12-bit computing: Difference between revisions

Revision as of 12:14, 28 January 2023

Revision as of 16:41, 19 November 2023

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{{N-bit|12|(1.5 octets)}}

Before the widespread adoption of [[ASCII]] in the late 1960s, [[six-bit character code]]s 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''' CPU is the [[PDP-8]] and its relatives, such as the [[Intersil 6100]] microprocessor produced in various forms from August 1963 to mid-1990. Many [[Analog-to-digital converter|analog to digital converters]] (ADCs) have a 12-bit resolution. Some [[PIC microcontroller]]s use a 12-bit word size.

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 [[Word (computer architecture)|words]] (4 kW) of [[word-addressable]] memory. At a time when [[six-bit character code]]s were common a 12-bit word, which could hold two characters, was a convenient size. 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.

==List of 12-bit computer systems==