Introduction

The AMD-K6 processor implements advanced design techniques known as the RISC86 microarchitecture. The RISC86 microarchitecture is a decoupled decode/execution design approach that yields superior sixth-generation performance for x86-based software. This chapter describes the techniques used and the functional elements of the RISC86 microarchitecture.

AMD-K6® Processor

■ Advanced 6-Issue RISC86® Superscalar Microarchitecture

◆ Seven parallel specialized execution units

◆ Multiple sophisticated x86-to-RISC86 instruction decoders

◆ Advanced two-level branch prediction

◆ Speculative execution

◆ Out-of-order execution

◆ Register renaming and data forwarding

◆ Issues up to six RISC86 instructions per clock

■ Large On-Chip Split 64-Kbyte Level-One (L1) Cache

◆ 32-Kbyte instruction cache with additional predecode cache

◆ 32-Kbyte writeback dual-ported data cache

◆ MESI protocol support

■ High-Performance IEEE 754-Compatible and 854-Compatible Floating-Point Unit

■ High-Performance Industry-Standard MMX™ Instructions

■ 321-Pin Ceramic Pin Grid Array (CPGA) Package (Socket 7 Compatible)

■ Industry-Standard System Management Mode (SMM)

■ IEEE 1149.1 Boundary Scan

■ Full x86 Binary Software Compatibility