![]() |
DATAMATH CALCULATOR MUSEUM |
Texas Instruments SR-20
Date of introduction: | Sept.11, 1973 | Display technology: | Panaplex II |
New price: | $179.95 | Display size: | 10+2 |
Size: | 9.1" x 6.5" x 2.6" 232 x 165 x 67 mm3 |
||
Weight: | 31.0 ounces, 881 grams | Serial No: | 200047163 |
Batteries: | Date of manufacture: | wk 44 year 1973 | |
AC-Adapter: | 120 V | Origin of manufacture: | USA |
Precision: | Integrated circuits: | TMS0202, TMS0304 | |
Memories: | |||
Program steps: | Courtesy of: | Joerg Woerner | |
Download manual: | ![]() |
The
SR-20 is one of the few scientific desktop calculators manufactured by Texas
Instruments. In a housing with the size of a TI-3500
but the extreme wedge shape of the SR-10
you find some useful scientific functions but no memory.
The displays used in the SR-20 are Panaplex II
devices. Produced by Burroughs they are long-life, cold-cathode, glow-discharge
display panels. Keep your fingers away, normal voltage is about 150 Volts. With their
orange glow they give a perfect readability even in bright ambient situations.
A similar calculator performing conversions between octal,
decimal and hexadecimal number bases was the SR-22.
Due to the limited digit capabilities of the
TMS0100 calculator-on-a-chip series, Texas
Instruments developed the
TMS0200 Chipset
for 12-digit desktop calculators. This TI-4000 introduced in 1973 marks the
first application based on the TMS0200
Building Blocks and makes use of the TMS0200
Data Chip named TMS0201 and the TMS0300 ROM
Chip named TMS0301 accordingly. Later designs added either the
TMS0220 Printer Chip (TI-500), or the
TMC0400 ROM/Register Chip (SR-22), or both of them (TI-620).
Texas Instruments made the TMS0200 Building Blocks available to third parties, don't miss the Canon L121F.
It took about 10 years before the next (non-programmable) scientific desktop calculator manufactured by TI was introduced. Do you know it? View it here.
Some parts of the calculator housing and the display could be found in an industrial product, view the 5TI PLC programmer.
If you have additions to the above article please email: joerg@datamath.org.
© Joerg Woerner, December 5, 2001. No reprints without written permission.