Information Technology - Computer Components and Information Processing Cycle Tutorial.
Computer Components are the main hardware structure of any computing device. As with most products, computers are designed in a variety of ways. There are however major similarities regardless of the brand (whether Dell, Gateway or IBM).
A Computer System accepts data as input, processes the data and provides same data as output. During this processing, the data must be stored. The processing is controlled by a sequence of instructions - the program - which is stored on the computer.
The basic components of a computer system is therefore:
1. Input devices,
3. Storage devices and
4. Output devices.
The image below is a schematic representation of a computer system component.
The computer needs input in some form to proceed with the next steps. Input and output devices are collectively called I/O devices. Input devices (and also output devices) are the hardware interfaces between the human user and computer system, but (as always) hardware is ‘driven’ by software, so when we talk about an I/O device, remember there is an associated ‘device driver’.
1. The Keyboard
This is the most common data entry device having more than 100 keys on it. Almost all general-purpose computers are supplied with a keyboard.
1. When you press a key, a number (code) is sent to the computer to tell it which key you have pressed. Keyboards are often used in conjunction with a screen on which the data entered are displayed.
2. The keys on a keyboard are usually arranged in the same order as those on a typewriter. This layout of keys is called QWERTY because Q-W-E-R-T-Y is the order in which the letters occur on the top row of the keyboard.
2. Pointing Devices
These are also called Cursor Control Devices. Cursor Control Devices are used to place the cursor (a highlighted screen location indicating where the next action will occur), select menu items, and control the computer by ‘clicking buttons’ on the screen. If these are built into the computer they are called Integrated Pointing Devices. A few such devices available are Mouse, trackpads, joystick, trackballs.
3. Pen Input Devices
These are based on screens that sense the location of a special pen that is connected to the terminal. Following are some of the devices:
1. Light pens either detect the monitor’s light or emit light that can be picked up by a specially designed monitor.
2. Styluses are pens with electronic point heads that activate pixels on the monitor, usually an LCD display.
3. Handwriting recognition software translates alphanumeric to digitized equivalents: normally these needs to be ‘trained’ to recognize an individual’s carefully printed letters, numbers, and symbols. These have been rather Primitive, but significant advances have been made recently. They are the primary input device of hand-held PDAs (Personal Digital Assistants) and PIMs (Personal Information Managers) state –of-the-art readers reportedly are very accurate.
4. Digitizing tablets are similar to light pens or styluses except one draws on a tablet rather than the screen.
5. The touch screen recognizes human touch and allows the selection of menu items displayed on a monitor by touching them.
4. Video-Input Devices
These comprise digital cameras, digital video cameras, and analog image converters.
5. Audio Input Devices
These comprise Digitized audio signals, Voice input and speech recognition.
6. Graphic Capture Devices
The bar code is a pattern of thick and thin bars divided by thick and thin spaces. Only the relative separations and thickness of the bars are important. Barcodes can be printed in different sizes and colors. The barcode is read either by passing a light-pen over it or bypassing the barcode over a flatbed scanner. Barcodes are suitable for data input when all that is necessary is to identify an item, and the data input simply comprises a code. The reading of the barcode records a transaction, and information is fed back to a computer database. Barcode systems are easy to operate and have very low error rates. Occasionally, a scanner can read a barcode number incorrectly. A check digit is included in the barcode number to reduce such incidents.
Magnetic Ink Character Recognition (MICR)
This input device is widely used by banks to process the tremendous volume of checks being received by them. This can be seen at the bottom of a check leaf, where some code numbers are written using special ink that contains magnetizable particles of iron oxide.
Magnetic Stripe Code
It is a short length of magnetic tape that may be stuck on the surface of a tag, card or document. On plastic cards such as credit cards, the stripe is usually sealed in. Stripes store data in the form of magnetic spots which represent the 1’s and 0’s of the ASCII code.
These have a memory store in the form of a very thin integrated circuit sealed into them. These can be used to store data about a customer, which can be updated as transactions are made using the card.
CPU is the main processing unit of a computer. The data given as an input to the computer is usually processed at the Central Processing Unit (CPU) using a device called Processor. It can be thought of as a collection of processing and storage units within an Arithmetic Logic Unit (ALU) and Control Unit (CU) that are linked internally and externally by busses that carry binary signals between. Higher the bandwidth or processing speed of CPU the faster the machine is. It comprises the Arithmetic Logic Unit (ALU), the Control Unit, Primary Memory(RAM, ROM, Cache Memory).
Output Devices are the means by which computer systems communicate with people. These devices accept data from the processor and convert them into the required output format. The convenience of the use of these devices and the quality of their results have a significant impact on the effectiveness of a computer system. In other words, output devices translate the data in the processor into a format that is suitable for people to use. Most ‘real world’ data is analog, i.e. it consists of continuous signals like sounds, pictures, voltage and so forth. These output devices are Visual Output Devices (Soft copy), Audio Output Devices (Soft copy), Hardcopy Devices (Print and Film), Computer Output Microfilm (COM).
Data Storage refers to the media and methods used to keep information available for later use. Some things will be needed right away while others won't be needed for extended periods of time. Therefore different methods of storage are appropriate for different uses. The RAM, ROM, earlier described as a part of the CPU, is the main memory of a computer. The main memory keeps track of what is currently being processed. These memory chips are the fastest, but most expensive, type of storage. It is volatile, meaning that turning the power off erases all of the data. They include Auxiliary Storage/Secondary Storage, Magnetic Disk, Magnetic Tapes, Optical Disks, Flash Memory, USB Drives, Removable Hard Drives, Smart Cards, Optical Cards.
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