12-bit computing

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title: "12-bit computing" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["computer-data"] description: "Computer architecture bit width" topic_path: "general/computer-data" source: "https://en.wikipedia.org/wiki/12-bit_computing" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Computer architecture bit width ::

Before the widespread adoption of ASCII in the late 1960s, six-bit character codes were common and a 12-bit word, which could hold two characters, was a convenient size. This also made it useful for storing a single decimal digit along with a sign. Possibly the best-known 12-bit CPUs are the PDP-8 and its descendants (such as the Intersil 6100 microprocessor), which were produced in various forms from August 1963 to mid-1990. Many analog to digital converters (ADCs) have a 12-bit resolution. Some PIC microcontrollers use a 12-bit instruction word but handle only 8-bit data.

12 binary digits, or 3 nibbles (a 'tribble'), have 4096 (10000 octal, 1000 hexadecimal) distinct combinations. Hence, a microprocessor with 12-bit memory addresses can directly access 4096 words (4 kW) of word-addressable memory. IBM System/360 instruction formats use a 12-bit displacement field which, added to the contents of a base register, can address 4096 bytes of memory in a region that begins at the address in the base register.

List of 12-bit computer systems

::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/b7/Living_Computers_-DEC_PDP-8(31826785627).jpg" caption="[[Digital Equipment Corporation]] [[PDP-8]]e, a 12-bit minicomputer introduced in 1970"] ::

• Digital Equipment Corporation
  • PDP-5
  • PDP-8
    • DECmate, a personal computer based on the Intersil 6100
  • PDP-12
  • PDP-14
• Ford EEC I automotive engine control unit
  • Toshiba TLCS-12 microprocessor
• Intersil IM6100 microprocessor (PDP-8-compatible)
• Control Data Corporation
  • CDC 160 series computers
  • CDC 6600 - Peripheral Processor (PP)
• National Cash Register NCR 315
• Scientific Data Systems SDS 92
• Nuclear Data, Inc. ND812
• PC12 minicomputer
• Ferranti Argus
• LINC, later commercialized by DEC as the LINC-8

References

References

1. "1973: 12-bit engine-control microprocessor (Toshiba)".

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::