CO Hardware System

In the previous lesson, you were introduced to the computer organization. You learned about system hardware and main components that make a computer system and software layer to help a user interact with the computer system. In this article, you will learn about the hardware part of the system in more detail.


The system hardware consists of following at a minimum.

  1. Keyboard
  2. Display
  3. Printer
  4. CPU Board
  5. Memory Board
  6. I/O Board

The keyboard, display and printing devices need an interface to interact with the system and I/O board provide that interface for communication.

System Organization Overview
System Organization Overview

Keyboard generates ASCII codes for a system and by looking at the codes from the keyboard the CPU knows what the character is. The communication with the CPU and devices must be standardized and uniform. That is why all modern systems have device controllers so that the details of the device is hidden from the system.

System Hardware

There are many types of devices available today. You will find a variety of printers, display devices, newer CPUs and upgraded memory and storage units. All these variations in devices are handled by the I/O interface provided by the system.

Printer Types

  1. Dot Matrix
  2. Laser
  3. Daisy Wheel
  4. Inkjet

Display Device Types

  1. Raster Scan
  2. Random Scan
  3. Calligraphic
  4. Vector Display
  5. Point Plot

CPU Boards

  1. Control Applications
  2. Data Processing

Note: They both are different because their processing inputs are different.

Memory Boards

When you think of memory, consider following.

  1. Speed
  2. Cost
  3. Size

The high speed memory effect the size and the cost. The cost of high speed memory is high and size is less. The cost per bit of storage is higher near CPU and less near hard disk.

The following diagram shows the memory hierarchy.

Memory Hierarchy
Memory Hierarchy

Let us give a small summary of different types of memory.

SIZEKbytesMBytes100’s of MB
SPEED10 nsecs100 nsecs2 – 10 milli-secs

Technology classification of Memory

  1. Dynamic RAM – It is a slower RAM than static.
  2. Static RAM – It is a faster RAM.

Technology classification of Storage.

  1. Hard Disk
  2. Floppy Disk
  3. Tape Drive

Storage also need I/O interface to communicate with the system. The system inputs are already stored in files and output from system is stored in these files again.

Classification of I/O interface

You can classify I/O interface into two.

  1. Device Electronics
  2. Device Controllers

As part of Operating system, there will be IO routines and software called device drivers.

Networked Computers

You must ask this question – Why do we have networked computers?

There are only three reasons for a computer to establish a network.

  1. Establish communication among users.
  2. To share some resources.
  3. For remote access.

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