Hardware
A closer Look at the Hardware
closer Look at the Hardware
Keyboard:
The keyboard has already been identified as an input device. This is a component
that closely resembles a typewriter console.
While working on the PC using a keyboard, you eill notice a flashing point on
the VDU. This is the cursor. When you press a keyboard, a character is displayed
at the point where the cursor is flashing and the cursor moves one position
forward. The keyboard provides different keys to perform various operations.
(Refer below table)
| Key | Function |
| F1-F12 (Function Table) | Used to perform special functions that depend on the software that is being used |
| Caps lock | Use to execute an instruction or data being keyed in through the keyboard. |
| Shift | Caps
lock off: If pressed simultaneously with a character key, a capitalized
alphabet is input. Caps lock on: If reverses the above effect. Also used to input the upper, symbols of keys with two symbols or characters on them. |
| Ctrl, Alt | Pressed with other keys, they input special message to the computer. |
| Backspace | Used to erase the characters to the left of the cursor position. |
| Num-Lock | Used to activate the numeric keys on the numeric keypad. |
| Cursor Movement Keys | Used to move the cursor in direction indicated |
| Home, End, Page Up, Page Down | Used to perform special functions, with which you will become familiar during the course. |
| Insert | Used to insert characters at the current cursor position. |
| Delete | Used to delete characters at the current cursor position |
| Esc | Depends on application, usually used to cancel a command. |
| Print screen | Used to print whatever is displayed on the screen. |
Mouse:
A mouse is a small device that is connected to the system unit by means of a long wire. This is another input device, whose movement causes the corresponding movement of a pointer on the screen. It usually has two or three buttons. Using it, the user can select options from the screen.
Visual Display Unit (VDU)
Let us take a closer look at an output device. Data that has been processed needs to be displayed to the user. This is done using the monitor or the VDU. The VDU is similar to a TV screen and can display both text and graphic images. These displays can be either in black & white or color.
Printer:
The output on the VDU can't be stored for later reference. For a permanent output,
you would require a printer that is also a common output device Using the printer,
you can obtain the output on the paper. Printer are capable of printing at very
high speeds. The printers commonly used with the PC are the coot-matrix printer,
the ink-jet printer and the laser printer.
System Unit:
When data is input to a computer, it is processed and an output is produced at the output device. Processing takes place in the system unit. The component of the system unit that is involved in the actual processing is the microprocessor; another component of the system unit is the internal storage.
Internal Storage
Besides the microprocessor, the system unit also contains a storage area where
the data is stored before belong actually processed. This storage area is called
the internal storage. It is also referred to as primary storage, main memory
or Random Access memory (RAM). Internal storage capacities may differ in different
PC's. Typically, a PC will have an internal storage capacity of 640,000 characters
or more.
In computer technology, the storage capacity of a PC is measured in terms of
bytes. Where one byte can store one character. Character here refers to any
alphabet, number or other symbol. Therefore, to tore the ward Computer, 8 bytes
would be required, Just as there is a basic unit, gram, and another unit, kilogram
to measure weight, there is also byte and kilobyte (KB) to measure storage capacity.
One KB is approximately equal to 1000 bytes. Therefore, 1 KB can store approximately
1000 characters. Another common unit of measurement of storage capacity is the
megabyte (MB). which is equal to approximately 1000 KB. High Target capacities
are measured in terms of Gigabytes (GB). One GB is approximately equal to 1000
MB.
External Storage
Since the internal storage capacity of PC is limited, it places a restriction on how much data can be stored at a time for processing. However, this is not the only draw back, once the PC is switched off, or in case off a power failure, all the data stored in the internal storage is lost. This means that every time you want to work on the PC, you would have to input the data required for processing. External storage is also refereed to as secondary storage.
There are two kinds of external storage media used with a PC, they are:
Floppy Disk
Hard Disk
Another media for external storage is the cartridge tape, It is particularly
suitable for storage of large volume of data. Now CD-ROM and Magneto Optical
(MO_ disk have also became an important media to tore large volume of data.
Floppy Dist Hard Disk
Also refereed to as diskettes of floppies. Also referred to as the fix disk.
Removable. Suitable for data from one computer to another. Non-removable. It
is attached within the system unit.
Made of flexible tiny materiel. Less resistant to damage by heat, dust and accidental
twists. Less prone to damage since it is within that system unit and is packed
airtight.
