DATAMATH CALCULATOR MUSEUM
Texas Instruments SR-40 Prototype
|Date of introduction:||Never||Display technology:||LED-stick|
|New price:||Display size:||10 + 2|
|Size:|| 5.8" x 3.2" x
147 x 81 x 32 mm3
|Weight:||8.1 ounces, 231 grams||Serial No:||001P|
|Batteries:||BP1A||Date of manufacture:||wk 22 year 1975|
|AC-Adapter:||AC9130||Origin of manufacture:||USA|
|Program steps:||Courtesy of:||Joerg Woerner|
At first glance matches this rare SR-40 perfectly with the successful scientific calculators SR-50A and SR-51A introduced in March resp. June, 1975.
But this SR-40 was never released to the market, the pictured
calculator is a rare prototype with the impressive serial number 001P.
Nevertheless do we all know the final SR-40 - a
sibling of the best selling TI-30
calculator introduced June 13, 1976.
Dismantling the SR-40 001P explains immediately the story behind this project:
The housing is identical to the SR-50A and uses still the
Fellow collector Miroslav Krob discovered in November 2009 the real sensation of the SR-40 Prototype: Please look carefully at the keyboard, there are two keys with parentheses! The first ones on a calculator from Texas Instruments! Thanks, Miroslav!
The datecode on the TMS1111 and the internal construction allows a precise placement of the SR-40 P001 in the history of Texas Instruments:
|January 1974||SR-50||First scientific calculator including trigonometric functions based on the TMC0501 building blocks.|
|October 1974||SR-16||First use of the TMS1000 single-chip calculator in the old SR-11 housing.|
|March 1975||SR-50A||Cost reduction of the original SR-50. Main differences are the housing and arrangement of the printed circuit boards.|
|June 1975||SR-40||Sandwiched between the SR-50A and SR-16 II. Expensive battery pack and colorful keyboard from the big brother combined with the poor algorithm of the smaller brother. Not the best choice !|
|August 1975||SR-16 II||Cost reduction of the original SR-16, makes use of the SR-50A housing, standard batteries and cheap black keys.|
|October 1975||TI-2550 II||Introduction of the BP2, a rechargeable battery pack with only 2 AA-cells instead the 3 AA-cells of the BP1A.|
Interested in failed calculators? Don't miss the first TI-88 scheduled for release in 1982.
Running Mike Sebastian's "Calculator forensics" gives an unacceptable bad result of 10.271817 instead the expected value close to 9.0000. This places the SR-40 in the league of calculators like the Canon F-6 (12.199423) and Rockwell 61R (10.4328).
All other Texas Instruments calculators fit between the TI-35 PLUS (8.99999798135) and TI-45 (9.177087103).
+++ UPDATE: Fellow collector Marie Collas discovers a
SR-40 Prototype with a "real" serial number 0f
0000030 in Mexico. +++
If you have additions to the above article please email: firstname.lastname@example.org.
© Joerg Woerner, January 18, 2003. No reprints without written permission.