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
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.

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If you have additions to the above article please email:

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