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Western Auto Citation aka 66-4988-3

Date of introduction:  1977 Display technology:  Fluorescent
New price:  $14.99 Display size:  8
Size:  5.4" x 2.8" x 1.3"
 138 x 72 x 32 mm3
   
Weight:  3.5 ounces, 98 grams Serial No:  
Batteries:  9V  Date of manufacture:  wk 16 year 1978
AC-Adapter:  AC9180 Origin of manufacture:  El Salvador
Precision:  8 Integrated circuits:  TMC0921
Memories:  1    
Program steps:   Courtesy of:  Joerg Woerner

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

The elegant design of the TI-1270 based M4988 "Citation" calculator was continued with its successor and further enhanced with a two-tone keyplate. Other than that are the "Citation" and TI-1050 identical, the back side of the calculators tells you even its manufacturer Texas Instruments.

Dismantling the featured 66-4988-3 with Date code 1678 and manufactured in April 1978 in El Salvador reveals a very efficient and cost-optimized design with a small double-sided printed circuit board (PCB) centered around a TMC0921 single-chip calculator circuit and powered by a 9V battery.

The TMC0920 calculator chips are minimalistic designs sporting just 512*9 Bits of ROM (Read-Only Memory) and 200 Bits of SAM (Serial-Access Memory) organized in 5 Registers of 10 Digits, each but feature both an integrated charge pump driver to generate the high voltage (around -22V) for the Anodes and Grids of the VF-Display and integrated drivers for the Filament (heater) of it. Additional cost savings could be achieved by replacing a conventional [ON-OFF] switch with a simple push-button [ON] key.

Western Auto Supply Company ceased end of 1978 distributing "Citation" calculators manufactured by Texas Instruments, just 5 years after their journey began with the M4995 "electronic Wizard".



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

Joerg Woerner, December 29, 2002. No reprints without written permission.