Toshiba BC-8018B (Version 2)

The internals of the Toshiba BC-8018B calculator switched soon from a Sharp LI2017 single-chip calculator circuit to a Texas Instruments TMS1045, a member of the TMS1040 Product Family introduced in 1976 and based on the TMS1070 "computer-on-a-chip" introduced in 1974 with the original TMS1000. While the Sharp LI2017 uses two separate [C] and [CE] keys, used the TMS1045 in this application a combined [C/CE] key and the users received the [PI] key instead.

Learn more about the electronics of this BC-8018B (Version 2) used with the BC-8111B and BC-8112SL, too.

Dismantling the featured BC-8018B calculator manufactured in August 1978 by Zeny Corporation in Taiwan reveals a very cost effective design using a single-sided printed circuit board (PCB) centered around a TMS1045 single-chip calculator circuit connected to a 9-digit Vacuum Fluorescent Display (VFD), a keyboard assembly and powered by 2 AA-sized alkaline batteries.

While the earlier TMS1070 can directly interface with low-voltage VFD up to 35 Volts does it still need external resistors and a zener diode to bias the anodes and grids of the display with respect to the filament. The TMS1040 added an extra V_PP pin to connect a negative 30 Volts bias voltage for its modified output drivers. With the TMS1070 featuring 11 R Outputs for the Digits, 8 O Outputs for the Segments and 4 K Inputs for the Keyboard, reduced the TMS1040 the number of R Outputs to 9, consequently are all known TMS1040 calculator designs using a 9-digit VF Display.

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© Joerg Woerner, December 11, 2002. No reprints without written permission.