page_title: History of general-purpose CPUs
section_title: 1970s: Microprocessor revolution
hierarchical_section_title: History of general-purpose CPUs / 1970s: Microprocessor revolution
caption_attribution_description: Français&#160;: Un processeur Intel C4004 avec traces grises (version sans traces grises). Esperanto: Procesoro Intel C4004 kun grizaj spuroj (versio sen grizaj spuroj). English: A processor Intel C4004 with grey traces (no gray trace version). Deutsch: Ein Prozessor Intel C4004 mit Leiterbahnen (ohne Leiterbahnen).
context_page_description: The history of general-purpose CPUs is a continuation of the earlier history of computing hardware.
context_section_description: The first commercial microprocessor, the binary coded decimal (BCD) based Intel 4004, was released by Busicom and Intel in 1971. In March 1972, Intel introduced a microprocessor with an 8-bit architecture, the 8008, an integrated pMOS logic re-implementation of the transistor–transistor logic (TTL) based Datapoint 2200 CPU.
  4004 designers Federico Faggin and Masatoshi Shima went on to design its successor, the Intel 8080, a slightly more mini computer-like microprocessor, largely based on customer feedback on the limited 8008. Much like the 8008, it was used for applications such as terminals, printers, cash registers and industrial robots. However, the more able 8080 also became the original target CPU for an early de facto standard personal computer operating system called CP/M and was used for such demanding control tasks as cruise missiles, and many other uses. Released in 1974, the 8080 became one of the first really widespread microprocessors.
  By the mid-1970s, the use of integrated circuits in computers was common. The decade was marked by market upheavals caused by the shrinking price of transistors.
  It became possible to put an entire CPU on one printed circuit board. The result was that minicomputers, usually with 16-bit words, and 4K to 64K of memory, became common.
  CISCs were believed to be the most powerful types of computers, because their microcode was small and could be stored in very high-speed memory. The CISC architecture also addressed the semantic gap as it was then perceived. This was a defined distance between the machine language, and the higher level programming languages used to program a machine. It was felt that compilers could do a better job with a richer instruction set.
  Custom CISCs were commonly constructed using bit slice computer logic such as the AMD 2900 chips, with custom microcode. A bit slice component is a piece of an arithmetic logic unit (ALU), register file or microsequencer. Most bit-slice integrated circuits were 4-bits wide.
  By the early 1970s, the PDP-11 was developed, arguably the most advanced small computer of its day. Almost immediately, wider-word CISCs were introduced, the 32-bit VAX and 36-bit PDP-10.
  IBM continued to make large, fast computers. However, the definition of large and fast now meant more than a megabyte of RAM, clock speeds near one megahertz, and tens of megabytes of disk drives.
  IBM's System 370 was a version of the 360 tweaked to run virtual computing environments. The virtual computer was developed to reduce the chances of an unrecoverable software failure.
  The Burroughs large systems (B5000, B6000, B7000) series reached its largest market share. It was a stack computer whose OS was programmed in a dialect of Algol.
  All these different developments competed for market share.
  The first single-chip 16-bit microprocessor was introduced in 1975. Panafacom, a conglomerate formed by Japanese companies Fujitsu, Fuji Electric, and Matsushita, introduced the MN1610, a commercial 16-bit microprocessor. According to Fujitsu, it was "the world's first 16-bit microcomputer on a single chip".
  The Intel 8080 was the basis for the 16-bit Intel 8086, which is a direct ancestor to today's ubiquitous x86 family (including Pentium and Core i7). Every instruction of the 8080 has a direct equivalent in the large x86 instruction set, although the opcode values are different in the latter.
caption: Intel 4004 microprocessor.
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