DATAMATH CALCULATOR MUSEUM
Texas Instruments SR-51A Version 1
|Date of introduction:||June 1975||Display technology:||LED-stick|
|New price:||$224.95||Display size:||10 + 2|
|Size:|| 5.8" x 3.2" x
147 x 81 x 32 mm3
|Weight:||8.5 ounces, 240 grams||Serial No:||84801|
|Batteries:||BP1A||Date of manufacture:||wk 40 year 1975|
|AC-Adapter:||AC9130, AC9130A||Origin of manufacture:||USA|
|Precision:||13||Integrated circuits:||TMC0501, TMC0522, TMC0523|
|Program steps:||Courtesy of:||Joerg Woerner|
The SR-51A was introduced shortly after the SR-51 to reduce manufacturing costs. You won't notice too much differences to the SR-51, the keyboard layout kept each key on it's place, only the colours changed. You have to open the calculator to understand the differences, the rigid inner keyboard frame of the SR-51 was removed, the LED modules replaced with a LED-stick and bubble-lens magnifier. The appearance of the SR-51A is similar to the later SR-52 and SR-56 calculators.
Mid of 1975 Texas Instruments line of scientific calculators consists of:
SR-16: Lowest end, still in
the huge SR-10 housing
• SR-40: Lower end, never introduced to market
• SR-50A: Volume model, all scientific functions
• SR-51A: High end, includes statistical functions
Recently a different design of the keyboard was discovered. View it here.
Lifetime of the SR-51A was longer than the unfortunate SR-51, next calculater in that line was the SR-51-II.
hardware of the SR-51A uses the TMC0501 Arithmetic
chip with an accuracy of 13 digits and two TMC0522, TMC0523 Scanning Read
Only Memory SCOM's containing 1k*13 instruction memory and 16*16 digits
constants each. The second SCOM chip is mounted in a piggy-back manner on top of
the first chip to use the SR-50A printed circuit board (PCB).
In the last production year the SR-51A got identical hardware to the SR-56. One of the necessary changes were the new SCOM chips TMC0532, TMC0533 instead the former TMC0522, TMC0523.
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© Joerg Woerner, December 5, 2001. No reprints without written permission.