page_title: Intel 4004
section_title: Name and variants
hierarchical_section_title: Intel 4004 / History and production / Name and variants
caption_attribution_description: The UniCom 141P printing calculator sold for $695 when introduced in 1972. It was built by Busicom Corp of Japan (formerly Nippon Calculating Machine). The calculator was initially sold as the Busicom 141-PF and then was sold by UniCom and National Cash Register. The integrated circuits used in the calculator were a result of a joint development effort by Busicom and Intel. Intel offered the chip set as the MCS-4 microcomputer system in November 1971. It included the Intel 4004 4-bit CPU, one of the earliest microprocessors. This description is from an advertisement in the July 1972 issue of The Office - Magazine of Management, Equipment, Automation. "Performs chain calculations with or without printing of the intermediate answers. Has two accumulators plus a powerful working register. Lets you flip-flop amounts between registers when multiplying or dividing. Has two complete decimal systems -full floating or floating in/fixed out. Works percentages without decimal indexing. Prints three lines a second, identifies every item, and shows negative answers in red. Performs automatic duplex functions. Weighs just 11 pounds and takes up only a little more desk space than a letterhead." UniCom, 10670 North Tantau Avenue, Cupertino, California 95014 The calculator in this picture was purchased at a thrift store in 2004 for $5 by Sellam Ismail, creator of the Vintage Computer Festival. This photo was taken at VCF 10 held at the Computer History Museum in Mountain View, CA, November 3-4, 2007 by Michael Holley using a Canon PowerShot A630.
context_page_description: The Intel 4004 is a 4-bit central processing unit released by Intel Corporation in 1971. It was the first commercially produced microprocessor, and the first in a long line of Intel CPUs.
  The chip design, implemented with the MOS silicon gate technology, started in April 1970, and was created by Federico Faggin who led the project from beginning to completion in 1971. Marcian Hoff formulated and led the architectural proposal in 1969, and Masatoshi Shima contributed to the architecture and later to the logic design. The first delivery of a fully operational 4004 occurred in March 1971 to Busicom Corp. of Japan for its 141-PF printing calculator engineering prototype. This calculator for which the 4004 was originally designed and built as a custom chip
  was first commercially available in July 1971.
  The 4004 was the first random logic circuit integrated in one chip using the MOS silicon gate technology. It was the most advanced integrated circuit design undertaken up until then.
context_section_description: When Faggin designed the MCS-4 family, he also christened the chips with distinct names: 4001, 4002, 4003, and 4004, breaking away from the numbering scheme used by Intel at that time which would have required the names 1302, 1105, 1507, and 1202 respectively. Had he followed Intel's number sequence, the idea that the chips were part of a family of components intended to work seamlessly together would have been lost. Intel's early numbering scheme for integrated circuits used a four-digit number for each component. The first digit indicated the process technology used, the second digit indicated the generic function, and the last two digits of the number were used to indicate the sequential number in the development of the component. The 8008 microprocessor was originally called 1201, per Intel's naming conventions. Before its market introduction, the 1201 was renamed 8008, following the new naming convention started with the 4001/4002/4003/4004.
  Tadashi Sasaki attributes the basic invention to break the calculator into four parts with ROM (4001), RAM (4002), shift registers (4003) and CPU (4004) to an unnamed woman from the Nara Women's College present at a brainstorming meeting that was held in Japan prior to his first meeting with Robert Noyce from Intel, leading up to the Busicom deal.
  The 4004 is part of the MCS-4 family of LSI chips that can be used to build digital computers with varying amounts of memory. The other members of the MCS-4 family are memories and input/output circuits, which are necessary to implement a complete computer. The 4001 is a ROM (read-only memory) with four lines of output; the 4002 is a RAM (random access memory) with four lines of input/output. The 4003 is a static shift register to be used for expanding the I/O lines; e.g., for keyboard scanning or controlling a printer.
  The 4004 includes functions for direct low-level control of memory chip selection and I/O, which are not normally handled by the microprocessor; however, its functionality is limited in that it cannot execute code from RAM and is limited to whatever instructions are provided in ROM (or an independently loaded RAM working as ROM—in either case, the processor is itself unable to write or transfer data into an executable memory space). The RAM and ROM parts were also unusual in their integration of output (and, in the ROMs, input) ports that significantly reduced the minimum part count in an MCS-4 system, but required inclusion of a certain amount of processor-like logic on the chips themselves to accept, decode and execute relatively high-level data transfer instructions.
  The standard arrangement for a 4004 system is anything up to 16 × 4001 ROM chips (in a single bank) and 16 × 4002 RAM chips (in four banks of four), which together provide the 4KB program storage, 1024 + 256 nibbles of data/status storage, plus 64 output and 64 input/output external data/control lines (which can themselves be used to operate, e.g. a 4003). Intel's MCS-4 documentation, however, claims that up to 48 ROM and RAM chips (providing up to 192 external control lines) "in any combination" can be connected to the 4004 "with simple gating hardware", but declines to give any further detail or examples of how this would actually be achieved.
caption: The Unicom 141P is an OEM version of the Busicom 141-PF
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