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DATAMATH CALCULATOR MUSEUM

Western Auto Citation aka M4988 (Version 1)

Date of introduction:	May 1976	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:	0007284
Batteries:	9V	Date of manufacture:	wk 41 year 1976
AC-Adapter:	AC9180	Origin of manufacture:	USA
Precision:	8	Integrated circuits:	TMS0974/ZA0355
Memories:
Program steps:		Courtesy of:	Peter Muckermann († April 21, 2021)

Western Auto extended in May 1976 its portfolio of portable electronic calculators with the M4988 aka "Citation" based on Texas Instruments' TI-1270 to complement the M4986 and M4987. Main differences between the M4988 and the TI-1270 are the color of the keyplate and the missing TI logo.

Dismantling the featured M4988 with Date code 4176 LTA and manufactured in October 1976 in Lubbock, Texas reveals a very efficient and cost-optimized design with a single-sided printed circuit board (PCB) centered around a TMS0974 single-chip calculator circuit based on the TMS1000, the World's first Microcomputer.

The final step of cost reduction of the of the M4988 was introduced just a few months before its discontinuation and included a smaller encapsulation of the TMS0974 Chip. While the original design was using a 0.6” wide 28-pin DIP (Plastic Dual In-line Package with a 0.1” / 2.54 mm lead pitch) encapsulation, switched the final design to a 0.4” wide 28-pin SPDIP (Shrink Plastic Dual In-line Package with a 0.07” / 1.778 mm lead pitch) encapsulation.

Learn more about the evolution of the TI-1270 between April 1976 and its discontinuation in 1977.

Learn more about the different Product Labels used with the TI-1250 - here at the Datamath Calculator Museum we classify the featured M4988 as Hardware Version 1, PCB Type 2 and Product Label Style 3, Beige, Western Auto.

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