Author: Tom Kerrigan
Date: 18:03:30 06/30/03
Go up one level in this thread
On June 29, 2003 at 23:50:11, Robert Hyatt wrote: >On June 29, 2003 at 06:35:02, Tony Werten wrote: > >>On June 28, 2003 at 14:23:50, Robert Hyatt wrote: >> >>>On June 28, 2003 at 12:12:15, Jay Urbanski wrote: >>> >>>>On June 28, 2003 at 10:33:45, Robert Hyatt wrote: >>>> >>>>>Those are not true 64 bit processors. Supposedly 32 bit stuff runs just >>>>>fine on them, but they have 64 bit extensions. >>>> >>>>How is Opteron not a true 64-bit processor? >>> >>> >>>Because it executes 32 bit instructions _also_. >> >>P4 and AMD also execute 16-bit instructions, so they are 16 bit processors ? > >Not pure 16 bit no. Not pure 32 either. > >Check out "Cray" for a better example of a pure architecture. > >All math is 64 bits. All address arithmetic is 32 bits. Different >instructions, functional units, and registers for each. No kludges about >gating 32 bits with 32 high-end zeroes and that kind of stuff. > >But in the case of opteron, at least at first look, it appears to be a 32 >bit machine with 64 bit instructions layered on top. Are you kidding me? The "bitiness" is the width of a chip's datapath, right? The Athlon and Pentium quite obviously have a 32 bit datapath so they are 32-bit chips. The Opteron has a 64 bit datapath so it's a 64-bit chip. I don't know what you mean by "64 bit instructions layered on top." -Tom
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