RE: [TCLUG:607] Mixing Alphas and x86s

[Brad DeJong <1796@mn3.lawson.lawson.com>]

Minor point of contention.  The 21066 is slower than the 21064.  The   
processor core is the same.  The main difference is that the 21066   
integrated PCI and memory control logic which made it very easy to design   
motherboards for the chip.  It was also fairly low cost since no PCI and   
memory control support chips were needed.  Unfortunately, to find space   
for the extra logic (or was it I/O pins?), DEC reduced the memory path   
from 128 bits to 64 bits.  This killed performance on any memory   
intensive tasks, in particular, many of the floating point intensive   
problems that the Alpha excels at were negatively affected.  This   
resulted in very mixed reports of Alpha performance.  Some users felt   
that their 166 MHz 21066 was faster than a Pentium 200, while others   
reported performance similar to that of a Pentium 90.  The UDB's were the   
most common unit that used the 21066.  Available speeds were 166 MHz and   
233 MHz.

The current "low cost" Alpha, the 21164PC, makes a similar trade-off, but   
rather than reducing memory bandwidth, it omits the on-board L2 cache.   
 Since the on-board L2 cache is only 96 KB, this only affects a small   
number of programs where the working set of instructions and data fits in   
96 K.  Some benchmarks (STREAM results for example) actually report that   
the 21164PC is faster than the 21164A.  Not having to check the extra   
level of cache on cache misses for programs that have a lot of cache   
misses improves performance.

Probably more than anyone wanted to know, but when you're obsessive   
compulsive like me, silly details matter.

alpha processor models
21064, oldest, fairly slow per mhz
21066, step up.. still kinda slow
21164, current wide available CPU.. very fast
21264, still in beta *AFAIK*  will beat the pants off of a PII :)