Replace DS1220 / M48Z12 with anyPin nvram on Gottlieb Q*Bert / MP?

[tomservo]

My Mad Planets MPU is currently using the DS1220 / M48Z12 nvsdram. Is a 6116 nvram module such as the anyPin a drop-in replacement for those for the sdram's? Is anybody using the anyPin 6116 nvram in a gottlieb arcade board?

One reason I ask is because I had one of my Dallas sdrams go bad, and I replaced it with one I had in my kit, a DS1220AD-200 and the board wouldn't boot. I tried another DS1220AD-200, and the board still wouldn't boot. I replaced that with a DS1220AD-150 I had and then the board started right up. So it seems to me that the Gottlieb arcade board logic is sensitive to ram speed?

Just wondering if anyone has some more experience with the pinball 6116 nvram modules and has been successful in using them in the Gottlieb arcade boards?

 

[philmurr]

In theory they should work because RAM in Gottlieb boards is selected using /CE which is what FRAM needs. Be aware FRAM has a "limited" number of reads/writes (unlikely to be an issue in practice but I always shy away from using it for the main scratchpad RAM)

Before doing this I'd check the voltage at the battery-backed RAM which if less than 4.5 volts when powered up would prevent writes and may be the issue you're having, and not the RAM speed. Factory used HM6116-4 for the battery-backed RAM which is 200ns access.

 

[tomservo]

Thanks, I will check the voltage at the ram to make sure I'm getting at least 4.5V there. I'm wondering now if the 200ns sdram I tried were the 4.75V write protect version instead of the 4.5V version, which would make sense if the voltage is a bit low.

 

[Cmndr Brain]

I've tried to put Fram into my Q*bert (same boardset as Mad Planets) and I have not had any success. My only attempt was to try it and the game would not boot. Put the original 6116 back in and it works fine. I have not tried any more testing.