Fairchild F8

An 8-bit {microprocessor}. 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 {register}s, accessed by the ISAR register in cells ({register window}s) 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 F8 inspired other similar {CPU}s, such as the {Intel 8048}. The use of the ISAR register allowed a subroutine to be entered without saving a bunch of 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. (1994-11-16)