h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Hmm... what's so great about a 64 bit chip?

I'm probably being naive here, but it seems t'me that 32 bits is plenty for virtually all purposes... and using 64 across the board is just wasteful?...

Itanium is Intel's 64-bit server platform. It's available now, but expensive and not so widely adopted at the moment... I believe there's a version of Windows XP which runs on it and is even more hideously expensive than normal Windows. The problem with Itanium of course is that it's got a totally new instruction set - while this is good in terms of ultimate performance capability, it's bad because old software won't run on it. At all.

AMD, on the other hand, just extended the x86 architecture, added two new instructions to handle 64-bit stuff (don't ask me how they got away with just two) and are thus 100% backward compatible, which should mean that their Hammer chips (some will be called Athlons, confusingly, while others will be called Opterons) get very good desktop penetration quite quickly.

As for the advantages of 64 bit, speed is potentially greater - you can, for instance, load twice as much data into a CPU register with one instruction than you can with a 32 bit processor. This makes a huge difference, as data loads and saves to main memory take absolutely ages compared with a processing instruction (like an add). Various other things end up being faster as well, and of course it's an excuse to beef up the system bus as well, which could _always_ do with being faster, ever since they came up with the idea of running the processor clock faster than the system clock (mine's running 13 times faster than the bus speed... memory write lag must be enormous).

Ah, good point... hmm... although that does rely on storing data in 64-bit words. Bit messy for some things...

And just when graphics had escaped from the headaches of having more than one pixel per word...

Then again, I guess bit shifts and such are pretty darn fast.

the reason for shifting to 64 bit is the same as for the move from 8 bit to 16 bit, and the to 32 bit.

The problem I have with it is that although ALL current 32 chips use a risc architechture internally, you are still getting the stupidities of using an a cisc architechture as the external interface.

Acorn proved in the eighties (confirming what IBM had shown in the seventies) that risc blows the doors of all other (non-speciality) architectures.

Also, it is much easier to parallelise the internal architecture of a risc chip, so that it runs asynchronously instead of having the usual clocking problems.

I'm not sure, but I think Itanium might have a RISC instruction set or something very like it... if not, Intel are silly because there's not really any reason to design Itanium any other way if it's RISC cored, because they already threw backward compatibility right out of the window.

Risc chips, so I've heared are quite fast, but 64bits is nothing, I'm holding down for a 20 channel 32 line light bus, with 40Thz Cystal CPU. it's only a matter of years...

imagine it though, it would be like having 20 prosesors each with a 32bit bus, and fluent translation between each one, whith none of this heat proplems, (I can but dream again)

-- DoctorMO --