Intel 8080
The Intel 8080 was an early CPU designed and manufactured by Intel. It was released in April 1974 running at 2MHz, and is generally considered to be the first truely usable microprocessor design. It was used in many early computers, and formed the basis for machines running CP/M.
The Intel 8080 successor to the Intel 8008. The 8080 (permitted by its large 40 pin DIP packaging) had a 16-bit address bus and an 8-bit data bus. It had seven 8-bit registers (six which could also be combined as three 16-bit registers), a 16-bit stack pointer to memory which replaced the 8008's internal stack and a 16-bit program counter. It also had 256 I/O ports (so I/O devices could be connected without needing to allocate any addressing space as is required for memory mapped devices).
Shortly after the 8080, the Motorola 6800 was introduced.
See also:
This article (or an earlier version of it) contains material from FOLDOC, used with permission.