DATAMATH CALCULATOR MUSEUM
Western Auto Citation aka 66-4987-5
|Date of introduction:||1977||Display technology:||Fluorescent|
|New price:||Display size:||8|
|Size:|| 5.4" x 2.8" x
138 x 72 x 32 mm3
|Weight:||3.5 ounces, 98 grams||Serial No:|
|Batteries:||9V||Date of manufacture:||wk 41 year 1977|
|AC-Adapter:||AC9180||Origin of manufacture:||USA (MTA)|
|Program steps:||Courtesy of:||Joćo Oliveira|
|Download manual:||(US: 3.3M Bytes)|
With the discontinuation of the TI-1200 family in 1977, Western Auto consequently replaced the M4987 "Citation" calculators and its siblings M4986 and M4988 with products based on the TI-1000 family. While the backside of the revised "Citation" calculator is missing any reference to the previous M4987 designation, sports the sales box a part number 66-4987-5, 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:
eye-catching "woody" design of the TI-1250 based M4987 "Citation" calculator was
continued with its successor. Other than that are the "Citation" and TI-1025 identical, the back
side of the calculators
tells you even its manufacturer Texas Instruments.
Dismantling the featured 66-4987-5 with Date code 4177 MTA and manufactured in October 1977 in Midland, Texas reveals a very efficient and cost-optimized design with a small double-sided printed circuit board (PCB) centered around a TMC0923 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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© Joerg Woerner, January 4, 2002. No reprints without written permission.