Genesis:FRAM Mod

First decide single or multi banks, yadda yadda.

The method was mentioned to be possible by Xaranar on a long-dead forum. WESTeeX1 was the first to use bankswitching to allow four separate 64kb banks to be usable on a 256kb FRAM module.

Replace the MB8464A-10L chip on Model 1 CD. (model 2 IC?)

Replacement chip candidates include:

• FM16W08-SG - 64kb (stock SRAM size, go with this unless you plan on bankswitching)
• FM18W08-SG - 256kb (extra space not seen by BIOS, but can be bankswitched).
  • If you use this module and don't plan on bankswitching, lift Pin 26 and attach it to GND since it is used as an address line and would be connected to the battery backup.

Some chips are sold without "-SG" on the end. -SG just means it's a SOIC package type (instead of -PG which is thru hole pins, which is not what we want).

Just lift pin 26 off of the motherboard and attach the switch to pins 1 and 26. This lets the chip act as 4 separate on-board memory cards, which you can swap between using a physical switch.