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Pentium II and III: Brothers

Intel's 15 Most Unforgettable x86 CPUs

Released in 1997, the Pentium II was an adaptation of the Pentium Pro aimed at the general public. It was quite similar to the Pentium Pro, but the cache memory was different. Instead of using a cache at the same frequency as the processor (which is expensive), the 512 KB Level 2 cache operated at half-frequency. In addition, the Pentium II abandoned the classic socket for a cartridge containing the processor and the Level 2 cache, which was in the cartridge and not on the motherboard or in the processor itself.

New features compared to the Pentium Pro were essentially MMX (SIMD) support and a doubling of the Level 1 cache. The first Pentium III (Katmai) was very similar to the Pentium II. Released in 1999, its new feature was essentially support for SSE (SIMD instructions), but the rest was identical.

Intel Pentium II and III
Code name Klamath (Pentium II 0.35µ), Deschutes (Pentium II 0.25µ), Katmai (Pentium III)
Date released 1997, 1998, 1999
Architecture 32 bits
Data bus 64 bits
Address bus 36 bits (32 bits on the P III)
Maximum memory 64 GB (4 GB on the P III)
L1 cache 16 KB + 16 KB
L2 cache external, 512 KB (1/2 CPU frequency)
Clock frequency 233-300 MHz (Klamath), 300-450 MHz (Deschutes), 450-600 MHz (Klamath)
FSB 66-100-133 MHz
FPU built-in
Fabrication process 350 nm (Klamath), 250 nm (Deschutes, Katmai)
Number of transistors 7,500,000 + cache (Pentium II), 9,500,000 + cache (Pentium III)
Power consumption 25-35 W
Voltage 2.8 V (0.35µ), 2 V (0.25µ)
Die surface area 204 mm² (0.35µ), 131 mm² (0.25µ), 128 mm² (PIII) + cache
Connector Slot 1

The Pentium II and III had 512 KB of Level 2 cache (31 million transistors). One Pentium II actually had an on-chip 256 KB Level 2 cache—the Pentium II Mobile Dixon. Using a 180 nm fabrication process, this processor was significantly faster than the desktop versions.

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