Intel 8080 microprocessor is a successor to the
Intel 8008 CPU. The 8080 was designed by
Federico Faggin and Masatoshi Shima. Stan Mazor contributed to chip
design. The work on 8080 microprocessor was started at the end of
1972, and the CPU was released in April of 1974. Original version of
the 8080 had a flow - it could only drive low-power TTL devices. After
the flow was discovered Intel released updated version of the CPU - 8080A,
which could drive standard TTL devices.
The Intel 8080/8080A was not object-code compatible with the 8008, but
it was source-code compatible with it. The 8080 CPU had the same
interrupt processing logic as the 8008, which made porting of old applications
easier. Maximum memory size on the Intel 8080 was increased from 16
KB to 64 KB. The number of I/O ports was increased to 256. In addition
to all 8008 instructions and addressing modes the 8080 processor
included many new instructions and direct addressing mode. The 8080
also included new Stack Pointer (SP) register. The SP was used to
specify position of external stack in CPU memory, and the stack could
grow as large as the size of memory. Thus, the CPU was no longer
limited to 7-level internal stack, like the 8008 did.
The Intel 8080 microprocessor was very popular and was second-sourced
by many manufacturers. Clones of the 8080 processor were made in USSR,
Poland, CSSR, Hungary and Romania.
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