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
1.3" 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 |
Precision: | 10 | Integrated circuits: | TMS1111 |
Memories: | 1 | ||
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
BP1A
battery pack. |
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 date code on the TMS1111 and the internal construction allows a precise placement of the SR-40 P001 in the history of Texas Instruments:
Timeline | Calculator | Comment | Link |
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 discovered a
SR-40 Prototype with a "real" serial number
of
0000030 in Mexico. +++
If you have additions to the above article please email: joerg@datamath.org.
© Joerg Woerner, January 18, 2003. No reprints without written permission.