12-bit computing: Difference between revisions

Revision as of 22:03, 6 December 2021

Revision as of 22:20, 6 December 2021

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{{Short description|Computer architectures using a 12-bit word}}

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{{more footnotes|date=October 2009}}

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

Possibly the best-known '''12-bit''' CPU is the [[PDP-8]] and its relatives, such as the [[Intersil 6100]] microprocessor produced in various incarnationsforms 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.