zayre concept IIIzayre concept IIIModel: Concept III
Battery: 3 x AA
Adapter: AC9180
Year: 1976
Chip: TMS1016, SN27882 x 2
Manual: with permission

The Zayre CONCEPT Calculator Series culminated in March 1976 with the introduction of the Texas Instruments CONCEPT I, CONCEPT II, and CONCEPT III calculators based on the TI-1200, TI-1250, resp. SR-16 II but disappeared already in August 1979 with the clearance sales of the CONCEPT COMPACT calculators. Following the path of the Slide Rule (SR) calculators like the wonderful SR-16, the CONCEPT III was called Advanced Slide Rule. If you explore the calculator deeper, you'll immediately catch the similarities to the SR-16 II. The only differences are the coloring schema of the faceplate and the size of the letters. The slightly oversized keyboard printing was continued later with the TI-1255.Dismantling this Zayre CONCEPT III manufactured in February 1976 by Texas Instruments in Lubbock, Texas reveals no differences to the SR-16-II, the printed circuit board (PCBs) of the two calculators are 100% identical. Both the SR-16-II and this rare CONCEPT III calculator are based on a TMS1016 single-chip calculator circuit, a member of the famous TMS1000 Microcomputer family developed already in 1974.