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Additional Pictures 

 

This Radio Shack EC-425 was manufactured in August 1974 by
Texas Instruments  (Date code 314 wk 31 yr 1974.

The double-sided printed circuit board (PCB) of the Radio Shack EC-425
is centered around a TMS0120 single-chip calculator circuit.

Close-up view of the TMS0120 (TMS0720) single-chip calculator circuit.

Close-up view of the SN75493 Segment Driver.

Close-up view of the SN27423 Digit Driver.

Close-up view of the Bowmar Optostic 175 Twelve-Digit Calculator Seven-Segment display.


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If you have additions to the above article please email: joerg@datamath.org.

Joerg Woerner, May 11, 2011. No reprints without written permission.