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 AC2261, AU2271, DC2266, NRD2256
Program steps:   Courtesy of:  Joerg Woerner

If we trace the Time-line 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.

Do get an impression about the valuable internal construction just take your time and watch the next five pictures carefully.

This photo gives you an idea of the sleek design of the calculator. QT-8D_1.jpg (63016 Byte)
The display uses its own printed circuit board with the driving electronics. 

QT-8D_pcb3.jpg (27255 Byte)

The display is made from single tubes with odd segmentation.  QT-8D_disp.jpg (28453 Byte)
The printed circuit board of the calculator brain shows the famous chip-set developed by US company Rockwell. The same chips are used in the smaller EL-8. QT-8D_pcb1.jpg (91978 Byte)
An impressive view of one of the Rockwell calculator chips. Only Rockwell used the staggered layout of the pins. The datecode 7025 on top of the gold hood gives a manufacturing date mid of 1970. QT-8D_pcb2.jpg (22609 Byte)


Read more about Sharp Corporation’s Calculator Innovations.

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