View source for Motorola M68000 Family

The '''Motorola 68000 family''' (also 680x0, 68K, etc) is a series of [[VLSI]] [[microprocessor]]s, successor to Motorola's prior [[Motorola M6800]].

Although the first in the series (the [[MC68000]]) was described by Motorola as a "16-bit microprocessor", the family is generally considered to be a 32-bit. In a number of important aspects of an [[architecture]]:

* Word ([[address space]]) size
* Register length
* Many operations (arithmetical, logical, etc)

all shared by all members of the family (which are generally compatible at the [[object code]] level) it is a 32-bit machine. (A large share of the instructions are only 16 bits long, however.)

The earliest member of the family (the [[MC68000]] did not support [[virtual memory]] or [[virtualization]], but all the later members did. The 68K family is a [[Complex Instruction Set Computer|CISC]] architecture.

The architecture shows clear influences from the [[PDP-11 architecture]], including auto-increment and -decrement modes for stack support and array operations, memory-mapped I/O, etc. In other ways it has similar approaches to the PDP-11, including large numbers of general-purpose registers, a very orthogonal instruction set, etc, although it is harder to say definitively what the source was.

During their lifetime (in the 1980s and early 1990s), they were popular, initially in small [[time-sharing]] systems, and then [[workstation]]s (e.g. the [[Sun workstation]]) and finally in [[personal computer]]s (notably the [[Apple Macintosh]].

In the latter role, their primary competition was the [[Intel x86]] microprocessor line. They are no longer used in personal computers, but derivatives are still in wide use in embedded systems.

Motorola ceased development of the 68000 family in 1994, when they moved to the [[Motorola 88000 family]] of [[Reduced Instruction Set Computer|RISC]] processsors, and soon thereafter the [[PowerPC]] family, in collaboration with [[International Business Machines|IBM]] and [[Apple Computer]].

* First generation - internally 16/32-bit
** [[MC68000]]/MC68008
** [[MC68010]]/[[MC68012]]
* Second generation - fully 32-bit
** [[MC68020]]
** [[MC68030]]
* Third generation - integral memory management
** [[MC68040]]
* Fourth generation - superscalar
** [[MC68060]]

[[Category: Microprocessors]]