Key in Accession Folder. Key ID: C2132 Chicago Lock. Donor writes: "The TI960A minicomputer was a 16-bit machine designed by Texas Instruments for industrial process control and transaction processing. The first shipments appear to have been circa 1972. TI appears to have been the first users of semiconductor memories from a new semiconductor company called Intel. Strewn throughout the machine are boards full of Intel 1101 RAMs, the first 1K-bit DRAM. The TI-960B was a follow-on machine which had greater peripheral slot capacity, and an Arithmetic Option for fast integer multiplication and division (useful for accelerating closed-loop servo algorithms in industrial automation). These minicomputers are architecturally interesting because of the way memory was used to map local register sets so as to allow rapid context changing for servicing interrupts. These systems used a 4 MHz clock to pace a CPU devised entirely out of TI's nascent TTL logic family. The internal design was microprogrammed using MSI TTL ROMs custom manufactured by TI. TI also manufactured the large multi-layer printed circuit boards for these computers, additional evidence of this computer family being a vertical integration project for TI of the early 1970's. Instructions were 32-bits in length, while the main memory was organized in a 16-bit fashion. Due to the architectural influence for rapid transaction processing, I/O was memory mapped in peripherals which could be quickly accessed at the bit-level using a Communications Resource Unit (CRU) facility. The CRU offered logic which was akin to barrel shifter used in conjunction with memory read and write data exchanges with CPU registers.. Like other machines of bygone eras, these minicomputers had unusual quirks as well -- a notable feature of the TI-960's is that the least significant bit in memory or register space is numbered starting from the left, instead of from the right, as in most conventional CPUs. This is not so terrible as it sounds, once you get used to it -- serial communication channels of the day exchange data in such a left-to-right signaling order. As this machine had an architectural sweet spot for transaction processing, this is a relatively natural bit-ordering scheme. This minicomputer family is the architectural antecedent for TI's later TMS- 9900 LSI microprocessor of the late 1970's. While the TMS-9900 was suited for similar applications as the minicomputers, it was 2-4 times slower than it's TTL-only ancestral brethren. For a time, the TMS- 9900 was the only 16-bit processor available to system designers. This was the processor of choice when Tektronix, Inc. embedded this minicomputer-like microprocessor within it's 7854 Waveform Processing Oscilloscope, which shipped in 1980. The machines in TCM's collection evidently were part of the credit verification MIS system for JC Penny in the Pacific Northwest until the early 1980's."