The Supercart adds 8K of battery-backed RAM to the Editor/Assembler module. The utility of this device derives in large part from its capacity to provide E/A module menu access to assembly language software. In effect, this means you can write your own 8K battery-backed command module software.
Do it yourself projects:
- http://www.mainbyte.com/ti99/supercart/supercart.html
- http://www.mainbyte.com/ti99/supercart/supercart_4bank.html
Purchase a pcboard for this:
There were commercial products available on the market for a time in the 80’s as well.