Fairchild F8
Encyclopedia
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
created by Fairchild Semiconductor
Fairchild Semiconductor
Fairchild Semiconductor International, Inc. is an American semiconductor company based in San Jose, California. Founded in 1957, it was a pioneer in transistor and integrated circuit manufacturing...
. It was introduced in 1975 and was "the world´s leading microprocessor in terms of CPU sales" in 1977.
Features
The processor itself had no address bus — memory addresses were kept in each co-processor's own address counter and was manipulated through five control signals, reducing the number of pins and the associated cost. It also featured 64 bytes of scratchpad memory, accessed by the ISAR register in cells (register windows) of eight, which meant external RAM was not always needed for small applications. In addition, the 2-chip processor did not need support chips, unlike others which needed seven or more.The use of the ISAR register allowed a subroutine
Subroutine
In computer science, a subroutine is a portion of code within a larger program that performs a specific task and is relatively independent of the remaining code....
to be entered without saving registers, the ISAR would just be changed, speeding execution. Special purpose registers were usually stored in the second cell (regs 8-15), and only the first sixteen registers could be 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 ran at 1 MHz-2 MHz, yielding a .5uS cycle time.
History
The F8 was released in a single-chip implementation (the MostekMostek
Mostek was an integrated circuit manufacturer, founded in 1969 by ex-employees of Texas Instruments. Initially their products were manufactured in Worcester, Massachusetts, however by 1974 most of its manufacturing was done in the Carrollton, Texas facility on Crosby Road...
3870) in 1977.
The F8 was used in the Fairchild Channel F
Fairchild Channel F
The Fairchild Channel F is a game console released by Fairchild Semiconductor in August 1976 at the retail price of $169.95. It has the distinction of being the first programmable ROM cartridge-based video game console...
Video Entertainment System in 1976 and in the VideoBrain
VideoBrain Family Computer
The VideoBrain Family Computer is an 8-bit home computer manufactured by the VideoBrain Computer Company, starting in 1977. It is based on the Fairchild Semiconductor F8 CPU and is notable for being the first fully programmable cartridge-based home computer...
Computer system in 1977.
The F8 inspired other similar CPUs, such as the Intel 8048
Intel 8048
The MCS-48 microcontroller series, Intel's first microcontroller, was originally released in 1976. Its first members were 8048, 8035 and 8748....
.
Designers
One of the people responsible for developing it was Robert NoyceRobert Noyce
Robert Norton Noyce , nicknamed "the Mayor of Silicon Valley", co-founded Fairchild Semiconductor in 1957 and Intel in 1968...
who co-founded Fairchild but then left in 1968 to found Intel.