Advanced Micro Devices Inc (AMD)

[sgolds]

HailMary, I agree that there will be no new architectures for a long time. I differ from your list of survivors because I would add Power and put a big question mark near IPF:

x86 - long live the king!
IPF - ??? - can it survive beyond the decade?
Power - IBM seems to be positioning it nicely.
SPARC - Nahhh.

Maybe over time x86 will be able to drop most of the legacy ugliness and become more useful.

More useful? I guess you must mean 'continued useful'. Any case, have a look at the 64-bit design of AMD64. It is designed to cut off the legacy stuff over time. There are two major modes, and each one has two sub-modes:

Long Mode supports 64-bit Mode and Compatibility Mode. 64-Bit Mode uses new 64-bit instructions only. Compatibility Mode supports 32-bit and 16-bit Protected Modes applications under a 64-bit OS (underlying control structures are 64-bit, so it is kind of a Protected Mode emulation).

Legacy Mode supports the stuff that (IMHO) is partitioned to be jettisoned later: Protected Mode, Virtual-8086 Mode and Real Mode.

I expect that it won't be long before we see a version of Opteron that leaves off Legacy Mode. After all, who needs it on a server? If you run a 64-bit OS then each application is being run either directly in Long Mode, or in Compatibility Mode to emulate the current environment. Under that 64-bit OS, Legacy Mode isn't even available!

The upgrade path is very nicely done. Anyone who thinks of this scheme as an extension of x86-32 is fooling himself: It is a way of replacing x86-32 with a whole new scheme in an upgradable manner. New register structure, new opcodes, everything changes.

Edit: I've been wondering about all the new cores that AMD is releasing on their roadmap. Maybe some of the high-end cores will not have Legacy Mode at all.