DATAMATH CALCULATOR MUSEUM
Radio Shack EC-425
|Date of introduction:||1974||Display technology:||LED-stick|
|New price:||$79.95||Display size:||8 + 2|
|Size:|| 6.1" x 3.1" x 1.5"
156 x 78 x 38 mm3
|Weight:||9.2 ounces, 262 grams||Serial No:||027759|
|Batteries:||3*AA NiCd||Date of manufacture:||wk 45 year 1974|
|AC-Adapter:||AC9130||Origin of manufacture:||USA|
|Precision:||8 digits||Integrated circuits:||TMS0120|
|Program steps:||Courtesy of:||Joerg Woerner|
EC-425 distributed by Radio Shack (A Tandy corporation company) could be easily
identified as a restyled SR-10. The mold of the housing looks very similar to other restyled
Wedge area calculators like the Montgomery Ward P200.
Dismantling this Radio Shack EC-425 manufactured in October 1974 reveals indeed the printed circuit board (PCB) of the SR-10. It makes use of the TMS0120 single-chip calculator circuit derived from the TMS1802, better known as first "calculator-on-a-chip". The remaining components found inside an early SR-10 are known from the Datamath, too. Two display-drivers each for the segments and digits of the LED-modules and a discrete power converter to generate the three different supplies inside the calculator.
The LED display vary from calculator to calculator, this one uses a Bowmar Optostic.
If you have additions to the above article please email: firstname.lastname@example.org.
© Joerg Woerner, December 5, 2001. No reprints without written permission.