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| Newer page: | version 8 | Last edited on Thursday, July 7, 2005 4:36:25 am | by AristotlePagaltzis | Revert |
| Older page: | version 7 | Last edited on Thursday, July 7, 2005 4:35:34 am | by AristotlePagaltzis | Revert |
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A family of [CPU]s made by [Motorola], sometimes also referred to as "68k".
-It
has 16 32-bit registers, split into 8 data and 8 address registers. The instruction set is quite orthogonal and instructions are always multiples of 16 bits in length. Accesses to anything larger than a byte have to be 16-bit aligned. Overall, the architecture has a strong [RISC] feel to it, though it is not. The architecture
has always been fully 32-bit, as opposed to the [x86] design, which started out as a 16-bit design that was painfully evolved to 32-bit.
+The design
has 16 32-bit registers, split into 8 data and 8 address registers. The instruction set is quite orthogonal and instructions are always multiples of 16 bits in length. Accesses to anything larger than a byte have to be 16-bit aligned. Overall, the architecture has a strong [RISC] feel to it, though it is not. It
has always been fully 32-bit, as opposed to the [x86] design, which started out as a 16-bit design that was painfully evolved to 32-bit.
The 68000, the first in the series, was introduced in September 1979, and only had a 24-bit address bus. The 68010, introduced in 1982, allowed the use of VirtualMemory, but offered too little additional further advantages to justify its price in the eyes of most customers. The 68020, debuting in 1984, was fully 32-bit, and software could take immediately advantage of this because the architecture had always been designed for the fact. The 68k family enjoyed wide deployment, and is nowadays still used in embedded devices. Some architectures built around this [CPU] family include:
* The AppleLisa and the AppleMacintosh.
