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:  36080
Batteries:  BP1A Date of manufacture:  wk 25 year 1975
AC-Adapter:  AC9130, AC9130A Origin of manufacture:  USA
Precision:  13 Integrated circuits:  TMC0501, TMC0521
Memories:  1    
Program steps:   Courtesy of:  Joerg Woerner
Download leaflet:    Download manual:   (US: 7.7M Bytes)

The SR-50A was introduced shortly after the SR-50 to to reduce manufacturing costs. The only advantage compared to early SR-50 calculators is the higher calculating precision. Please find the comparison in the Calculator forensics.

SR-50A_PCB.jpg (86070 Byte)The hardware of the SR-50A uses the TMC0501 Arithmetic Chip with an accuracy of 13 digits and the TMC0521 SCOM (Scanning and Read Only Memory) Chip containing 1k*13 Bits instruction memory and 16*16 digits constants.

Read more about the differences between the SR-50/SR-51 and their successors on the SR-51A page. A low-cost version of the SR-50A was developed but never introduced to the market. Read more about the rare SR-40 prototype.

The appearance of the SR-50A is similar to the later SR-52 and SR-56 calculators. 

With the introduction of the SR-56 in Spring 1976 the hardware of both the SR-50A and SR-51A was redesigned to accommodate the TMC0501 Arithmetic Chip, one (SR-50A) or two TMC0530 SCOM Chips (SR-51A and SR-56) and none (SR-50A and SR-51A) or one TMC0599 Multi-Register Chip (SR-56). Read more about the revised SR-50A.

The SR-50A is featured in the Texas Instruments Deutschland GmbH leaflets ER-1975 and ER-1976 dated 1975 resp. 1976.


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If you have additions to the above article please email:

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