This was the very first 6th generation CPU for the x86 market.
Intel was really ahead of everyone with the processor with the codename
P6. New with this processor was the the RISC design of the core. All CISC
instructions from the software were translated into RISC instructions
which could be calculated more efficiently. NexGen was the first to implement
this in their Nx586 and Intel used a similiar process in their P6 core.
The performance at 32bit was very good and the integrated level
2 cache which ran at the same speed as the core made it an exceptional
performer....at 32bit! Unfortunately the P6 was too far ahead of its time.
At the end of 1995 when the Pentium Pro was introduced, most software
was 16bit and even the new version of Windows, Windows95, was 16bit. The
performance of the 32bit optimized Pentium Pro at 16bit was slower than
that of a Pentium Classic.
Another disadvantage of the Pro was the very very manufacturing costs.
The integration on the level 2 cache was the reason for this. Only after
the cache and the core were installed in the chip package, Intel could
test it. If either the cache or the core was faulty, the whole chip was
useless. The chip also used a new socket, the 387 pin Socket8 and a new
The bad 16bit performance, high price and the use of a new socket
and chipset made that it never was a succes as a desktop processor. It
was however the best x86 CPU for NT servers for a long time. This was
to be the domain of the Pentium Pro, the Pro's GTL+ bus of the Pro made
it possible to use up to four CPU's on one board. If you needed multiprocessor
power the Pentium Pro was the processor to have. Typical use for the Pentium
Pro was in large file servers and database servers.
Packaging of the Pentium Pro was in Dual Cavity PGA for the 256
and 512KB cache versions and Dual Cavity PPGA for the 1MB cache versions
which was introduced in August 1997. The P6 core had no MMX, 16KB level
1 cache and operated with a 60 or 66 MHz bus. Manufacturing was at 0.50µ
and 0.35µ, the transistor count with the cache was at that time
As a reference; the Pentium Classic had 3.100.000 transistors
and the Pentium MMX had 4.500.000 transistors.
Socket8 was a dead end as there was no further development in
that area. Intel did release an overdrive processor for the Pentium Pro,
which was a Pentium II on a small PCB with a Socket8 interface.
The Pentium Pro was the first processor to use the P6 core but
surely not the last. The Pentium II & III, the Celeron and the Xeon
were all based on the P6 core. After a troubled start the P6 became Intels
biggest success story!
Available models :
PentiumPro 150MHz (P6, 80521), 256KB L2 cache, 2.5 x 60MHz
PentiumPro 166MHz (P6, 80521), 512KB L2 cache, 2.5 x 66MHz
PentiumPro 180MHz (P6, 80521), 256KB L2 cache, 3.0 x 60MHz
PentiumPro 200MHz (P6, 80521), 256KB L2 cache, 3.0 x 66MHz
PentiumPro 200MHz (P6, 80521), 512KB L2 cache, 3.0 x 66MHz
PentiumPro 200MHz (P6, 80521), 1024KB L2 cache, 3.0 x 66MHz
Intel Pentium Pro Pictures