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You are here: MacNN Forums > Software - Troubleshooting and Discussion > macOS > OS X designed for CISC, not RISC

OS X designed for CISC, not RISC
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parsec
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Oct 21, 2002, 09:20 AM
 
As mentioned on slashdot,
an unsanity developer has posted in their weblog
that after inspecting os x's mach-o abi, it seems as though it makes use of legacy 68k code (i.e. CISC) instead of speeding things up by redesigning to make use of PowerPC chips.
Ah well. Things could always have been done better I guess, we would have just had to wait longer.
     
Nebrie
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Oct 21, 2002, 12:25 PM
 
already covered a few threads down. [url]http://forums.macnn.com/showthread.php?s=&threadid=128416[url]
     
OreoCookie
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Oct 21, 2002, 04:42 PM
 
DOS was designed for an 8 bit chip. But it also ran on my 486 (32 bit)). So what.
I don't suffer from insanity, I enjoy every minute of it.
     
:XI:
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Oct 21, 2002, 04:55 PM
 
and wasn't os 9 and under designed originally for the same 68k chip?
     
The Godfather
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Oct 21, 2002, 09:08 PM
 
Is a CISC PowerPC CPU even possible? Call the AMD company!
     
Sarc
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Oct 22, 2002, 12:54 AM
 
was thinking the same thing, is it possible to have CISC PowerPC ?
Sounds more like they are keeping "our options open" so they can adopt other architecture.


Sarc
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el chupacabra
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Oct 22, 2002, 01:57 AM
 
CISC vs RISC is explained at www.arstechnica.com for those of you who don't understand it quite well.

PowerPC is a trademark so if whoever owns it decides to make RISC chips and call them PPC then it is possible but if you mean is it possible to have a RISC/CISC (ie half and half) processor then the answere is yes.
the largest problem for Americans today is they eat too much food and dont have enough work to do to keep their heart healthy
     
stew
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Oct 22, 2002, 02:10 AM
 
Originally posted by OreoCookie:
DOS was designed for an 8 bit chip. But it also ran on my 486 (32 bit)). So what.
The 486 is fully compatible to the 8088. PowerPCs however lack the 68k PC register, which the Mach-O format supposedly is making heavy use of.


Stink different.
     
sadie
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Oct 22, 2002, 04:58 AM
 
It's not that it uses code from 68k. Rather, it uses the PowerPC as if it were a CISC - particularly in the use of 68k specific registers, and so on. These registers basically get emulated on a PowerPC. All in all, it's not a very efficient design.

The article says that it results in something like a 10% performance hit on most code. With Moore's Law creaking at the edges, and Apple trailing behind in all things speed-related, this is a significant difference - if it's true.
All words are lies. Including these ones.
     
eno
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Oct 22, 2002, 06:59 AM
 
Evident from most of the posts on this thread that nobody actually bothered to read the piece by the Unsanity guy, or, if they did, they're too stupid or unschooled to comprehend it. (Last poster excluded from this.)

Anyway, as has already been said, there's already a thread on this: use it.
     
El Pre$idente
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Oct 22, 2002, 07:32 AM
 
I always said Apple made sure the OS and the graphics display model was made slow to make people upgrade their Macs. And now Unsanity developer's agree:

'Either way, there is no way to change the ABI now, as it would break all of the existing applications - which is obviously not what Apple (or us) would want.
And after all, who cares about a 10% speed loss? You can always get a faster Mac, right?'
     
   
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