DATAMATH CALCULATOR MUSEUM
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DATAMATH CALCULATOR MUSEUM |
Texas Instruments SR-51 (Clear-Case Prototype)
| Date of introduction: | (January 1975) | Display technology: | LED modules + lens |
| New price: | $224.95 | 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: | 45499 |
| Batteries: | BP1 | Date of manufacture: | wk 46 year 1974 |
| AC-Adapter: | AC9200 | Origin of manufacture: | USA |
| Precision: | 13 | Integrated circuits: | TMC0501, TMC0522, |
| Logic: | Sum-of-Products | Displays: | |
| Memories: | 3 | ||
| Program steps: | Courtesy of: | Joerg Woerner | |
| Download manuals: | 
(US: 2.0M Bytes)
(US: 12.4M Bytes) |
With
the SR-51 Texas Instruments started a series of scientific calculators that
added statistical functions and conversions to the "usual functions".
You'll find similar performance and keyboard layout in the line SR-51 -> SR-51A
-> SR-51-II -> TI-55
-> TI-55-II -> TI-55-III.
But none of them was engineered as perfect as the
SR-51. It was built like a tank to survive decades of use as its close relative SR-50.
Compared to the previous models the SR-51 got a keyboard design with white, grey,
yellow and orange keys and gave an outlook to later TI calculators.
This SR-51 Clear-Case Prototype was most likely manufactured in November 1974 and is a strange hybrid sporting:
| • A rather high serial number SR-51 0045499 • A very early SCOM chip manufactured in October 1974 • A keyboard with the bold lettering of an early SR-51 but the slanted line striking through the EE text of the later SR-51 |
The
SR-51 was the first calculator in TI's line using stacked Integrated Circuits (Piggy
Back ICs). Please note on the right picture the two SCOM (Scanning and Read Only
Memory) Chips.
The
SR-51 was introduced in January 1975, nevertheless the firmware of the
calculator was released already three month earlier. Please notice the Date
code 7444 printed on the TMC0523 SCOM
Chip
storing part of the program of the calculator.
Recently we discovered an SR-51E
(Engineering Sample) with a Date code 7434 on its TMC0523 SCOM Chip, adding
another 10 weeks between software release and market introduction...
Interesting to know, this calculator almost works with the PC-100
"Printer Cradle" developed for the SR-52 and
SR-56. Learn more about
Printing with the SR-51 / SR-51A.
If you have additions to the above article please email: joerg@datamath.org.
© Joerg Woerner, November 18, 2018. No reprints without written permission.