| Designer | Texas Instruments |
|---|---|
| Bits | 16-bit |
| Introduced | 1976 |
| Design | CISC |
| Endianness | Big |
| Registers | |
| PC, WP, ST | |
| General-purpose | 2 internally located in processor (WP, ST) 16 × 16-bit workspace located in external RAM |
The TMS9900 was one of the first commercially available, single-chip 16-bit microprocessors.[a] Introduced in June 1976, it implemented Texas Instruments' TI-990 minicomputer architecture in a single-chip format, and was initially used for low-end models of that lineup.
Its 64-pin DIP format made it more expensive to implement in smaller machines than the more common 40-pin format, and it saw relatively few design wins outside TI's own use. Among those uses was their TI-99/4 and TI-99/4A home computers, which ultimately sold about 2.8 million units.
Microcomputer-on-chip implementations of the 9900 in 40-pin packages included the TMS9940, TMS9980/81, TMS9995. The TMS99105/10 was the last iteration of the 9900 in 1981 and incorporated features of TI's 990/10 minicomputer.[1]
By the mid-1980s the microcomputer field was moving to 16-bit systems like the Intel 8088 and newer 16/32-bit designs like the Motorola 68000. With no obvious future for the chip, TI turned its attention to special-purpose processors like the Texas Instruments TMS320, introduced in 1983.
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