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Canon Canola L1428 Electronic Calculator

This machine isn't particularly noteworthy in terms of technology or unusual features, but it is still interesting. It was made in 1980, quite some time after electronic calculators had gone 'mainstream'. The interesting part about it is that it still uses discrete transistors to drive the 14-digit vacuum fluorescent display, as well as in the power supply circuitry. Pocket calculators, by their need for small size, had gone to integrated display driver and power supply circuitry, however, given that desktop calculator designers didn't have to worry too much about space, it was still cheaper at that time to use discrete designs.

The L1428 was obviously intended for business, as it has item count, summing functions, mark up and mark down functions, and two completely independent memories. It also has a square root function, which can take up to 2-3 seconds(!) to perform some operations, the slowness probably due to the fact that the calculations are performed to a full 14 places. The machine calculates results to 14-digits, and decimal point can be set in fixed mode from 0 to 10 places; full floating mode; or a special 'currency' mode where the decimal point is automatically positioned for dollars and cents calculations. A 15th digit at the rightmost end of the integrated VF display has indicators for negative numbers, memory I and memory II registers in use, and item counter in use. Overflow is indicated by a separate discrete LED at the left end of the display tube. The machine is AC powered only, with a simple linear power supply providing the base voltages, with a switching supply generating various voltages needed by the display and single LSI IC which provides the smarts for the machine.


Text and images Copyright ©1997-2011, Rick Bensene.