Litronix Checkmate (Second Version)

Date of introduction:  1973 Display technology:  LED-modules
New price:   Display size:  8
Size:  5.4" x 3.1" x 1.4"
 138 x 78 x 36 mm3
Weight:  8.0 ounces, 227 grams Serial No:  22300
Batteries:  3*AA NiCd cells Date of manufacture:  mth 06 year 1973
AC-Adapter:   Origin of manufacture:  USA
Precision:  12 Integrated circuits:  LIT-019
Program steps:   Courtesy of:  Joerg Woerner

Litronix, Inc., (Cupertino, CA) was an early light-emitting diode (LED) company that became a leading supplier of displays for handheld calculators and digital watches (e.g. the Hamilton Pulsar line). 

The Checkmate was the first portable electronic calculator developed and manufactured by Litronix  While the original design of the Checkmate was using a Texas Instruments Klixon keypad, did we locate with this second version of the Checkmate a keyboard manufactured by Wild Rover Corp.

The printed circuit board (PCB) of the Checkmate is centered around a LIT-019 calculator circuit, discrete display drivers (the three white ceramic housings are current limiting resistors manufactured by Beckman), and an additional PCB for the LED display.

The display board makes use of three modules with 3 digits, each and one additional discrete LED - most likely all  manufactured by Litronix.

Not sure if you noticed already the unusual lettering of the decimal switch above the [-=] key. Instead the usual 0-2 selection it gives a 2-4 selection. The Checkmate is one of the few portable calculators without floating point operation. 
The label on the back gives an example for calculations with small numbers with the decimal switch set to "4":

.17 : 9 = .0188

The Checkmate was later replaced with the Checkmate 1002 assembled in Malaysia.

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If you have additions to the above article please email:

Joerg Woerner, June 25, 2019. No reprints without written permission.