Well, I suppose RISC is about as close as you can get to that. Microcode, for reasons best known to someone familiar with CPU design, is not something you can just reprogram on the fly...
But RISC instructions are made to map to microcode (or *is* the microcode), allowing a programmer to fine tune the higher level instructions in whatever way they see fit. All the other fancy schmancy CPU stuff just keeps the instruction pipelines churning along at top efficiency. That's the long and short of it. Now, if all programmers were as concerned about optimizing code as George is, we could run Windows XP on a 286 system if you really wanted... optimized code can do wonders on even the slowest systems. :) Aaron ----- Original Message ----- From: "Steinar H. Gunderson" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, October 15, 2001 2:33 PM Subject: Mersenne: Re: AthlonXP > On Mon, Oct 15, 2001 at 07:35:36PM -0000, [EMAIL PROTECTED] wrote: > >What I would like to see in a CPU is a means where you could > >upload your own microcode, enabling design of specific instruction > >sets to handle particular problems very efficiently. > > What about (in an ideal world) just programming microcode directly, without > having to make an extra instruction set on top of that? Suddenly, you would > have both instant access to all the "ports" (or whatever the CPU makers call > their execution units these days), a lot of registers, etc.. In addition, the > problem with only a single decoder etc. on P4 would effectively go away > entirely. > > The only problem I could see would be a lot more code having to go over the > bus (and occupy more space in the instruction cache), especially as some > people have pointed out that the microcode might very well be some form of > VLIW :-) At least for us Linux users, having to recompile everything wouldn't > be _that_ big of a problem -- source for about everything you'd need would be > readily available (except that mprime would have to be ported, of course ;-) > )... _________________________________________________________________________ Unsubscribe & list info -- http://www.scruz.net/~luke/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
