Additional Pictures 


This Radio Shack EC-4000 was manufactured in July 1979 by
Texas Instruments in Abilene, TX (Date code ATA 2979 wk 29 yr 1979).

The printed circuit board (PCB) of the EC-4000 looks very familiar to us.
It is 100% identical with the Texas Instruments TI-57 Programmable.

If you have additions to the above article please email:

Joerg Woerner, November 11, 2009. No reprints without written permission.