Toshiba TMM121 EPROM Integrated Circuit Chip  
Written by AnubisTTP on 2020-12-28  



This strange looking chip is Toshiba's first EPROM device, the TMM121 UV-erase EPROM. Intended to be a competitor to Intel's 1701 UV EPROM, the TMM121 can store 256 bytes in stable UV-erase memory. The chip has an extremely unusual flanged round lid with a central window, which allows the die inside to be exposed to UV light when erasing is desired. The die is housed in a white ceramic carrier with bottom-brazed pins and a large locating notch. The TMM121 was used in Toshiba's first microcomputer, the TLCS-12A, which is an unusual 12 bit system originally designed for use in automotive applications. We do not know the date of manufacture for this device, but it was likely released sometime around 1973.


Toshiba TMM121 EPROM Integrated Circuit Chip
Toshiba TMM121 UV-erase EPROM, at rest. The example shown here is suffixed TMM121-1 and has a date code of 8B.

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

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

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