The diskettes currently in use have a diameter of 3.5 inches with a storage
capacity of 730 KB or 1.44 MB. Can store data in the range of 20 Mg to 40 GB.
Diskettes having a diameter of 5.25 inches and typical storage capacity of 360
KB are also used, slowly being phased out
Comparison between a Diskette and a Hard Disk.
Disk
Drive
The disk drive is contained within the system unit. The drive for diskettes
is called Diskettes drive while the drive for a hard disk is called the Hard
disk drive.
It is important to differentiate between the storage media and storage devices. The diskette and the hard disk on which data is stored are the storage media, the disk drivers are the devices used for reading and writing. Going back to the analogy of the cassette tape recorder mentioned earlier. The cassette tape would be called storage medium while the cassette player is the storage device.
Software
A PC is incapable of performing any task with the hardware alone. It requires instructions that determine whether it will function as desired or not. Like data, instructions are also entered via the keyboard. In computer terminology, a set of instructions is called a program and one or more programs are called software.
Software
used on computers may be of different types. Some important classes of software
are:
Application Software
Compiler Software
The Operation Software
Application Software
We spoke of computer applications and identified certain areas where computers being used today. Software specially suited for specific applications is now available in the market, for example, software for billing systems, accounting software or software that enables the storage of documents. Such software is called application software since it is designed for a specific application.
Application software that takes care of variety of business and corporate needs can now be bought off the shelf. These are called standard software packages. They are reasonably priced and come on any standard PC.
Two popular standard software packages are Financial Accounting and Inventory control packages.
Though these packages are for very specific applications, there are general application software's like database management systems (DEMS). spreadsheets and word processors.
A spreadsheet package allows a user to enter number data, specify formula and perform calculations. Graphs can also be generated from the given data. A word processing package converts a PC into a sophisticated typewriting machine. It has the facility to perform spell checks, provide for synonyms, and allow changes or correcting in the document without having to re-type the entire document.
Compiler Software
Consider the case of four persons Rita, Bunu, Buddha Laxmi, Pramod, Amar, Anita who understand and speak English, Hindi, Nepali and Spanish respectively. To be able to understand each other, they would require some person or persons who could translate whatever is spoken into the language that each can understands.
Similarly, since there are so many programs written in different computer languages. The hardware also needs a translator to convert the computer language into a form that it can understand.
The computer only understands a language of electrical signals, called machine language. Software called the compiler converts the computer language into machine language. for example, there is a C complier that converts program written in the C language or machine language.
Operating system Software
Beside the application software and compiler software. There is a third kind of software, called the operating system, which is very important for the working of the PC.
When a user wants to store any data or program, it is stored at a location that is known only to the operating system. Therefore, the operating system performs the task of storage management. The operating system also performs device management. For instance, when a user wants to print information on the printer, or display information on the VDU, He or she does not have to bother about the actual transportation of the information from the internal storage to the VDU or to the printer. The operating system takes care of it.
All application software packages are written in computer language. There are various computer languages like C,C++, Fortran and Pascal, Each language is best suited for a particular application. C and C++ languages are used to develop highly complex software. Fortran is used for scientific application. Each language has its own vocabulary. There are some packages like Fox-Pro, Ms Access and Sybase that are more English like. Thus, even non-computer professionals, like executives and managers who have never studied computer science, cans learn to use these languages. So each language has its own vocabulary, each language differs form the other.
Memory
is the name of parts of computer that is use to store data. Programs and data
are stored in the memory unit of the CPU during processing. Memory consists
of storage locations. Memory is of two forms. Primary storage of main memory
is of two types.
Read only memory (ROM)
Random access memory (RAM)
There are certain essential functions that the computer must perform when it
is switched on.
ROM:-It
is permanently in built into the computer at the time of its production. ROM
is also called firmware. It stores a set of instruction and instructs the computer
how to work. The user cannot change these instructions. ROM is non-volatile,
that is, when computer goes off this instruction is not lost.
RAM:- It is short-term memory of volatile memory. That is, when the computer
is switched ON, the memory, which available to use, is RAM, but when the computer
is switched OFF, all the information disappears. RAM is temporary whereas ROM
is permanent memory.
So if we have some important pike of work that we would like to keep, we use secondary storage.
