- Fairchild F8
computing, the F8 was an 8-bit microprocessorcreated by Fairchild Semiconductor. It was introduced in 1975 and (according to at least one source) was the "the world´s leading microprocessor in terms of CPU sales" in 1977. [http://www.cpu-museum.com/F8_e.htm] One of the people responsible for developing it was Robert Noycewho co-founded Fairchild but then left in 1968 to found Intel. The processor itself had no address bus — program and data memory access were contained in separate units, which reduced the number of pins and the associated cost. It also featured 64 registers, accessed by the ISAR register in cells (register windows) of eight, which meant external RAM wasn't always needed for small applications. In addition, the 2-chip processor didn't need support chips, unlike others which needed seven or more.
The use of the ISAR register allowed a
subroutineto be entered without saving registers, speeding execution — the ISAR would just be changed. Special purpose registers were stored in the second cell (regs 9-15), and the first eight registers were accessed directly. The windowing concept was useful, but only the register pointed to by the ISAR could be accessed — to access other registers, the ISAR was incremented or decremented through the window.
The F8 was released in a single-chip implementation (the
Mostek3870) in 1977.
The F8 was used in the
Fairchild Channel FVideo Entertainment System in 1976.
The F8 was used in the VideoBrain Computer system in
The F8 inspired other similar CPUs, such as the
* [http://foldoc.org/index.cgi?query=fairchild+f8&action=Search Free On-Line Dictionary of Computing]
* [http://jbayko.sasktelwebsite.net/cpu2.html#Sec2Part2 The Great CPU List]
* [http://www.cpu-museum.com/F8_e.htm "8-bit Microprocessors - F8 (3850)"] , "cpu-museum.com".
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