TMS0803

Texas Instruments TMS0803

With the TMS0803, Texas Instruments introduced the successor to the TMS0102 single-chip calculator in 1974. Unlike the TMS0102, which used discrete drivers for both segments and digits, the TMS0803 required only external drivers to power the seven-segment LED display. The chip integrates a 3520-bit read-only program memory (320 words x 11 bits), a 176-bit random-access memory (44 x 4 bits for data and flags)*, and a decimal arithmetic logic unit (ALU), alongside control, timing, and output decoders with integrated segment drivers for the display. This architecture results in a total complexity of approximately 5,500 transistors.

Due to a flexible design concept utilizing a programmable ROM mask, several design variants emerged.

A typical calculator based on the TMS0803 family performs the four basic arithmetic operations (+, -, *, /) and includes a percentage (%) function.

Family Members and Usage

TMS0801 ( Sinclair Cambridge )

TMS0803 ( TI-1500, TI-2500-II )

TMS0805 ( Sinclair Scientific )

TMS0806 ( Exactra 19 )

TMS0807 ( Canon LE-85 )