Motorola 68851

The Motorola 68851 is an external Memory Management Unit (MMU) which is designed to provide paged memory support for the 68020 using that processor's coprocessor interface. In theory it can be used with other processors such as the 68010 by simulating the coprocessor interface in software.

Later 68K family processors such as the 68030, 68040, and 68060 have an internal MMU, and will not operate with the 68851, except possibly by simulation of the coprocessor interface.

The 68851 was available as an option for the Apple Macintosh II, and was necessary to run Apple's A/UX operating system.

Very few cards for the Amiga make use of the 68851 primarily because it can only be used with a small range of processors and most Amigas and accelerator cards use a processor which either has its own MMU or cannot support an MMU. One of the few cards which does use this is the Commodore A2620.

This computer hardware article is a stub. You can help Wikipedia by expanding it.v · Categories: Virtual memory Computer hardware stubs Wikimedia Foundation. 2010. Игры ⚽ Поможем написать курсовую KJZS Aarne Juutilainen Look at other dictionaries: Motorola 68000er-Familie — Motorola MC68000 im 64 poligen DIP Motorola 68 …   Deutsch Wikipedia Motorola 680x0 — Die Motorola 68000er Familie, auch als 680x0 oder m68k bzw. 68k bezeichnet, ist eine Serie von CISC Mikroprozessoren der Firma Motorola. Alle Prozessoren dieser Serie haben einen einfachen aber mächtigen Befehlssatz mit vielen Adressierungsarten… …   Deutsch Wikipedia Motorola 68330 — Die Motorola 68000er Familie, auch als 680x0 oder m68k bzw. 68k bezeichnet, ist eine Serie von CISC Mikroprozessoren der Firma Motorola. Alle Prozessoren dieser Serie haben einen einfachen aber mächtigen Befehlssatz mit vielen Adressierungsarten… …   Deutsch Wikipedia Motorola 68020 — XC68020, un prototipo del 68020. Motorola 68020 …   Wikipedia Español Motorola 68EC030 — Motorola 68030 Motorola 68030 à 50 MHz Le Motorola 68030 et sa version économique 68EC030 est un microprocesseur CISC 32 bits de la famille m68k de Motorola. Le 68030 est le successeur du Motorola 68020 et fut suivi par le Motorola 68040. Ce… …   Wikipédia en Français Motorola 68030 — microprocessor The Motorola 68030 is a 32 bit microprocessor in Motorola s 68000 family. It was released in 1987. The 68030 was the successor to the Motorola 68020, and was followed by the Motorola 68040. In keeping with general Motorola naming,… …   Wikipedia Motorola 68030 — à 50 MHz Le Motorola 68030 et sa version économique 68EC030 est un microprocesseur CISC 32 bits de la famille m68k de Motorola, produit en 1987. Le 68030 est le successeur du Motorola 68020 et fut suivi par le Motorola 68040. Ce processeur est… …   Wikipédia en Français Motorola 68000 family — Motorola 68000 Designer Motorola Bits 16/32 bit Introduced 1979 Design CISC Endianness Big Registers General p …   Wikipedia Motorola 68EC020 — Motorola 68020 Un XC68020, prototype du MC68020 …   Wikipédia en Français Motorola 6800 — Motorola MC6800 Microprocessor. The 6800 was an 8 bit microprocessor designed and first manufactured by Motorola in 1974. The MC6800 microprocessor was part of the M6800 Microcomputer System that also included serial and parallel interface ICs,… …   Wikipedia 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”