Pentium II and III: Brothers
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.
| 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 |
| SIMD | MMX (SSE) |
| 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.
