DATAMATH CALCULATOR MUSEUM
|Date of introduction:||1979||Display technology:||Fluorescent|
|New price:||DM 25.00||Display size:||8|
|Size:|| 5.6" x 3.0" x 0.8"
142 x 75 x 20 mm3
|Weight:||3.9 ounces, 110 grams||Serial No:||C 17661|
|Batteries:||2*AA||Date of manufacture:||mth 01 year 1979|
|AC-Adapter:|| BH-115 (110V) or
|Origin of manufacture:||Taiwan|
|Precision:||8||Integrated circuits:||TMS1045 (MT 8001)|
|Program steps:||Courtesy of:||Joerg Woerner|
This Toshiba BC-8111B "Basic with Memory" calculator followed the otherwise identical BC-8111 and shares its internal design with the BC-8018B "Basic" and BC-8112SL "Enhanced Basic" calculators. The rather unusual approach to use identical electronics for three calculators with a quite different feature set was made possible with Texas Instruments' introduction of the cost-effective TMS1040 Product Family based on the TMS1070 "computer-on-a-chip" introduced in 1974 with the original TMS1000. But we have to credit Canon releasing the full potential of the TMS1040 with its "Almost Scientific" F-31 calculator in 1977.
Comparing the functionality of the three Toshiba calculators and the Canon F-31 demonstrates the bandwidth of products made possible with the TMS1045 single-chip calculator circuit:
the featured BC-8111B calculator manufactured in January 1980 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
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 VPP 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.
Looking closer onto the PCB you'll notice two diodes labeled D4 and D5 and placed somehow between the TMS1045 and the keyboard assembly - at first glance an unusual approach. Preparing our DCM-50A Platform to allow the Characterization of Single-Chip Calculator Circuits of the TMS1040 Family, we reverse-engineered the BC-8111B calculator and understood that Texas Instruments started to add with the TMS1040 a "virtual" 5th Keyboard Input line by using two additional diodes emulating the 5 K Inputs of the TMC0980 Family. While the TMS0100 single-chip calculator circuit introduced the concept of an 11x4 keyboard matrix scanned with the 11 Digit Outputs and 4 Keyboard Inputs, would the reduction to just 9 Digit Outputs of the TMS1040 allow for only 9x4 keys and switches, in some calculator applications like the Canon F-31 a show-stopper. Adding an extra "virtual" Keyboard Input allows consequently for a 9x5 keyboard matrix and this BC-8111B arranges its 24 keys within a 9x4 grid.
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© Joerg Woerner, July 3, 2002. No reprints without written permission.