Canon Pocketronic

Today we can assume that the people at Canon Inc. were heavily impressed by the Cal-Tech project started at Texas Instruments in September 1965 and finished in 1967. Both companies developed together the Canon Pocketronic, the first calculator based on Large-Scale-Integrated (LSI) circuits. A total of three LSI circuits was necessary to do the four basic calculations with numbers of 6 to 12 digits. The production of the calculator was done in Japan but uses a lot of components manufactured by Texas Instruments. Beside the LSI chips they delivered the print head of the thermal printer and the transistors. Please note that the paper is running out in a horizontal matter compared to the later vertical style of printing calculators. A nearly identical calculator was manufactured from Canon for Monroe. Explore the rare Monroe 10.

This Canon Pocketronic is the most important calculator in the history of Texas Instruments and we take a closer look at it.

The side view of the Pocketronic reveals a rather sleek profile and shows the small slit for the "serial" thermal printer used to display the results of the calculations. Please keep in mind that in 1970 numeric LED displays weren't commercial available. The thermal paper was sold in boxes of five tape cartridges.

Dismantling a Canon Pocketronic manufactured in 1971 reveals an engineering marvel with less mechanical and electronic parts than expected neatly stuffed into the top shell of the case while the bottom shell is occupied with a total of 13 rechargeable NiCd batteries.

The thermal printer consists mainly of a transport mechanism (right hand side of the picture) and the print head (left hand side of the picture). The electronics of the printer is placed next to the transport mechanism, the featured unit sports the so-called correction chip that was introduced around 1973 or 1974 to fix some timing issues of the original discrete design.

Most of the electronics of the Pocketronic is not immediately visible, it is sandwiched below the electronics of the printer mechanism and fitted into three Integrated Circuits (ICs). These chips with part numbers TMC1730, TMC1731, and TMC1732 are manufactured in a "state of the art" 10-micron 1-metal PMOS process and using Dual-Inline Ceramic or Plastic (DIC/DIP) packages with 40 pins and 28 pins. Please find an overview of more later ICs developed and manufactured by Texas Instruments for Canon here.

The backside if the Pocketronic provides a condensed form of the instructions manual, the serial number and the voltage rating of the external charger.

One of the PCBs of the Pocketronic changed over time, please find picture of three different calculator versions here.

The Pocketronic was later replaced with the Pocketronic II, creating a massive headache for both Canon's Product Manager and TI's Engineering Team.

The next calculators in Canon's line was the L121 using four instead the three LSI circuits driving a 12-digit Nixie tube display. Within some month both the desktop model L100 and the the wonderful pocket sized LE-10 appeared.

Don't miss the Sharp EL-8 and Sanyo ICC-82D.

If you have additions to the above article please email: joerg@datamath.org.

© Joerg Woerner, December 5, 2001. No reprints without written permission.