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Sharp QT-8D

Date of introduction:  October 1969 Display technology:  Fluorescent
New price:  $495 Display size:  8
Size:  9.8" x 5.4" x 2.8"    
Weight:  3 pounds 3 ounces Serial No:  151087
Batteries:   Date of manufacture:  year 1970
AC-Adapter:  220 V Origin of manufacture:  Japan
Precision:  8 Integrated circuits:  Rockwell Rockwell NRD2256, AC2261, DC2266, AU2271, CG1121
Memories:      
Program steps:   Courtesy of:  Joerg Woerner

If we trace the Timeline of calculating device starting from the early abacus and the Napier bones to the 20th century we get some important milestones:

1820 The Arithmometer
1874 The Ohdner calculator
1884 The Comptometer
1948 The Curta
1960 The first electronic calculators based on vacuum tubes
1964 The first transistor based calculators
1965 Texas Instruments started the Cal-Tech project leading
    to the first hand-held calculator prototype
1969 Sharp introduced with the QT-8D the first calculator using
    LSI-IC's (Large-Scale-Integration Chips) manufactured by
    US company Rockwell Electronics
1970 Sharp introduced its first battery operated desktop calculator QT-8B
1970 First battery operated, handheld calculators: 
    Busicom LE-120, Canon Pocketronic, Sanyo ICC-82D and Sharp EL-8.
1971 First portable, battery operated calculator using a 
    "Calculator-on-a-chip" appeared with the Bowmar 901B

Sharp Electronics Corporation introduced end of the year 1969 this important desktop calculator. A later version of the QT-8 (the QT-8B from 1970) included a rechargeable battery pack in order to make it portable. It is very similar to the first "really" portable, battery operated calculator, the EL-8.

Dismantling a Sharp QT-8D manufactured in 1970 reveals an impressive design similar to the later EL-8 using one printed circuit board (PCB) for the integrated display drivers and display module.

The display itself makes use of individual Itron fluorescent tubes with the odd trademark segmentation of early Sharp calculators.

An additional printed circuit board (PCB) hosts the brain of the calculator - the famous Rockwell chip set based on 4 larger Integrated Circuits (ICs) labeled NRD2256, AC2261, DC2266, AU2271 and a smaller clock driver labeled CG1121.

Read more about Sharp Corporation’s Calculator Innovations.

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If you have additions to the above article please email: joerg@datamath.org.

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