Texas Instruments SR-50A

Date of introduction:  March 1975 Display technology:  LED-stick
New price:  $109.50 Display size:  10 + 2
Size:  5.8" x 3.2" x 1.3"
 147 x 81 x 32 mm3
Weight:  8.5 ounces, 240 grams Serial No:  148641
Batteries:  BP1A Date of manufacture:  wk 21 year 1976
AC-Adapter:  AC9130, AC9130A Origin of manufacture:  USA (LTA)
Precision:  13 Integrated circuits:  TMC0501, TMC0531
Memories:  1    
Program steps:   Courtesy of:  Joerg Woerner

SR-50A_LTA2176_PCB.jpg (319793 Byte)SR-50A_LTA2176_Back.jpg (321585 Byte)The SR-50A was introduced shortly after the SR-50 to to reduce manufacturing costs. Later during production, probably with the introduction of the SR-56, the SR-50A was revised again. The hardware of both the SR-50A and SR-51A was redesigned to accommodate the TMC0501 Arithmetic chip, one (SR-50A) or two Scanning Read Only Memories (SR-51A and SR-56) and none (SR-50A and SR-51A) or one MULTI-REGISTER chip (SR-56).

Basically the same printed circuit board (PCB) was used with different chip populations to manufacturer 3 different calculators priced between US$ 109.50 and US$ 224.95.

Calculator Arithmetic
SCOM's Multi-
SR-50A TMC0501 TMC0531   US$ 109.50
SR-51A TMC0501 TMC0532
  US$ 224.95
SR-56 TMC0501 TMC0537
TMC0599 US$ 179.95


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If you have additions to the above article please email:

Joerg Woerner, September 10, 2008. No reprints without written permission.