Toshiba 4 Kilobyte ROM Circuit Board  
Written by AnubisTTP on 2025-01-03  

 

Description

This is an unidentified 4 kilobyte read only memory board which is built around an unusual chip, the Toshibia TMM121. The TMM121 is Toshibia's first EEPROM part number and was used in Toshiba's first microcomputer, the TLCS-12A, which is an unusual 12 bit system originally designed for use in automotive applications. While it is enticing to think that this board was salvaged from a TLCS-12A, it is much more likely that this PCB was intended for use in some unidentified piece of industrial control machinery. In addition to 18 TMM121s, this board also contains six TMM111Cs, an undocumented device. The TMM111C is a small 18 pin RAM IC with a white ceramic package and a round cavity lid.

More

Toshiba TLCS-12A Computer Circuit Board
An unidentified 4 kilobyte ROM circuit card containing 18 Toshiba TMM121 integrated circuits with various support chips.

Toshiba TLCS-12A Computer
The Toshiba TMM121 has an unusual construction, featuring a round cavity lid and window.

Toshiba TMM121 EPROM IC Die
Toshiba TMM121 die, shown at 40x magnification.

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