Exactra 21 by Texas Instruments 

Date of introduction:  March 1974 Display technology:  LED-stick
New price:   Display size:  8
Size:  5.1" x 2.9" x 1.3"
 130 x 74 x 34 mm3
Weight:  5.1 ounces, 144 grams Serial No:  2100297344
Batteries:  3*AA  Date of manufacture:  wk 09 yr 1975
AC-Adapter:   Origin of manufacture:  USA
Precision:   Integrated circuits:  TMS0803
Program steps:   Courtesy of:  Joerg Woerner

EX21-1_DISP.jpg (42470 Byte)The Exactra 21 with it's brown keyplate uses a 8-digit display and similar electronics to the TI-1500 and TI-2500-II calculators. All three were available in the same period, this gives you an idea of the positioning in the marketing of each calculator:

Datamath solid and well established since 1972
TI-1500 modern and stylish
Exactra 21 young and cheap

Even this cheap looking keyboard relies on the proven Klixon keyboard technology.

EX21-1_PCB.jpg (66804 Byte)The printed circuit board (PCB) of the Exactra 21 makes use of the TMS0803 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.

Don't miss a rare prototype of the Exactra 21 manufactured in early in 1974, probably only few weeks before the formal market introduction. Main difference to this late serial model is the display construction. 

If you are interested in the Exactra series you should view the remaining sibblings Exactra 19, Exactra 20, Exactra 22 and Exactra 23. Complete the line with the TI-2000 and Exactra 31.


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If you have additions to the above article please email:

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