Texas Instruments Produced many cartridges for the TI-99 line of computers. They also made it as hard as they could to keep 3rd party software companies from producing cartridges for the TI-99. Of course, this did not quite work out as many companies produced cartridge based software for the TI-99.
The below is from a TI training manual:
• computer console
• TI Color Monitor or TV with adapter (Video Modulator)
• cartridge (contains a printed-circuit board with chips)
The cartridge medium is an excellent way to take advantage of the wide assortment of preprogrammed software currently available. Most of these cartridges available require no extra peripherals because they plug right into the console. Cartridges, most of which are not erasable, are fast and very easy to use. You can even store your own data (temporarily or permanently) on the specialized Mini Memory cartridge.
To Insert Solid State Cartridges
Turn on your console and monitor or TV. The TI master title screen should automatically display on your screen.
Insert a solid state cartridge firmly into the slot to the right of the keyboard. The screen will go blank for a second and the the TI master title screen should reappear.
Press any key to move to the next screen.
Select the name of the cartridge you inserted (usually by pressing the number 2--the number 1 will always take you into TI BASIC).
To Remove Solid State Cartridges
Return to the master Ti title screen by pressing PCTN and the “ key. or by exiting according to instructions included in the cartridge’s program.
Remove the cartridge from its slot.
In Case Of Difficulty
If a cartridge does not seem to operate properly, try reinserting the cartridge. Or, if the screen locks or produces unusual displays, try turning the console off and waiting a few seconds before turning it back on.