Assignment in Microprocesor System

Microprocessor System

A control bus is (part of) a computer bus, used by CPUs for communicating with other devices within the computer. The control bus carries commands from the CPU and returns status signals from the devices, While the address bus carries the information on which device the CPU is communicating with. A data bus carries the actual data being processed, for example if the data is being read or written to the device the appropriate line (read or write) will be active (logic zero).

Step by step accessing of busses:

Read Cycle
	The steps involved in the read cycle are:
	CPU places address on address bus. Control signals memory - address on address bus is valid. Memory chip fetches data from location specified by the address and places on the data bus. Control signals CPU - data on data bus is valid. CPU takes data from data bus
	Write Cycle
	The steps involved in the write cycle are:
	CPU places address on address bus. Control signals memory - address on address bus is valid. CPU places data on the data bus. Control signals memory - data on data bus is valid. Memory chip takes data from data bus and places it in the location specified by the address.

A microprocessor has three basic elements. The ALU performs all arithmetic computations, such as addition, subtraction and logic operations (AND, OR, etc). It is controlled by the Control Unit and receives its data from the Register Array. The Register Array is a set of registers used for storing data. These registers can be accessed by the ALU very quickly. Some registers have specific functions - we will deal with these later. The Control Unit controls the entire process. It provides the timing and control signals for getting data into and out of the registers and the ALU and it synchronizes the execution of instructions.