Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

SISC to RISC to ???

P

Paolo

macrumors regular
Original poster
Sep 21, 2001
182
0
The Moon
Hey I was tlaking to a friend who works in a processor resarch company, and there is talk in that there is something called ZISC chip technology (Zero Instruction SC (I forget what the SC stands for).
Is this even plausable!?
 
I think you mean

CISC = Complex Instruction Set Computer
RISC = Reduced Instruction Set Computer

A Zero Instruction Set Computer would be a lump of silicon! You may have got the wrong the end of the stick because ZISC as you call it sounds implausible.
 
Currently...

...the CISC chips are becoming more RISC like, and vice versa. To quote the guy at arstechnica, we're in the "post RISC" period now. Next, I think, is going to be VLIW (Very Large Instruction Word). Basically it makes the whole chip act like Altivec, although it's a lot more complicated than that. Currently Sun's MAJC chip, Transmeta's Crusoe, and Intel's Itanium use VLIW variants.
 
Okay this is something i've argued about before... I always learned that the last C stood for Completion, whereas many people think it's Computing, or computer as it says above. I know Completion was taken from a textbook on the subject, but i'm just curious... which one is technically right? anyone know for *sure*?

:)
pnw
 
Originally posted by paulwhannel
Okay this is something i've argued about before... I always learned that the last C stood for Completion, whereas many people think it's Computing, or computer as it says above. I know Completion was taken from a textbook on the subject, but i'm just curious... which one is technically right? anyone know for *sure*?

:)
pnw
Click to expand...
I've always known it as "chip." I looked it up at dictionary.com, and it says "computer."
 
Re: Currently...

mmmm image extraction....

so this is the kinda stuff they have in those retina scanning machiens eh?
 
To: daveGee

Thank You for the link. As an UI specialist, I found VERY interesting things from there. Superexciting.
 
Thanks for the link DaveGee. I'd never heard of this before.

Not sure it's really a zero instrucion set computer, the link has the ISA (Instruction Set Architecture) and PCI User's manual at the bottom so it does have a very small instruction set...

Still, very interesting.
 
I've known it as "chip" too, but "computer" seems widely used. Essentially, the RISC chip was origianlly designed because the instruction sets (the list of instructions that the CPU understands and can execute) were getting to long and complex. Chip designers realized that many of the commands were so complex and arcane that they were rarely used by programmers, and that the computer could execute essentially the same process with a string of simpler commands.

As an oversimplistic example, instead of having "add" and "multiply" commands, you could get away with only the "add" command; whenever you need to multiply, just add several times instead. The multiple-add process takes longer than the multiply process, but if you hardly ever multiply things anyway, then you don't lose much. However, since you have reduced your instruction set, your chip has less transistors, is smaller and more efficient, and runs faster in normal operations.

Keep in mind, however, that CISC and RISC refer as much to architecture as they do to instruction sets. Die size, pipeline length, cache layout etc. are now part of the CISC/RISC difference, and their instruction sets are getting less and less different from each other, as Catfish_Man noted.

Macs moved to RISC with System 7.5 in 1994, which necessitated a change of software, just like today with the switch to OS X, though not quite as radical. The new RISC system ran "PowerPC" software, and the old software was "68K." A backwards-compatible emulator was built-in so that old software could run, and software for a while was written in "fat" versions so both the old CISC and new RISC Macs could run it.

Windows machines are primarily CISC, but some have RISC chips, like AMD.

"ZISC" refers to neural network technology, a "learning computer" that analyzes data and builds recognition of patterns. They are trained, not programmed, and therefore do not have the instruction sets RISC or CISC machines do.

DaveGee's link is an excellent one; much more can be found with a simple Google search. You probably should not expect this to work its way into your computer at home for a while, and when it does, it will probably be auxilliary technology, not the CPU, until it is developed quite a bit further.

Tokyo
 
AMD...

Originally posted by Tokyo
I've known it as "chip" too, but "computer" seems widely used. Essentially, the RISC chip was origianlly designed because the instruction sets (the list of instructions that the CPU understands and can execute) were getting to long and complex. Chip designers realized that many of the commands were so complex and arcane that they were rarely used by programmers, and that the computer could execute essentially the same process with a string of simpler commands.

As an oversimplistic example, instead of having "add" and "multiply" commands, you could get away with only the "add" command; whenever you need to multiply, just add several times instead. The multiple-add process takes longer than the multiply process, but if you hardly ever multiply things anyway, then you don't lose much. However, since you have reduced your instruction set, your chip has less transistors, is smaller and more efficient, and runs faster in normal operations.

Keep in mind, however, that CISC and RISC refer as much to architecture as they do to instruction sets. Die size, pipeline length, cache layout etc. are now part of the CISC/RISC difference, and their instruction sets are getting less and less different from each other, as Catfish_Man noted.

Macs moved to RISC with System 7.5 in 1994, which necessitated a change of software, just like today with the switch to OS X, though not quite as radical. The new RISC system ran "PowerPC" software, and the old software was "68K." A backwards-compatible emulator was built-in so that old software could run, and software for a while was written in "fat" versions so both the old CISC and new RISC Macs could run it.

Windows machines are primarily CISC, but some have RISC chips, like AMD.

"ZISC" refers to neural network technology, a "learning computer" that analyzes data and builds recognition of patterns. They are trained, not programmed, and therefore do not have the instruction sets RISC or CISC machines do.

DaveGee's link is an excellent one; much more can be found with a simple Google search. You probably should not expect this to work its way into your computer at home for a while, and when it does, it will probably be auxilliary technology, not the CPU, until it is developed quite a bit further.

Tokyo
Click to expand...

...makes CISC chips (if anything can accurately be called CISC anymore). x86 is a CISC assembly language, it has to be decoded into micro-ops to be run.
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back