I guess it depends on your "commercial PC"
definition:
Intel 8080 microprocessor is a successor to the
Intel 8008 CPU. To ease transition to the 8080
Intel made the new microprocessor source code
compatible with the 8008. Interrupt processing
logic didn't change from the 8008, which also
helped to port old software to the 8080
processor. The 8080 processor included many
enhancements:
* Maximum memory size was expanded to 64 KB.
* Stack size was no longer limited to 7 levels.
* The number of I/O ports was increased to 256.
* The processor included many new
instructions and direct addressing mode.
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.
Computers: Altair 8800, IMSAI 8080, CompuColor
II, Byte Computers Byt-8
Intel 8080
The Intel 8080 was an early microprocessor
designed and manufactured by Intel. The 8-bit
CPU was released in April 1974 running at 2 MHz,
and is generally considered to be the first
truly usable microprocessor CPU design.
Description
The Intel 8080 was the successor to the Intel
8008 (with which it was assembly language
source-compatible because it used the same
instruction set developed by Computer Terminal
Corporation). The 8080's large 40 pin DIP
packaging permitted it to provide a 16-bit
address bus and an 8-bit data bus, allowing easy
access to 64 kilobytes of memory. It had seven
8-bit registers (six of which could be combined
into three 16-bit registers), a 16-bit stack
pointer to memory (replacing the 8008's internal
stack), and a 16-bit program counter.
The 8080 had 256 I/O ports (allowing I/O devices
to be connected without the need to allocate
memory space – as is required for memory mapped
devices – but at the expense of having
programmers deal with separate I/O instructions).
The first single-board microcomputer was built
on the basis of the 8080.
Impact
The 8080 was used in many early computers, such
as the MITS Altair 8800 and IMSAI 8080, forming
the basis for machines running the CP/M
operating system (the later, fully compatible
and more capable, Zilog Z80 processor would
capitalize on this, with Z80 & CP/M becoming the
dominant CPU & OS combination of the period much
like x86 & MS-DOS for the PC a decade later).
Shortly after the launch of the 8080, the
Motorola 6800 competing design was introduced,
and after that, the MOS Technology 6502 clone of
the 6800.
At Intel, the 8080 was followed by the
compatible and electrically more elegant 8085,
and later by the assembly language compatible
16-bit 8086 and then the 8/16-bit 8088, which
was selected by IBM for its new PC to be
launched in 1981. The 8080, via its ISA, thus
made a lasting impact on computer history.
