The Logic Off Topic list

erkdemon wrote:
>--- In logic-ot@y..., TazmnianDv@a... wrote:
> 
>> I'm surprised that no one has mentioned the fact that PowerPCs are 
>more efficient than Pentiums, and accomplish more per clock cycle. I 
>think a 800 mhz mac is equivalent to 1.2 gig pentium. <
>
>It also depends on how the system is set up. 
>
>I think you'll find that people with fast recent PC's (or recently-
>upgraded PC motherboards) are getting appreciably more speed out of 
>their systems by using the new DDR system that lets you transfer data 
>to main memory at 266MHz.  

This is exactly the issue. When the fastest PCs were 33 MHz, their memory
bus was 33 MHz too. The RAM itself was a little slower than today's but the
bandwidth to memory was not anything like the bottleneck it has become as
the CPU clock speed has been racheted up by a factor of 30 (Macs) or  75
(33MHz 486 -- 2.53Ghz P4) while memory speed has only tripled or quadrupled
in the case of current Macs ( SDRAM) or by a factor of 11 to 15 for the
fastest PCs (PC1066 RDRAM or 333 DDR). While caching helps keep the CPU
stoked with data and instructions up to a point,  in applications like ours
(eg- audio plugins where the output stream of a Plugin (eg Platinum Verb)
needs to be sent out to main memory) the memory bandwidth is a large factor
in determining the number of plugins which can be run on a given CPU. 

Hardware sites have reported that performance doesn't scale well with CPU
speed as Athlon's and P4s are clocked higher  and  higher unless still
faster memory architectures are employed. Look at the way the first 845
chipsets for the P4 which used PC 133 SDRAM hobbled its performance. 

If you look at the plethora of DDR chipsets for Athlon and P4 coming out of
SIS, VIA, AMD, Intel and NVidia you can't help wondering how hard it can be
to provide support up to date memory architectures.

Regards,
M