• Integration of L2 cache on the processor
• L1 cache size increased
• Multi-Processor support
• Built into ATX form factor motherboards
• Three internal instruction pipes

Intel MMX technology

One of the outstanding features of the Pentium II processor is the incorporation of Intel MMX technology - Intel's most significant enhancement to the Intel architecture in the last ten years. While the Pentium II's MMX tecnology is binary compatible with that used in the Pentium processor, it is also combined synergistically with the Pentium II processor's advanced core architechture. Powerful MMX technology instructions take full advantage of the efficient processing techniques of Dynamic Execution.

Integration of level 2 (L2) cache on the processor

Another fine feature of the Pentium II processor is the L2 cache that is integrated into the processor. By incorporating the L2 cache and removing it from the motherboard, the cache scales with the processor core frequency, rather than running at typical motherboard bus speeds of 60 or 66 megahertz (MHz). With the core at 266 MHz, the cache bus runs at 133 MHz, twice the speed of a Pentium processor's cache access. Along with the integration, the L2 cache features its own separate internal 64-bit backside bus, which does not share time with the external 64-bit bus used by the CPU. The integration of the L2 cache into the processor also makes motherboards less costly to manufacture and sell. This decrease in production cost is a direct result of no longer needing the fast speed, 15 nanosecond (ns), very expensive static RAM (SRAM); the SRAM is extremely costly.

L1 cache size increased

The Pentium II processor also includes 32 kilobytes (KB) of L1 cache, 16 KB data, 16 KB instruction, twice that of the Pentium Pro processor.

Multiple processors

The Pentium II provides support for up to two processors. This enables low-cost, 2-way symmetric multiprocessing, providing a significant performance boost for multi-tasking operating systems and multi-threaded programs.

Built into ATX form factor motherboards

Pentium II motherboards will almost exclusively be PCI and ISA bus-based along with a new Chipset. The layout, or form factor, of the motherboard is different from the Baby-AT form factor used in Pentium, P5, and some 486 models. The ATX form factor is about the same size as the Baby-AT, but the board is turned 90 degrees from the way the Baby-AT boards mount. This puts the long side of the board against the back of the case with the expansion slots parallel with the short side of the board. The main reason for the new form factor is to move the CPU to an area where expansion cards are not located and allow for much better cooling since it mounts right next to the external fan on the new ATX power supplies.

Three internal instruction pipes

The Pentium II includes three internal instruction pipes that can execute multiple instructions in one clock cycle. The Pentium II can execute instructions out of order and also incorporate dynamic branch prediction and speculative execution capabilities.