6 - Semiconductor memory

Abstract

This chapter examines the use of random access memory (RAM) and read only memory (ROM) within the PC. It also explains how one can locate and replace a faulty memory chip. Each location in semiconductor ROM and RAM has its own unique address. Each ROM and RAM accounts for a particular block of memory depending upon the capacity of the ROM or RAM in question. The BIOS ROM that contains the low-level code required to control the system's hardware is programmed during chip manufacture. Computers work by executing instructions from RAM so the speed of RAM is a very important factor in the performance of the whole machine. Dynamic RAM (DRAM) is the oldest type that stores each bit in a storage cell as an electrical charge, which must be refreshed every few milliseconds to retain the information. Extended data out RAM (EDO RAM) is faster than DRAM and extends the time that output data is valid.