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Texas Instruments SR-51 (late model)

Date of introduction:  January, 1975 Display technology:  LED modules + lens
New price:  $224.95 Display size:  10 + 2
Size:  5.8" x 3.2" x 1.3"    
Weight:  9 ounces Serial No:  53539
Batteries:  BP1 Date of manufacture:  wk 13 year 1975
AC-Adapter:  AC9200 Origin of manufacture:  USA
Precision:  13 Integrated circuits:  TMC0501, TMC0522, TMC0523
Memories:  3    
Program steps:   Courtesy of:  Joerg Woerner

With the SR-51 Texas Instruments started a series of scientific calculators that added statistical functions and conversions to the "usual functions". You'll find similar performance and keyboard layout in the line SR-51 -> SR-51A -> SR-51-II -> TI-55 -> TI-55-II -> TI-55-III. But none of them was done as perfect as the SR-51. It was designed to stay decades as the close relative SR-50. Compared to the previous models the SR-51 got a keyboard design with white, grey, yellow and orange keys and gave an outlook to later TI calculators.

To reduce manufacturing costs and to give a similar appearence to the SR-52 and SR-56 calculators the SR-51 was replaced within few month with the SR-51A. The calculator on the left was produced March 1975, earlier models used bold letters for the second functions. Compare it here.

sr-51_PCB.jpg (79329 Byte)The SR-51 was the first calculator in TI's line using stacked Integrated Circuits (Piggy Back IC's). Please note on the right picture the two SCOM circuits. 

Funny to know, that this calculator works with the PC-100 "Printer Craddle" from the SR-52 and SR-56.


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

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