Manuel Bouyer wrote:
On Wed, Aug 05, 2009 at 12:47:01PM -0400, Kurt J. Lidl wrote:[...] The coldfire is like a m68k in terms of assembly instructions, and general purpose registers, but most of the other really low-level stuff (floating point, MMU) is different. Does the instruction set similarity with the m68k just cloud the issue that this is really a different family of processors?Is the instruction set different enough so that 68020 userland binaries won't run on a coldfire ? If so, I'd say it's a different processor family. Differences in MMU can be dealt with inside the same family without problems.
Without heroic programming effort, no, they won't run. If you setup the coldfire with enough illegal instruction handlers and illegal memory access handlers, you can make *most* code that doesn't do floating point sorta work. In fact, such a beast exists: http://www.microapl.co.uk/Porting/ColdFire/cf68klib.html But, it's really implementing a huge amount of the m68k architecture as exception handler fixups. Sorta interesting from an academic view in that it *can* be done, but not terribly interesting to actually implement. Well, at least not interesting to me. I'd guess that points towards a new processor family. -Kurt