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DATAMATH CALCULATOR MUSEUM

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 V_DD. 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.

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