Bus Signal Timing and Input/Output Timing

Abstract

All operations within a computing system are controlled by means of a master clock oscillator. Depending on the design of the CPU, the oscillator may either be part of the CPU or it may be separate from it; for example, the Intel 8085 CPU has an on-chip oscillator while the Intel 8080 has a separate oscillator. The clock oscillator generates square wave pulses at precise intervals of time, the periodic time of the clock frequency being controlled either by means of an R-C circuit or by means of a piezo-electric crystal which is connected to the oscillator section of the CPU — see figure 3.1. The frequency of the master clock oscillator is typically in the range 1–20 MHz.