Sharp QT-8D

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Sharp QT-8D
The inside of the computer with the four LSI ICs. On the right the circuit board with the power supply electronics

The Sharp QT-8D “Micro Compet” is a compact desktop computer and is considered to be the first computer whose logic modules were implemented using LSI technology. Earlier electronic calculating machines consisted of numerous discrete transistors and diodes as well as weakly integrated ICs , but in the QT-8D introduced at the end of 1969, only four ICs developed by Rockwell , each of which corresponds to around 900 transistors, took on all essential tasks.

The display of the QT-8D consists of eight Digitron tubes in which a number is composed of eight unusually shaped segments. The arithmetic operations that can be carried out are limited to the four basic arithmetic operations . The keyboard has 15 keys, with the multiplication and division sharing one key - the decisive factor here is whether the arithmetic operation is completed with +=or −=.

Compared to the earlier calculating machines, the LSI technology not only allowed a strong reduction in dimensions, but also in power consumption. A logical further development of the QT-8D was therefore the QT-8B, released in mid-1970, which instead of the integrated power supply contained a battery pack with six NiCd cells and thus became the first network-independent electronic calculator.

Based on the four ICs of the QT-8D, the EL-8 , introduced in 1971, was also created , which is considered the world's first pocket calculator.

Web links

Individual evidence

  1. Vintage Calculators Web Museum - Sharp QT-8B