Royal DT 80

Date of introduction:  1985 Display technology:  LCD
New price:   Display size:  8
Size:  4.7" x 4.1" x 1.0"
 120 x 106 x 25 mm3
Weight:  3.0 ounces, 86 grams Serial No:  
Batteries:  n.a.  Date of manufacture:  year 1986
AC-Adapter:   Origin of manufacture:  Taiwan
Precision:  8  Integrated circuits:  Sharp
Memories:  1    
Program steps:   Courtesy of:  Joerg Woerner

Does Royal DT 80 calculator sold in 1986 look familiar to you?

Dismantling the featured DT 80 manufactured in 1986 by Compal Electronics, an OEM (Original Equipment Manufacturer) in Taiwan, reveals a clean design centered around an unknown Sharp single-chip calculator circuit soldered on a double-sided printed circuit board (PCB) and powered by solar cells.

Inspecting the PCB of this DT 80 brought our attention to a small mark reading SD9-14, most likely a reference to Type Small Desktop 9 and Revision 1.4 of the design (schematics and layout). We spotted this PCB-Mark already with the near identical offspring TI-1795 and Radio Shack EC-2006A with revisions SD9-13, SD9-14, and SD-9-15. We started compiling a list of the PCB-Marks on calculators manufactured by OEMs for Texas Instruments.

IIf you have additions to the above article please email:

Joerg Woerner, April 13, 2020. No reprints without written permission.