• Abstract and Figures
• Public Full-text

Standard Grade Computing Studies C o m p u t e r Syste m s Faculty of Business Education and ICT 1. Foundation What is a computer? A computer is an information-processing machine. That means the it takes in raw information, makes some changes to it, and then puts the information back out in a new more useful form. This is called input, process, output (or I.P.O. for short). Information that is processed and stored by a computer is called data. This means that when we know the structure and meaning of the data it is called information. Everything that goes on in the world can be thought of as input, process, and output. For example, brushing you teeth! Input Process Output Toothpaste and Cleaning Clean teeth + fresh Brush Teeth breath Figure 1 - I.P.O. – Input, Process, Output What makes a computer work? A computer must have a processor (a brain) and memory (so that it can remember the programs and data that it is using). It must also have an input device (a way of putting information into the computer) and an output device (so that the computer can show us what it has done). Finally a computer needs backing storage. Backing storage is where the computer puts all its programs and data when it is not using them. Data that needs to be saved for another day is written on to backing storage. When this data is needed again it is read from backing storage. How does all this fit together? Here is a diagram of a basic computer system. Central Processing Unit Main Memory Input Devices Output Devices Processor Data Flow Backing Storage Figure 2 - Simple block diagram of a computer system with arrows showing how data flows between parts of the system. ALL SAINTS RC SECONDARY SCHOOL FACULTY OF BUSINESS EDUCATION AND ICT Main Memory and processor together make up the Central Processing Unit or CPU. The CPU is the brain of the computer because, like our brain, it contains both processor and memory. The part that thinks is the processor and the part that remembers is the memory. The CPU controls what happens to all the devices connected to it and carries out all the instructions held in programs. An input device allows the user to communicate with the CPU and the CPU uses an output device to show the user what it is doing. Programs and data are loaded from backing storage, when needed, and are stored in memory. What is memory? Computer memory is very much like our own. When the computer is working all the programs and data that it is using are stored in memory. The computer has two different types of memory. • Read Only Memory or ROM The computer can only read this kind of memory. The computer cannot put any data into ROM. The computer uses ROM as a library where it can find important programs and data. These programs and data are built into the ROM chip when it is made. • Random Access Memory or RAM This kind of memory can be read from and written to. The computer uses RAM to store programs and data that it has loaded from backing storage or received from an input device. RAM stores data for as long as the computer is switched on. When the computer is switched off, all the data in RAM is lost. This is why we use backing storage to keep programs and data when they are not being used. Types of Computers There are a number of different computer types. These computers are designed to do a range of different jobs. Microprocessor A microprocessor is a specialised electronic circuit or chip which can perform certain operations. Microprocessors can be found in many household appliances as well as in all computers. For instance the microprocessor in your Washing Machine would be used to control the machine by executing the wash programs (e.g. when to spin, add powder etc.). ALL SAINTS RC SECONDARY SCHOOL FACULTY OF BUSINESS EDUCATION AND ICT Figure 3 - A microprocessor chip All computers are made up of different types electronic chips and some of these chips are microprocessors. Desktop A desktop computer is personal computer that can fit on a user's desk and perform business-computing tasks. Also, especially if linked to a network of other computers, it may be referred to as a workstation Desktops are the most common type of computer. Figure 4 - Desktop Computer Laptop/Notebook A laptop computer (also known as notebook computer) is a small mobile personal computer, usually weighing around from 1 to 3 kilograms (2 to 7 pounds). A laptop computer is small enough to sit on your lap. The laptop computer's small size allows you to take it almost anywhere and access the Internet. Laptops usually run on batteries and have a clam-shell constructions which allows them to be opened for work or closed. Figure 5 - Laptop Computer Palmtop Personal digital assistants (PDAs or palmtops) are handheld devices that were originally designed as personal organisers, but became much more versatile over the years. A basic PDA usually includes a clock, date book, address book, task list, memo pad and a simple calculator. One major advantage of using PDAs is their ability to synchronize data with desktop and laptop computers. Figure 6 - A Palmtop being used ALL SAINTS RC SECONDARY SCHOOL FACULTY OF BUSINESS EDUCATION AND ICT Hardware Devices Now you will look at some of the different devices that we plug into a computer to allow the computer to do a useful job. There are three different types of device: input, output and backing storage. • Input devices let you give information and instructions to the computer. • Output devices let the computer show or give you the answers to your instructions. • Backing storage devices let you to save all the programs and data used by the computer. You can also load programs and data from backing storage when they are needed. Input devices Figure 7 - Typical computer keyboard Keyboard The keyboard is made up of lots of keys that, when they are pressed, they cause a certain signal to be sent to the computer. This signal tells the computer which key on the keyboard has been pressed. A keyboard is the most common form of input device. Mouse Figure 8 Two-button mouse This is a simple input device that is used along with a keyboard. The mouse moves an arrow or pointer around the screen. As the mouse moves around the top of the desk, the arrow on the screen moves also. You use the mouse to point to things on the screen and then select them using one of the buttons on the top of the mouse. A mouse is often used with graphical data such as drawings or graphics on screen. ALL SAINTS RC SECONDARY SCHOOL FACULTY OF BUSINESS EDUCATION AND ICT Trackball A trackball is really like an upside down mouse. Instead of moving the mouse around the desktop, you move a little ball that is inside a casing. You move the ball using the palm of your hand or your thumb. When the ball is moved, the pointer moves across the screen. Like a mouse, a trackball is often used with graphical data such as drawings or graphics on screen. Many laptop computers used a trackball because it takes up less space than a mouse. Graphics Tablet This device is often used along with specialised software such as Computer Aided Design systems. The tablet has a section which lists all the commands available and has a flat panel on which a digitiser can be moved. The digitiser is similar to a mouse in that it has buttons which can be pressed to make selections. However there is no rolling ball. The tablet detects the position and actions of the digitiser and passes this information to the CPU. For example, a plan of a house needs to be input into a computer. It would cost a lot of time and money to enter the plan from scratch into the computer. Instead, the paper version of the plan can be placed on the flat bed of the graphics tablet and the digitiser can be moved to all the important points on the plan (corners, walls etc). In this way, the whole plan can be transferred to the computer in a very short space of time. Touch sensitive screen This is a type of display screen that has a touch-sensitive panel covering the screen. Instead of using a pointing device such as a mouse or light pen, you can use your finger to point directly to things on the screen. Although touch screens provide a natural way for users to act with computers, they are unsatisfactory for most applications because the finger is really to big for this task. It is impossible to point accurately to small areas of the screen. Also most users find touch screens tiring to the arms after long use. Joystick A joystick is a computer device consisting of a handheld stick that moves about one end and transmits position to a computer. They are often used for computer games or to control devices for disabled people such as wheelchairs. Trackpad A touchpad is an input device commonly used in laptop computers. It is used to move the cursor, using the movement of the user's finger. A trackpad is a substitute for a computer mouse. Trackpads vary in size but are rarely made larger than 50 cm². ALL SAINTS RC SECONDARY SCHOOL FACULTY OF BUSINESS EDUCATION AND ICT Output Devices VDU The Visual Display Unit is another common form of output device.

Load more

  39

Copy Link