DATAMATH CALCULATOR MUSEUM
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DATAMATH CALCULATOR MUSEUM |
Texas Instruments SR-50
| Date of introduction: | January 15, 1974 | Display technology: | LED modules + lens |
| New price: | $169.95, DM 520.00 | Display size: | 10 + 2 |
| Size: | 5.8" x 3.2" x
1.3" 147 x 81 x 32 mm3 |
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| Weight: | 8.5 ounces, 240 grams | Serial No: | 211917 |
| Batteries: | BP1 | Date of manufacture: | wk 42 year 1974 |
| AC-Adapter: | AC9200 | Origin of manufacture: | USA |
| Precision: | 13 | Integrated circuits: | TMC0501, TMC0521 |
| Memories: | 1 | Displays: | DIS288 (14*DIS279) |
| Program steps: | Courtesy of: | Joerg Woerner | |
| Download leaflets: |
US: 2.2M Bytes)
DE: 1.9M Bytes) |
Download manual: |
(US: 5.6M Bytes) |
The
wonderful electronic slide rule SR-50 marked a milestone in the history of
calculators manufactured by Texas Instruments. It added trigonometric and
hyperbolic functions, the logarithms and their inverses to the scientific
functions of the SR-10, SR-11
and SR-16 line of calculators. The calculator was placed
with big success against Hewlett-Packard's HP-35 and produced in high quantity.
The internal construction was very rigid compared with other models. To reduce
manufacturing costs and to give a similar appearance to the SR-52
and SR-56 calculators the SR-50 was replaced within 18
month with the SR-50A. Don't miss the rare SR-51.
On a first view the twins SR-50 and SR-50A look similar, but
if you use them you'll feel the differences! If you search for the best SR-50,
choose a model produced later than July 1974. Engineers at Texas Instruments
changed the calculation algorithms and achieved a higher precision. Please find the comparison in the
Calculator
forensics.
With the TMC0500 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 printer. 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. Don't miss the SR-50
manufactured for Dismac Industrial S.A. in Brazil changing the layout of the
aluminum bezel.
Masaki Takada donated some wonderful pictures and this gives us the opportunity to view the inside of the SR-50.
| Engineers use the clear case during the development of a product to check if the electronic and mechanical components fit neatly into the housing. |  |
| The side view gives you an impression of the upper and lower case shell and the printed circuit boards inside. |  |
| The bottom view gives you (from upper right to lower left) the opening of the rechargeable batteries, the huge calculator chips (TMC0501, TMC0521) and the power supply circuit. |  |
| The display frame covers the upper row of the keys and the two switches neatly. This gives you a very valuable design compared to e.g. the TI-30. |  |
| This wonderful pictures gives you an imagination of the curved lens above the red display. A perfect calculator! |  |
If you have additions to the above article please email: joerg@datamath.org.
© Joerg Woerner, December 5, 2001. No reprints without written permission.