Ram Random Access Memory RAM is the area that is used for holding the programs and their data while the computer is working with them. RAM means the memory can be read from and written to randomly. These sets of programs perform the most basic control and supervisory operations for the computer.
But the storage devices are not as fast as the CPU. Most of the time the CPU has to slow down because of these devices. A small section of the high speed RAM is used to keep frequently needed information. So, one need some storage device to store data and other information. It should be cheap and should not lose the content when power is switched off. This storage is called as the secondary storage. All secondary storage devices act both as input and output devices.
Magnetic storage media fulfils these requirements and most common storage devices are disks and tapes. Floppy Disk It is the most common storage media and it helps transferring the data from one computer to another. Data is stored in these sectors. Each piece of data that is stored, has a track number, a sector number and side number as an address. So data can be accessed randomly from anywhere on the disk.
Hence, it is also called as Random Access storage. The most significant difference between a floppy disk and a hard disk is that the hard-disk is completely sealed and is protected from dust and airborne particles. The name hard disk comes from the rigid platter that is inside the drive. This is, often called by different names like fixed disk or Winchester disk.
The hard disk comes in different shapes. Most hard disks nowadays store something close to MB. Magnetic Tapes Apart from using disks for external storage purposes, magnetic tapes are also used for storing large amount data.
The magnetic tape could be a large reel or a small cassette. The tape is essentially a plastic ribbon coated with some material that can be magnetized. The data is recorded on these magnetic spots. The data on the tape can however be read or written sequentially only. Hence, it is called as sequential access storage. The computer bus consists of two parts, the address bus and a data bus.
The data bus transfers actual data, whereas the address bus transfers information about where the data should go. VDUs can work in two different modes viz. Text mode and graphic mode. In text mode, the screen is divided into a matrix of rows and columns; each cell of the matrix is used for one character.
A typical screen has 80 character positions per line and 25 lines across the screen. In graphic mode, the screen is treated as an array of tiny dots called pixels. The characters and pictures that appear on the screen are shown by making a drawing of these pixels.
The number of dots on the screen is called as resolution. The higher the resolution the better the picture. A typical high resolution monitor has x pixels across the screen. The formation of images on the screen is handled by the Video Controller. The Video Controller along with the memory that holds the display- data are together referred to as display adaptors. Though these details do not affect you as an end user, it completes your knowledge of the computer.
System Unit It is a box like structure of the computer. Inside this box you can find the power supply, storage device, hard disk and floppy drives, and the motherboard containing CPU and memory.
It can also contain optional cards like the modem card, mouse card, video card, sound card. System unit or Main unit or Console comes in two styles. Desktop model and Tower model. Hard disk activity indicator: this gives the information as to whether the hard disk is being accessed read from or written to or not. Power switch Depending on the model of the computer, power switch can be anywhere.
Reset switch Pressing this switch restarts your computer, your power supply. The entire design of the PC is based on this chip. The performance of CPU depends on the model, version and speed. Model Each CPU has a specific model number assigned to it. Given below is the list of common CPUs produced by Intel Company in an increasing order of their power, speed and performance.
Speed The speed is measured in Megahertz. Higher the value, faster is the information processed by CPU. The clock provides the timing signals in the form of pulses that are used by the computer components to synchronize their work.
The clock chip uses a quartz crystal. The speed of the clock is measured in MHz. Speed of Operation Speed of a computer can be assessed either in terms of the processing capacity of the microprocessor or by the speed of the computer which is measured in MIPS Million Instructions Per Second. The Memory The internal memory of the PC is in the form of chips. The Bus Communication between the microprocessor, the memory chips, and another chips found on the motherboard is accomplished a set of wires running between them.
This set of wires is called the bus. The Ports As in human terminology, ports are used to receive and send goods. These ports could be serial or parallel. A serial port, is one where eight bits queued up and sent bit. In the parallel port all the eight bits are transferred simultaneously. The Storage System The hard disk drive and floppy diskette drive are also mounted in the system unit.
The Start-Up Process Every time a computer is switched on, it goes through a series before the user is permitted to interact with it. These instructions are called the power on self-test POST program. The POST checks the entire RAM area and tests the connections to the various hardware devices attached, like the keyboard, the disk drive, etc. Now the computer waits for the operating system to take over. The bootstrap loader first checks the A drive for a bootable disk. A disk that has the Operating System is a bootable disk.
If the disk in that drive is not bootable, errors are reported. If the floppy is not there in the drive, the hard disk drive is checked. This process of loading or copying the operating system is called booting. This is known as a soft boot. Using the reset switch or switching off and then switching on the computer is known as a hard boot. Connecting your Computer You must first comprehend the two main steps needed to get your PC working.
Keyboard, mouse, and printer to the system unit. Before making connections, make sure that the power supply to the PC, printer and monitor is off, Connecting your system while the power is on may cause permanent damage to the computer and its peripherals. The position of the keyboard socket on your system may be different. Before inserting the cable, make sure that the pin in the cable are lined up with respect to the holes in the connector. Make sure the keyboard plug is firmly fitted in the keyboard socket.
Monitor-System Unit Connection Monitor has two cables. One is connected between the monitor and computer, referred to as the video cable. The other cable is connected between monitor and power socket called the power cable.
The power outlet may be present on the rear panel of the system unit, in which case the power plug must be connected to this outlet. Otherwise, it should be connected to the main power supply. The video cable will go into the respective socket only. Mouse-System Unit Connection The rear panel of a system unit has both serial and parallel ports. You will have to connect it accordingly. Connecting a mouse to the machine is not enough.
A dedicated program called the Driver which comes with the mouse has to be executed as per installation procedures given in the accompanying manual. Printer-System Unit Connection Printer unit has two cables. One is connecting the printer to the computer and another connecting it to the power supply. Printers are of two types: - Serial and Parallel. Your printer manual will tell you what kind of printer you have. One end of the printer cable will be connected to the appropriate port on the real panel.
The other end of the cable has to be connected to the printer. The connector is tapered so that you can only connect the cable one way. Normally, you will find small wire clamps on either side of the port to hold the connector securely. With the cable connected, press the wire clamps into the notches. This is required to avoid any damage that could be caused because of power fluctuations.
A monitor has a light indicator to show whether it is on or off. The brightness and contrast control knobs are used to adjust the brightness and sharpness of the text or image on the screen, respectively similar to the controls present on a TV. Some monitor also have knobs to position the image at the centre of the screen, these are the vertical shift and horizontal shift knobs used to shift the image vertically and horizontally, respectively.
When you are satisfied that everything is working as it should, turn the power switch off to stop the test. Maintaining your Computer To keep your computer system working properly, it is necessary to protect the hardware from environmental hazards, unreliable power supply and natural calamities. Parking refers to positioning the disk head on an unused area to ensure that the head does not damage the disk. Computer fundamentals By Angeh Desmith N. Operating Systems.
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Most user related problems can be easily fixed or avoided with a little computer knowledge. Third in an ongoing series of lessons that reveals valuable tips to make learning computers quicker, easier, and more fun. This lesson Macintosh Basics - Leopard Filesharing v. Demonstrated in OS Windows Basics: Using Shortcuts v.
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