Exactra 20 by Texas Instruments 

Date of introduction:  April 15, 1974 Display technology:  LED-stick
New price:  $39.88 Display size:  6
Size:  5.1" x 2.9" x 1.3"
 130 x 74 x 34 mm3
Weight:  5.1 ounces, 144 grams Serial No:  2000033697
Batteries:  3*AA  Date of manufacture:  unknown
AC-Adapter:   Origin of manufacture:  USA
Precision:   Integrated circuits:  TMS0135
Program steps:   Courtesy of:  Joerg Woerner
    Download manual:   (US: 1.6 MByte)

EX20_DISP.jpg (39530 Byte)The Exactra 20 added to the Exactra 19 a sliding switch to use either fix point or floating point notation on the small 6-digit display. Another enhancement could be found in the keyboard, instead of very small keys you could find on the Exactra 20 larger ones with molded printing on them. The three sibblings Exactra 21, Exactra 22 and Exactra 23 sport a standard 8-digit display.

EX20_PCB.jpg (68740 Byte)The printed circuit board (PCB) of the Exactra 20 makes use of the TMS0135 single-chip calculator circuit and a tiny display driver. The remaining parts form a small power-converter to use the 3 AA-sized batteries instead a 9V battery block. Instead of the single-sided PCB of the Exactra 19 this one uses a more expensive double-sided board.

Compare this calculator with the European TI-2000.


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If you have additions to the above article please email:

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