| From: | Matt Sealey |
| Date: | 23 Apr 2001 at 18:29:36 |
| Subject: | Re: Common misconception (was Re: Voyager Image Decoders) |
Hello Alan
On 23-Apr-01, you wrote:
> hi,
>
>> The 68060 FPU is very good, and that is the 68k emulator's stumbling block
>> for sure (simply because the FPU on a 603e isn't as fast, and scarily enough
>> the 604e one is slower :)
>
> ?? the 604 FPU is slow than the 603e's , but both of them easily beat that
> on the 060 :-)
They're different beasts: CISC and RISC. To perform CISC style instructions
on a RISC chip takes many times the number of instructions. Even the simplest
would take, say, four decent instructions to perform, each taking, lets say,
one processor cycle each.
Now, when your PPC processor only clocks in at 4x the speed of your 68k
processor, and there are some HIDEOUSLY complex FPU things that a 68k
will do that a PPC doesn't (even the 68060, which had it's FPU rationalised)
you can see where the performance hit is.
At 50MHz, the 68060 FPU would outperform the 603e FPU :P
>> Do some integer tests, run around in Workbench for a while, and it'll feel
>> pretty much like it would on a 68060. The context switches between
>
> it doesnt. trust me, i've an 060 (as you know) and workbench isnt 'pretty
> much like' . its not as bad as it felt on 50Mhz 030, but it is around the
> 040 mark. of course, when starting to use bits that are now on the PPC it
> is much better..did I say native PPC disk access?? :-)
scsi rul0rz ;P
>> How would Mac people know? They can't use a 68060 at all.. Mac emulation
>> on the Amiga has to disable caches and hack MacOS ("OS8.x support" boxes
>> in SS) to get it to work even at all..
>
> there've been 060 cards for the Mac. no Apple Mac had 060 as standard, but
> a few 3rd party cards did arrive.
>
> they certainly know that their old 040 Quadra beat the doo-dah out of
> their PowerMac 601 ;-)
(again, a 33MHz Quadra outperforming a 60 or 90MHz 601 isn't a
difficult thing to do :)
Thanks
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