the 6264 RAM appeared in 256-byte pages at &FC00 (I think). Code was assembled (using the Beeb's built in BASIC assembler) 256 bytes at a time to that address, with the origin set to the address it would finally end up at. Run the assembler, pull the chip out of the socket (power still on) and plug it in to the EPROM socket on the device I was developing. Hit reset and the code ran. Rinse and repeat.
It worked fine, with only very occasional data corruption problems. It was very cheap, as well, which was a big advantage at the time!
Conclusion: if erasing EPROMs is a pain, a battery-backed RAM chip will work fine.
Chris