Montgomery Ward P800 aka TXI-8642A

Date of introduction:   Display technology:  LED-modules + lens
New price:   Display size:  8
Size:  5.8" x 3.4" x 1.45"
 147 x 87 x 37 mm3
Weight:  10.1 ounces, 287 grams Serial No:  37B-24919
Batteries:  4*AA NiCd Date of manufacture:  year 1973
AC-Adapter:   Origin of manufacture:  USA
Precision:   Integrated circuits:  TMS0109
Program steps:   Courtesy of:  Joerg Woerner

TXI-8642A_1.jpg (156863 Byte)This boxy calculator does not look like a Texas Instruments product. To identify it, you have to know more about the coding used by Montgomery Ward:

Models starting with

TXI were produced by Texas Instruments
DAN were produced by APF
DNS were produced by National Semiconductors (later Novus)
GLE by Lloyd's

TXI-8642A_PCB.jpg (56146 Byte)If you look deeper into the calculator you'll notice that the P800 is very similar to the TI-2500 Datamath. The circuit diagrams look identical, the integrated circuit is either the TMS0109 borrowed from the TI-3000 or the TMS0103 found in the Bowmar 901B

TXI-8642A_2.jpg (71924 Byte) The keyboard is clearly identified as a standard
Klixon™ product manufactured by Texas Instruments. The colour of the housing, the LED-modules and some other details like the rubber feets are known from the Datamath calculator.

First_TI.jpg (52283 Byte)A similar calculator was sold by Longines Symphonette with the Electronic Calculalator and by Radio Shack with the EC-200.

Don't miss the rare TXI-8661A based on the Exactra 23 calculator.

Datamath™ and Klixon™ are trademarks of Texas Instruments.

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If you have additions to the above article please email:

© Joerg Woerner, December 5, 2001. No reprints without written permission.