Memory and Storage

Abstract

In Chapter 5 we skirted around the idea of long-term memory much like we did with the idea of computation and the ALU. This was an attractive option at the time because it meant we could focus on the processor itself, but the concept of memory and storage is of course central to the operation of the processor: everything it does is oriented toward computation on (large numbers of) values we must store somewhere if the program being executed is not trivial. To examine these issue in more detail, in this chapter we investigate the design and implementation of a range of memory and storage devices focusing on those most pertinent to processor design. Specifically, we include registers and main memory already discussed previously, describing in basic terms how they can be modelled in Verilog. Ultimately, our goal is to build a memory hierarchy capable of supplying data and instructions to our processor data-path via a standard mechanism; to achieve this efficiently and robustly we include an investigation of cache memory and issues such as error correction.