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I was looking for a CMOS ram replacement for my friend's pinball machine and came across a 5114 NVRAM module that appears to be a popular replacement for the 2114 family of CMOS RAM chips.
This obviously made me think of replacing the 5514 chip in my PolySix (no battery, plus a chip available at Digi-Key or Mouser, and extra address space for other projects); a quick conversation search here didn't turn up anything NVRAM-related. The module uses a Cypress FM16W08, which appears to be compatible with the 5514 (obviously not a drop-in replacement, but it has all the requisite pins). Seeing at the "pinball" chip+adapter costs a minimum of $25+shipping (for me), one could alternately use a cheap SMT breakout to mount the chip and solder the required leads.
The only caveat (well, the one that's documented) is that the /CE line has to be toggled for every read/write operation. The 367's /CE is on pin 8, which is controlled by IC25 (quad NAND gate), which is tied to the write enable (R/W), /WR (pin 10), /RD (pin 8), pin 34 (p17), & pin 4 (/REST) of the CPU, and pin 7 of IC5. I haven't connected my logic analyzer as of yet, thinking that someone here has tried to connect NVRAM before.
Any insight would be appreciated
- Andrew