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Western Auto Citation aka M4988 (Version 2)

Date of introduction:  April 1977 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:  0027812
Batteries:  9V  Date of manufacture:  wk 15 year 1977
AC-Adapter:  AC9180 Origin of manufacture:  USA
Precision:  8 Integrated circuits:  TMS0974/ZA0355
Memories:      
Program steps:   Courtesy of:  Joerg Woerner

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 1577 LTA and manufactured in April 1977 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.

With the discontinuation of the TI-1200 family in 1977, Western Auto consequently replaced the M4988 "Citation" calculators and its siblings M4986 and M4987 with products based on the TI-1000 family. While the backside of the revised "Citation" calculator is missing any reference to the previous M4988 designation, sports the sales box a part number 66-4988-3, obviously a reference to the original naming scheme. Please find in the table below a cross reference between Western Auto's 1976/1977 and 1977/1878 calculator offerings:

Western Auto
1976/1977
Texas Instruments
1976/1977
Western Auto
1977/1978
Texas Instruments
1977/1978
Citation
M4986
TI-1200 Citation
66-4986-7
TI-1000
Citation
M4987
TI-1250 Citation
66-4987-5
TI-1025
Citation
M4988
TI-1270 Citation
66-4988-3
TI-1050

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

Joerg Woerner, July 5, 2021. No reprints without written permission.