DATAMATH CALCULATOR MUSEUM
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DATAMATH CALCULATOR MUSEUM |
Western Auto electronic Wizard aka M4987 (Version 1)
| Date of introduction: | June 1975 | Display technology: | LED-stick |
| New price: | Display size: | 8 | |
| Size: | 5.5" x 2.8" x 1.4" 138 x 70 x 35 mm3 |
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| Weight: | 3.9 ounces, 110 grams | Serial No: | 00013705 |
| Batteries: | 9V | Date of manufacture: | wk 37 year 1975 |
| AC-Adapter: | AC9180 | Origin of manufacture: | USA |
| Precision: | 8 | Integrated circuits: | TMS0952 |
| Memories: | 1 | ||
| Program steps: | Courtesy of: | Peter Muckermann |
Texas
Instruments introduced the TI-1200 in March 1975 and followed within just a few
months with the TI-1250 featuring a 4-key Memory and a [CS] or [+/-] key. The
TI-1200/TI-1250 family developed into one of TI's most successful
calculator series, selling millions and millions units not only under its own name
plate but branded for different companies like HEMA, Koh-I-Noor Hardtmuth, True Value Hardware Stores,
Zayre Corporation and Western Auto.
The Western Auto versions of the TI-1200/TI-1250 stood out of the crowd with their "woody" design but were other than the missing TI logo identical to them and followed the various phases of cost-optimization. Most common names for the TI-1250 based Western Auto calculators are "electronic Wizard" or "M4987", while the TI-1200 based version is known as M4986. In or around March 1976 the name was changed to "Citation".
Dismantling the featured TI-1250 with
Date code 3775 LTA and manufactured in
September 1975
in Lubbock, Texas reveals a very efficient and cost-optimized design with a
single-sided printed circuit board (PCB) centered
around a TMS0952 single-chip
calculator circuit based
on the TMS1000, the World's first Microcomputer.
The original design of the TI-1200/TI-1250 was only manufactured for a few months, Texas Instruments changed the PCB slightly to accommodate four additional 330Ω resistors to pull down the four keymatrix input lines of the TMS0952 Chip to VDD.
Learn
more about the evolution of the TI-1250 between
June 1975 and its discontinuation in 1977.
The M4987 mirrors the design phases of the TI-1250:
| Version | PCB Type |
Date codes From |
Date codes To |
Chip Designation |
Chip Package |
Display | Discrete Components |
| M4987 V1 | Type 1 | 2275 LTA | 3375 LTA | TMS0952NL Δ, CΔ |
DIP28 | 9-digits | 4 Res, 1 Cap |
| M4987 V2 | Type 2 | 3475 LTA | 0876 LTA | TMS0952NL Δ, CΔ, KESΔ |
DIP28 | 9-digits | 8 Res, 1 Cap |
| M4987 V3 | Type 2 | 1276 LTA | 1277 LTA | TMS0972NL AP, ASP |
DIP28 | 8-digits | 1 Jumper Wire |
| M4987 V4 | Type 3 | 1577 LTA | 1877 LTA | TMS0972NL ASP |
SPDIP28 | 8-digits |
Learn more about the different
Product Labels used with the TI-1250
- here at the Datamath Calculator Museum we classify the featured M4987 as
Hardware Version 1, PCB Type 1 and Product Label Style 3, Western Auto.
If you have additions to the above article please email: joerg@datamath.org.
© Joerg Woerner, January 4, 2002. No reprints without written permission.