12-bit computing: Difference between revisions

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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''' CPUCPUs isare 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 converter|analog to digital converters]] (ADCs) have a 12-bit resolution. Some [[PIC microcontroller]]s 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 [[Word (computer architecture)|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==

[[File:Living Computers - DEC PDP-8 (31826785627).jpg|thumb|[[Digital Equipment Corporation]] [[PDP-8]]e, a 12-bit minicomputer introduced in 1970]]

* [[Digital Equipment Corporation]]

** [[PDP-5]]