A 2000-MOPS embedded RISC processor with a Rambus DRAM controller

Abstract

We have developed a 0.25-/spl mu/m, 200-MHz embedded RISC processor for multimedia applications. This processor has a dual-issue superscalar datapath that consists of a 32-bit integer unit and a 64-bit single-instruction multiple-data (SIMD) function unit that together have a total of five multiply-adders. An on-chip concurrent Rambus DRAM (C-RDRAM) controller uses interleaved transactions to increase the memory bandwidth of the Rambus channel to 533 Mb/s. The controller also reduces latency by using the transaction interleaving and instruction prefetching. A 64-bit, 200-MHz internal bus transfers data among the CPU core, the C-RDRAM, and the peripherals. These high-data-rate channels improve CPU performance because they eliminate a bottleneck in the data supply. The datapath part of this chip was designed using a functional macrocell library that included placement information for leaf cells and resulted in the SIMD function unit of this chip's having 68000 transistors per square millimeter.