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SPECMARKS SLIP AS ALLIANCE UNVEILS 120MHZ AND 133MHZ 604

(June 19th 1994) IBM and Motorola have announced 120MHz and 133MHz
versions of the PowerPC 604. No pricing has been given and volume
production has been set vaguely for some time in the second half of
the year.

The big news, however is that the companies seem to have
significantly over-estimated the integer and floating point
performance of the processor. Originally the 100MHz part was
estimated to have a SPECint of 160 and a SPECfp of 165. Things were
scaled back a bit last week with the announcement of the new versions
- the 120MHz part was estimated to have both integer and floating
point SPEC ratings of 180, while the estimated figure at 133MHz was
200MHz.

However actual measured figures for the new IBM RS/6000 models show
the processors falling short of expectations. The also show the
extent to which it is unwise to assign a SPECmarks to a chip, rather
than an entire machine.

The new low-end RS/6000 43P machine shows a 100MHz 604 with 256k of
async level 2 cache producing SPECint 128.1 and SPECfp 120.2.
Doubling the size of the cache and making it synchronous improves the
figures to SPECint 140.8, SPECfp 129.1

At 120MHz, and with the 512k cache the machines manage Specint 157.9
and SPECfp 139.2.

The speediest, 133MHz part is measured at SPECint 176.4 and SPECfp
156.5.

In summary, a 133MHz 604-based machine is carrying out floating point
operations slower than the alliance suggested a 100MHz chip would,
while integer figures at 133MHz are worse than we were lead to expect
last week from the 120MHz part. It's also worth noting that the
integer scores are consistently better that the floating point
figures, again a change from the expected results.

It's not all gloom for the PowerPC camp; IBM quotes Pentium figures
from Intel that shows the machines running 20% faster than a
comparable Pentium-equipped box chip at the same clock speed, while
floating point is 40% better. The quoted figures for a 133MHz Pentium
is SPECint 147.5 and SPECfp 109.6

There are two possible explanations for the discrepancy between the
estimated and measured figures: either the alliance's estimating
methodology is out of kilter, or IBM's machines simply don't do
justice to the 604's raw performance. The former would be something
of a blow to the alliance which has made much of its conservative
estimates in the past. The latter will not be too palatable to the
Power Personal Systems division at IBM. More details on this in the
next issue.

As for the next stop, IBMers say that 150MHz and 180MHz versions of
the 604 are planned, but no timescales were given. Motorola is the
one member of the alliance that has yet to announce machines using
the 120MHz or 133MHz processors.


 

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