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Toshiba BC-1015

Date of introduction:  1979 Display technology:  Fluorescent
New price:  DM 75.00 Display size:  10
Size:  6.4" x 6.1" x 1.80"
 162 x 155 x 46 mm3
   
Weight:  10.8 ounces, 306 grams Serial No:  10907
Batteries:  2*D Alkaline Date of manufacture:  mth 04 year 1979
AC-Adapter:  BH-126 (110V) or
 BH-127 (220V)
Origin of manufacture:  Taiwan
Precision:  10 Integrated circuits:  TMC1073 (MSL 7901)
Memories:  1 Displays:  Futaba 11-BT-16A
Program steps:   Courtesy of:  Joerg Woerner

Toshiba introduced in 1979 with this BC-1015 a very capable "Small Desktop" calculator still sporting adding machine style [+=] and [-=] keys but featuring enhanced functions like Delta-Percentage and Gross Profit Margin calculations and even an Item Counter. If the keyboard layout looks somehow familiar to you, don't miss the TI-5100 introduced four years earlier.

Dismantling the featured Toshiba BC-1015 manufactured in April 1979 by Zeny Corporation in Taiwan reveals a very clean design based on a single-sided printed circuit board (PCB) for the main electronics connected to the keyboard and powered by two large D-sized, disposable Alkaline batteries.

The Main-PCB is centered around a TMC1073 single-chip calculator circuit, a member of the TMS1000 Microcomputer family introduced in October 1974 with the SR-16 calculator. While the TMS1000 design was mainly intended for designs using power-hungry LED displays with external display drivers, uses the TMS1070 redesigned output drivers for the 11 R-Outputs (Display Scan) and 8 O-Outputs (Segments) that can withstand voltages up to -35 Volts and hence allows direct operation of low-voltage Vacuum Fluorescent Displays (VFDs).

The BC-1015 makes fully use of the TMS1070 design and we could identify on the Main-PCB both the voltage converter to generate a -30 Volts supply for the Futaba 11-BT-16A VFD and the external "pull down" resistors for the R- and O-Outputs. A very similar design was introduced already with the TI-2550 II, the first application of the TMS1070 chip.

If you compare this BC-1015 with the TI-5100 sporting an identical TMC1073 chip carefully, you'll notice differences with both the number of keys and the lettering on them and you might ask yourself: Are there even more features and functions available with the TMC1073 chip that neither of the two calculators is using? And how do the control a 10-segment display with just 8 O-Outputs? Hint: Only 9 segments are used with the BC-1015. Learn more about Characterization of Single-Chip Calculator Circuits with the DCM-50A Platform

Don't miss the LC-1016 introduced in the same timeframe.

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

Joerg Woerner, May 22, 2002. No reprints without written permission.