The P-Card by Texas Instruments is an expansion card for the TI-99/4A Peripheral Expansion System which gave the TI-99/4A the capability to use and program software for the UCSD Pascal P-System. For those not familiar with the P-System, it was an early attempt at platform-independent software and all software written in accordance with it's specifications were to be usable on any system, regardless of platform, which was using the P-System software, and without modification. The P-System was available for quite a few systems, including the TI-99/4A, IBM PC-XT, and Apple II. The P-Card for the TI-99/4A actually took over the computer and early versions required that you physically remove the card in order to use the TI in it's normal modes. Later versions though added a switch to the rear of the card that allowed you to turn it on and off without removing it from the system. When switched on, the P-Card boots from it's onboard ROM and directly into the P-System and it's menus.

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