Texas Instruments SR-50 (The Netherlands)

Date of introduction:  January 15, 1974 Display technology:  LED modules + lens
New price:  DM 520.00 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:  9239265
Batteries:  BP1 Date of manufacture:  wk 22 year 1975
AC-Adapter:  AC9200 Origin of manufacture:  The Netherlands
Precision:  13 Integrated circuits:  TMC0501, TMC0521
Logic:  Sum-of-Products    
Memories:  1    
Program steps:   Courtesy of:  Joerg Woerner

Texas Instruments manufactured its successful SR-50 "slide rule" calculator for the European market in their Almelo facility in Holland. The US-built and European-built products differed only in the label on the backside of the calculators, their printed circuit boards (PCB's) and Integrated Circuits (IC's) were 100% identical.

The featured SR-50 calculator was manufactured in May 1975, a very interesting detail:

Its successor SR-50A was introduced already in March 1975 in the USA.
We considered briefly the phase-out of the European SR-50 in or around
   December 1974, find more details here.

With the TMS0500 Building Blocks Texas Instruments created a novel architecture for scalable scientific calculators. The architecture used minimum a 2 chip design with the TMC0501 Arithmetic Chip and the TMC0520 SCOM (Scanning and Read Only Memory) Chip but was expandable to a maximum of 8 SCOMs, additional RAM as program memory for programmable calculators, additional RAM for general purpose registers and even a chip driving a printerr. Most scientific and programmable calculators from Texas Instruments between the years 1974 and 1982 like the SR-51, SR-60A and TI-59 use these chips. Please find all known calculators using the TMC0501 architecture here. Don't miss the odd TI-5230 desktop calculator.

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If you have additions to the above article please email:

Joerg Woerner, November 1, 2011. No reprints without written permission.