Computer Hardware

Dell Hybrid PCNot everyone today knows the basics needed to understand use of computers for communications and information technology applications in education, at work, in social life, etc. These notes give a very simplified explanation of the most basic concepts.

What computers are and are not
The term 'computer' is misleading for many people. It suggests that these machines are mainly about computing with numbers; that was their original use, but they are in fact 'all-purpose' machines. A computer can work as a telephone, a television, a VCR, a CD player, a typewriter, a bulletin board, a post office, a multimedia textbook, a mini-library, an art gallery, a music-composing tool, etc. You can use it to design a house, create a 3D painting, simulate a science experiment, and, yes, even compute with numbers. Most uses of computers in education today do not involve numbers at all

How a computer works
The brain of the computer is called the Central Processing Unit (CPU). It is located inside the main box on a printed electric circuit called a Motherboard; it is a 'micro-chip', a piece of ceramic-like material that has billions of microscopic electrical connections attached onto it. Any form of information (words, pictures, sounds, and numbers) can be converted to electric signals that are 'input' to the chip. The electric connections on the chip allow these signals to be compared to one another and combined with one another according to a 'program' that 'processes' or manipulates the information into a new form, which becomes the 'output' electric signal from the chip. Everything else in a computer is designed to take human information and convert it to the input electric signals for the chip, or to take the chip's output signals and convert them back to a form that humans can recognize. These other components are called 'peripherals', or just input and output devices.

The parts of the computer
What you see when you look at a typical computer workstation is:

  • a Monitor -- looks like and basically is a TV screen and controls
  • a Keyboard -- like a typewriter but with many useful extra keys
  • a Mouse -- a palm-size gadget that rolls on a ball and has buttons on it
  • a Printer -- inkjet or laser or dot matrix
  • a pair of stereo Speakers, for multimedia systems (also sometimes a Microphone to speak into)
  • a miniature TV camera
  • the BOX -- contains the CPU microchip and all the really important components

So then, what's in the BOX?
In the Front of the box:

  • On/Off switch (sometimes on the side)
  • Reset button -- only on some machines
  • Floppy-disk Drive -- you put in a square disk that contains information
  • CD-DVD drive -- you put in a digital CD platter that contains a lot of information
  • Tape Drive -- optional, for storing information in case something goes wrong
  • Other special drives -- old-fashioned big diskette drive, super-new storage drives
  • On/off light, Hard Disk Operating light, miscellaneous lights and buttons

Inside the Box. What you see on the front is just the opening slot of the actual drives. A 'drive' is a storage device. In addition to the CPU chip and the input and output devices, computers need places to store information either temporarily or more permanently (for reuse later), the short-term storage is called RAM (random-access memory).

  • The CPU and RAM memory chips on the 'motherboard'
  • The HARD DRIVE -- the main long-term storage system for programs and info
  • The Disk and CD-ROM drives -- the main part of them is inside the box
  • The specialized 'Boards' -- these run the input and output devices
  • The Modem -- one of the boards; connects to the telephone line
  • Network Board -- another board, connects to the LAN (see below)
  • Video Board -- connects to the monitor
  • An electric power supply, battery, and a lot of connecting cables

Every input device and output device is connected first to a specialized board that has its own microchip to convert signals and pass them on to the CPU (on the main or Mother Board).

Hybrid PC Back

In the back of the Box. This is where all the input/output peripherals are connected to the Box, and the Box is connected to the electric outlet, the telephone system (for a modem), and the local area computer network (LAN) cable system. There are a lot of confusing cables back here. Sometimes they come lose. The specialized Boards stick out the back slightly, just like the drives stick out the front slightly. The Boards have connector sockets called Ports where the keyboard, mouse, printer, monitor, etc. are supposed to be plugged in.

The 'Boot Up' Process
Now the machine starts to check all the different input and output devices. It looks for the keyboard and tests it, the mouse, the monitor, the printer, the hard drive, the disk drive, the CD/DVD drive, etc. For each of these it loads a program called a 'driver' program to convert signals between the CPU and the device. This is the time when the machine detects any problems. Hope that it doesn't find anything wrong! This is also usually the time when a program is run automatically to check for 'viruses' (these are unwanted programs that can damage the machine or make it not work properly; they have nothing to do with biological viruses at all).
If everything is working, the machine displays the USER INTERFACE. This is your signal that you can now take over and tell the machine what to do. Everything before this was automatic, run by programs built into the machine. The basic startup program is called the BIOS, then there are other programs that you can sometimes change (like how to check for viruses, what kind of CR-ROM drive you have, etc..

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