A microprocessor manufactured by Texas Instruments around 1980, which was based on the TI 990 minicomputer design. It had a few neat features, a 15 bit address bus, 16 bit data bus, and it kept all but two registers in the current memory area (making it possible to change contexts very easily, but requiring fast RAM). For a time, it provided potential competition to Intel, yet when IBM choose the 8088 for their PC, the 5150, this changed, and over the next few years the design only saw use in some implementations destined for embedded use.
The TMS 9900 was the CPU in the TI-99/4A.