MRM AppNote: Expand to 1Meg of RAM
This AppNote explains how to add an additional 512K of RAM to an MRM with 512K of RAM.
Stack additional 512K RAM chip on top of existing 512K RAM chip. Solder all pins of the two RAM chips together EXCEPT pins 22 (ce), 24 (oe) and 32 (vcc). Pins 22 and 24 should not be connected to the corresponding pins on the existing RAM chip and should be connected together and then connected to CS5 which has a pad located adjacent to pin 22. Pin 32 should not be connected to pin 32 on the existing RAM chip and should be connected to VCC which has a pad located adjacent to pin 32.
CPU32BUG has been modified to support 1Meg of RAM. The new CPU32BUG file is MCBUGMEG.S19. You will need to download the file and load it using BDM following the same instructions for loading MCBUG.S19. The new CPU32BUG rearranges the MRM memory map by moving the flash from $80000-$FFFFF to $800000-$87FFFF, and placing the new 512K RAM at $80000-$FFFF. The existing 512K RAM remains at $00000-$7FFFF. See MRMTESTMEG.ZIP for a compatible version of MRMTEST.