Navarone
Cartridge Expander

The Navarone Cartridge Expander allowed one to have 3 cartridges plugged into the console at the same time. There is a 3-way switch on the expander which allowed you to choose which cartridge to use. After choosing the paticular cartridge you then hit the reset button on the expander which then reset the computer. The expander plugged into the cartridge port on the TI-99 in place of a cartridge

Here is a front view of the Cartridge Expanders circuit board.

Here is a view of the back of the Cartridge Expanders circuit board.