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512k HM628512 cartridge problemPosted: Mon Nov 23, 2020 1:29 pm
Hi!, I just build a 512k SRAM cartridge with an Afterburner donor for use with the smsreader.
I used the hitachi HM628512 chip, and followed this steps from mike g:
Lifting pins 1 22 29 (32 is vcc in aferburner so I soldered normally in his hole).
Pin 1 went to a14 rom in the mapper, pin 22 to CE in the mapper and pin 29 to the write protect switch as the cartrtidge tutorial says.
I used the ICL7673 to battery back the sram, BUT with this memory chip, I dont have a second inverted chip enabler pin for standby battery mode,
So, first I tried with pin 6 of the 7673 unconnected, no big deal, the sram cant keep the rom after I disconnect the cart from the programmer.
Second, soldered the pin 6 of the 7673 to the CE pin in the SRAM (pin 22) and the cart worked. The problem is that I get data corruption and graphic glitches.
Any thoughts? Thanks in advance for your help.