Smith-Corona Marchant I Calculator LSI  
Written by Accutron on 2008-01-31  

Devices included in this entry:

TI TMC1771SC calculator LSI (40-pin ceramic LCC; pictured in thumbnail)
TI TMC1772SC calculator LSI (40-pin ceramic LCC; pictured in thumbnail)
TI TMC1773SC calculator LSI (40-pin ceramic LCC; pictured in thumbnail)
AMI 479A calculator LSI (40-pin ceramic LCC)
AMI 480B calculator LSI (40-pin ceramic LCC)

The Texas Instruments TMC177x series, used in the Smith-Corona Marchant I portable calculator, is the fourth calculator chipset produced by TI. The TMC177x series slightly predates the historically important TMS0100 series calculator chips, and is probably similar in design to the handful of other TMC17xx and TMC18xx LSI chipsets which were developed for Canon and other manufacturers in 1970 and 1971. Chips of this type were also used in the SCM Cogito 410 desktop calculator, but were replaced with ceramic DIPs in the Cogito 412 and 414.

The primitive leadless carrier is the most striking feature of these ICs. Note the asymmetrical design, built to interface with preexisting edge connector components. More modern leadless designs feature pins exiting the carrier on two or four sides, and require a custom leadless socket.

The function of the AMI ICs is unknown, but they share the same custom SCM carrier.

Texas Instruments TMC1771SC, TMC1772SC and TMC1773SC calculator LSI, featuring a unique leadless ceramic carrier and enameled grey traces. This is the earliest leadless carrier currently known.

AMI calculator LSI, two ICs of unknown function.

This article is part of the [Digital Integrated Circuits] exhibit.

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