Creating a wider bus using caching techniques

Abstract

The effective bandwidth of a bus and external communication ports can be increased by using a variant of data compression techniques that compacts words instead of data streams. The compaction is performed by caching the high order bits into a table and sending the index into the table along with the low order bits. A coherent table at the receiving end expands the word into it original form. Compaction/expansion units can be placed between processor and memory, between processor and local bus, and between devices that access the system bus. Simulations have shown that over 90% of all informative transferred can be sent in a single cycle when using a 32 bit processor connected by a 16 bit wide bus to a 32 bit memory module. This is for all forms of data, address, data, and instructions, and when a cache-based processor is used. >