DATAMATH CALCULATOR MUSEUM
Radio Shack EC-300
|Date of introduction:||1974||Display technology:||LED-modules + lens|
|New price:||$114.95||Display size:||8|
|Size:|| 5.8" x 3.5" x 1.9"
148 x 88 x 48 mm3
|Weight:||6.7 ounces, 191 grams||Serial No:||300-17186|
|Batteries:||4*AA||Date of manufacture:||wk 20 year 1974|
|AC-Adapter:||Origin of manufacture:||USA|
|Precision:||8||Integrated circuits:||WD LC1552B|
|Program steps:||Courtesy of:||Mike Sebastian|
This EC-300 does not look like a Texas Instruments product and made a great design evolution compared to the earlier EC-200.
we dismantle this calculator, one question will immediately arise: Which company
manufactured this EC-300? Searching the single-chip calculator circuit reveals a
great surprise: The huge IC carries the logo of Western
Digital and is one step ahead the TI chips of that era:
The TI-2550 with similar complexity (%-key and 4-key memory) was introduced later. Maybe TI had a delay in the development of the TMS0601, the direct counterpart of the Western Digital LC1552 used in the EC-300 and the Montgomery Ward P8P. Interesting note: Bowmar used with the MX55 the same chip for a calculator without memory. The keyboard of the calculator is a mixture of the TI-1500 keys and the grid of the Datamath.
In 2001 we were indeed not sure who manufactured the EC-300. The owner of this wonderful EC-300, Mike Sebastian noticed a small indicator in the manual of his calculator:
We know this address! Just compare it with the well known Texas Instruments consumer service facilities of the year 1974 and found on a SR-10:
Texas Instruments Service Facility
Nevertheless, this is the Service Center - maybe TI offered just the repair service for Radio Shack. In 2003 we finally found the answer when we explored the EC-1000, a desktop calculator matching the design line of this EC-300. This calculator looks and feels like a TI product but carries no TI logo inside. The secret of both calculators is a magic number on the printed circuit board (PCB): 13-04-709-479 - read more here.
The battery compartment of the EC-300 sports a small sliding switch to select between "RECHARGABLE NI-CD BATTERIES" and "ALL OTHER BATTERIES". This switch prevents the AC-Adapter from providing a charge to the batteries if the switch is set to "ALL OTHER BATTERIES".
Datamath™ is a trademark of Texas Instruments.
Known serial numbers:
A2 300-02184, A2 300-17186, A2 300-20385
If you have additions to the above article please email: firstname.lastname@example.org.
© Joerg Woerner, December 5, 2001. No reprints without written permission.