Texas Instruments TMS0970 / TMC0900

Texas Instruments introduced the TMS0970 in March 1976 as pin-compatible and cost-optimized upgrade of the TMS0950, effectively dropping 4 resistors and 1 capacitor from the printed circuit board (PCB) and shrinking its silicon area by almost 30%.

Based on the Digit Processor architecture of the TMS1000 Microcomputer and featuring a large program memory with 1,024 Bytes ROM (Read-Only Memory) capacity and a flexible RAM (Random-Access Memory) with 256 Bits organized in 4 files of 16-digits, each plus integrated segment and digit drivers for an 8-digit LED display and everything powered by a small 9V alkaline battery, the TMS0970 found its way into many products. Most successful was certainly the Little Professor introduced in 1976 but Texas Instruments sold a basic design (TMS0972, four-banger with 4-key memory) to third party manufactures, too and it proofed to be very successful with OEMs in Hong Kong around 1977 and 1978 with what we call here in the Datamath Calculator Museum "Far East Generic Design I, Design II, and Design III".

With millions and millions of the TMS1000 Microcomputer deployed in hundreds of customer designs by 1977 and the TMS0970 basically a very cost-effective way to implement electronic consumer products, Texas Instruments started marketing the design as TMC0900 (C as in Customer) and the chip found its way into various electronic games and toys.

With calculator prices dropping in 1977 significantly below the $10 mark, Texas Instruments introduced in 1977 both a cost-optimized version of the TMS0970/TMC0900 in a 28-pin Shrink Plastic Dual In-line Package and a design variation replacing a conventional [ON-OFF] switch with a simple push-button [ON] key as TMC1990.

with permission of the author