(October 17th 1994) Motorola and IBM announced today that the first
64-bit PowerPC processor - the 620 has hit first silicon. It is
expected to begin general sampling in the second quarter of 1995 with
general availability set for the second half of 1995.
The chip will initially ship running at 133MHz and the companies have
taken the unusual step of specifying a maximum clock-speed design
point: 150MHz. At 130MHz the estimated SPECint92 for the processor is
225 and the SPECfp 300. These results are for 32-bit code and the
companies say that they would not expect to see a significant speed
increase under the 64-bit mode. The single-chip processor contains 7
million processors, though a good proportion of these are used in the
64kB cache; split evenly between data and instructions.
Die size is 17.1mm x 18.2mm and programmers will be able to keep
their toes warm in the long, dark winter evenings since the thing
dissipates a toasty 30W at 133MHz.
Perhaps the most surprising thing about the processor is the lack of
a radical design change. It looks very much like an evolution of the
604. For example the 620 has exactly the same number of functional
units as the 604 - three integer units (one for complex math) one
floating point unit, a branch unit and a load/store unit. The chip
can fetch and dispatch up to 4 instructions per cycle. A little of
the 620's extra speed comes from a slightly faster transistor design,
but most comes from the extra cache and a general clean-up of the
functional units. The L2 cache controller has also come on-board the
processor and the designers have allowed for a massive cache capacity
configurable from 1MB to 128MB. There has also been a substantial
design push to enhance multiprocessor support, with a new method of
decoupling processing from the need to check cache-coherency on other
processors. All in all, the designers say that this is a chip
designed for fast transaction processing in mind.
Meanwhile IBM has announced availability and pricing for its 100MHz
PowerPC 601, 100MHz PowerPC 604 and 66 and 80MHz PowerPC 603
microprocessors.
The 604 is sampling now and the company says it expects to begin full
production in December.
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