Technically equipped is the TI99/4A with a TMS9900 processor (16-bit address bus / 8bit data bus / 12MHz clock) as CPU. Its memory comprises 16K RAM - expandable to 48KByte - and 64kBytes ROM/GROM. GROMs are special ROM chips with integrated address counter programmed in a special language named GPL. The video chip, a TMS9918A(in Europe TMS9929A), integrates 3 graphics modes and 1 text mode. The maximum screen resolution is 256 * 189 pixels in 16 colors. Up to 32 Sprites can be Simultaneously displayed and managed, without burdening the CPU. The sound processor includes 3 audio channels at a frequency of 110Hz to 44733Hz and a programmable noise channel. In addition, via an externally connected speech synthesizer also (American) speech can be reproduced. In the console are also connectors for joysticks, a interface for commercially available cassette recorder as storage medium, and the expansion and the module port.

The TI99/4A is expandable in any way. For this only an expansion-/P-Box is required. It takes all expansion cards (similar to today's PC.) By default, you can find there an interface card (1x Centronics and 2x RS232 expandable up to 4x RS232), a floppy disk controller ( with Shugart bus, up to 4 180K disk drives) and 32k memory expansion. Later extensions werefor example a RAM disk with up to 4 Mbytes, a improved graphics card (256 * 424 pixels in 256 of 16 million colors or 80 characters per line in 4 colors) or a SCSI card.
An additional expansion option provides the module port on the top of the console. Here you can plug in so-called Solid State modules. These include programs in ROM or GROMs (up to 64kbytes GROM and 32kbytes ROM). The can handle user programs like Multiplan (yes, even Microsoft has worked for TI), database management such as DATA MANAGEMENT&ANALYSIS, educational software and games, but of course fun games from simple up to high-level like CHESS. Even Atari and Sega produced such toys.

In addition, there is a ton of software on tape or disk. Texas Instrument reported 1981 the globally available programs with over 1000, meanwhile there are a lot more. Prerequisite for this was the availability of programming languages. Already in the console was installed TI BASIC, a simple but easily learnable standard. As an extension there was the EXTENDED BASIC. In addition there were UCSD Pascal, TI LOGO and ASSEMBLER (Machine language) available. Later added were c99, Turbo-Pascal, Cobol, Forth and pilot and various exotics.