TI-990

The TI-990 is a series of 16-bitminicomputers sold by Texas Instruments (TI) in the 1970s and 1980s. It served as a replacement for TI's earlier minicomputer systems, the TI-960 and the TI-980. The TI-990 features several unique innovations and was designed to be easier to program than its predecessors.

Among its core concepts is the ability to support multiprogramming using a software-switchable set of processor registers that allowed it to perform rapid context switches between programs. This is enabled through the use of register values stored in main memory that could be swapped by changing a single pointer.

TI later implemented the TI-990 in a single chip, the TMS9900, one of the first 16-bit microprocessors. Intended for use in low-end models of the TI-990, it retained the 990's memory-to-memory architecture. This chip was widely used in the TI-99/4Ahome computer, where aggressive cost-cutting measures presented significant performance disadvantages.