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Western Auto electronic Wizard aka M4986 (Version 1)

Date of introduction:  May 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
   
Weight:  3.9 ounces, 110 grams Serial No:  0006504
Batteries:  9V  Date of manufacture:  wk 29 year 1975
AC-Adapter:  AC9180 Origin of manufacture:  USA
Precision:  8 Integrated circuits:  TMS0952
Memories:      
Program steps:   Courtesy of:  Joerg Woerner

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-1200 based Western Auto calculators are "electronic Wizard" or "M4986", while the TI-1250 based version is known as M4987. In or around March 1976 the name was changed to "Citation".

Dismantling the featured M4986 with Date code 2975 LTA and manufactured in July 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. The appearance and functionality of the revised M4986 did not change.

Learn more about the evolution of the TI-1200 between March 1975 and its discontinuation in 1977. The M4986 mirrors the design phases of the TI-1200:

Version PCB
Type
Date codes
From
Date codes
To
Chip
Designation
Chip
Package
Display Discrete
Components
M4986 V1 Type 1 2275 LTA 3375 LTA TMS0952NL
Δ, CΔ
DIP28 9-digits 4 Res, 1 Cap
M4986 V2 Type 2 3475 LTA 0876 LTA TMS0952NL
Δ, CΔ, KESΔ
DIP28 9-digits 8 Res, 1 Cap
M4986 V3 Type 2 1276 LTA 1277 LTA TMS0972NL
AP, ASP
DIP28 8-digits 1 Jumper Wire
M4986 V4 Type 3 1577 LTA 1877 LTA TMS0972NL
ASP
SPDIP28 8-digits  

Learn more about the different Product Labels used with the TI-1200 - here at the Datamath Calculator Museum we classify the featured M4986 as Hardware Version 1, PCB Type 1 and Product Label Style 3, Western Auto.

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

Joerg Woerner, December 5, 2001. No reprints without written permission.