Schematic & TMS0107 NC Calculator Chip

The TMS 0107 NC, also called TMS0107, is a calculator chip manufactured by Texas Instruments. It is a computer chip capable of performing basic mathematical operations, scanning the keyboard, and providing a multiplexed output for display. It has a single Arithmetic Logic Unit (ALU), and static memory for storing a single 10-digit numerical value.

In order to provide a display, this chip required four support chips to drive a 10-digit LED panel.

Pinout

This chip requires both positive and negative voltage rails to operate, and I measured +9 V on pin 28, and -9 V on pin 15.

The clock pulse is fed to pin 1. Ports d1 through to d11 are for scanning the keyboard, and pins 16 through to 24 provide signals to the display driver chips.

Clock Oscillator

A pair of transistors in a bi-stable configuration generates the digital clock pulse, which is around 255 kHz.

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