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Homeland 8109 by Toshiba

Date of introduction:  1977 Display technology:  Fluorescent
New price:   Display size:  8
Size:  5.3" x 3.1" x 0.8"
 135 x 79 x 20 mm3
   
Weight:  3.8 ounces, 108 grams Serial No:  128771
Batteries:  2*AA Date of manufacture:  mth 07 year 1977
AC-Adapter:  BH-310 (100V) Origin of manufacture:  Japan
Precision:  8 Integrated circuits:  TMS1045 (KSΔ7723)
Memories:  1 Displays:  Futaba 9-CT-10
Program steps:   Courtesy of:  Joerg Woerner

Tokyo Shibaura Electric Co., Ltd., better known as Toshiba - the official name since 1978 - introduced early in their history the Homeland brand. 

The Homeland 8109 replaced soon the Homeland 8105 with more or less identical functionality but even lower manufacturing costs. Its sibling Homeland 8009 traded the 4-key Memory for the PI function.

Dismantling the featured Homeland 8109 calculator manufactured in July 1977 in Japan 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 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.

Texas Instruments used the same chip pair in their TI-2550 II and TMS 2550 III calculators.

 



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

Joerg Woerner, February 29, 2004. No reprints without written permission.