Secondary storage allows string large volumes of data. The contents of secondary storage are not lost when the power is turned OFF.
Secondary storage device are: -
Hard
Disk
Floppy Dis
Hard
Disks: -
Hard disk is a large capacity, permanent storage area that offers access to
the information stored on it. it is just like a long record and is made of smooth
metal or molar plastic, which is coated with magnetic material. Kate is stored
and retrieved in blocks. The tracks are therefore divided into block size regions
called sectors. Typically, 512 bytes per sector are stored. Control data is
recorded on the disk to indicate the start and end points of.
Sector. Hard disk is always fixed in the computer and cannot be removed. Huge number of data can be stored in this type of storage media.
Floppy
Disk:
Floppy disks are magnetically coated disks on which information; both programs
and data typed form the keyboard, can be stored and retrieved. Floppy disks
are put into and taken out of a disk drive. These are made of Mylar plastic
combed which magnetic oxide and are 5.25 and 3.5 inched in diameter.
CD-ROM
(Compact disk Read Only Memory)
It is non - erasable disk used for storing computer data.
Internal
Computer System
Computer is a group of integrated parts that have the purpose of performing
the operations called the program, which being executed qualifies it to be called
a system.
Computer system is basically made of input unit, by which data can be give to the computer, Central processing Unit, which does all arithmetic and logic operations, and Out put Unit which displays the result of these processing.
The data and instructions are understood by the main memory of computer where its Central processing Unit (CPU) takes place.
The processing result are displayed on the screen (Monitor) or printed by a printer.
The
output devices are Monitor or Printer.
The computer set of parts is called computer system.
Thus, in a computer system, perfect communication exits.
The main machine consists of primary unit (also called main memory) holds data
instructions and result of processing.
The Arithmetic logic unit (ALU) is used to perform a calculation and make comparisons.
(Decision).
The control unit (CU) co-ordinates flow of data among the various components.
The ALU and CU are together called the central processing unit or (CPU). the CPU is the main and heart combined which the central nervous system of computer.
Impute Device: Input devices are main types but basically they are meant for
presenting the information to the computer in a form understandable to its machine.
Output device: The results of any computer processing have to be communicated
to the user. Output devices translate the computer output into a form understandable
to the human beings.
Control Unit
The control unit directs all operations inside the computer. It is known as nerve center of the computer because it controls and co-ordinates all hardware operations.
Functions: It is used to transfer data from the input device to the memory output through ALU and also transfer the results from ALU to the memory and into the output device for printing.
Arithmetic Logic Unit: ALU operates on the data available in the main memory and amends them back after processing once again to the main memory.
Functions: It carries out arithmetic operations like addition, subtraction, multiplication and division.
Control Unit
Input
Arithmetic Logic Output
Device Unit Device
Main Memory
(RAM & ROM)
(Primary Storage)
Hard Disk
Floppy Disk
(Secondary Storage)
Control Processing Unit
It is the brain of the computer, which does the actual work of processing. Every input given to the computer needs to be processed before the actual output. The central processing Unit and its components. The CPU is an important part also called as the heart of the computer, having many more sub-components that are essential and perform discrete functions. Some of the main components in the CPU are discussed below.
1] SWITCH MODE POWER SUPPLY
All computer components require power supply, which the system draws from the AC mains. The internal power supply does the work of converting the AC input 230 volts into DC output of 5 and 12 volts. The internal power supply us normally as AMPS which provides the cable connections through which power is supplied as per the required voltage to the various, other units like the drivers, the mother board, the keyboard etc.
Whenever the CPU is switched ON/OFF, it is the SMPS, which is, switched ON/OFF, as the external switch is a part of the SMPS.
2] EXHAUST FAN
Whenever the computer is switched on, a fan that is part of the SMPS also starts functioning to give a cooling effect inside the SMPS unit.
3] SPEAKER
A small studio speaker is connected to the motherboard and is used to produce sound effect whenever required in various software programs.
4] MOTHERBOARD
One of the major components of the CPU is the Motherboard, which is large board containing a number of small chips and other additional electronic devices or components. The peripheral attachments are connected to the motherboard. The motherboard has important components like the Microprocessor, Clock, Memory RAM and ROM (Chips).
Microprocessor
The entire PC design is based on this chip. It can do all the mathematical calculations, comparisons logical operations and also attending to requests form attachments are connected like printers, restarting computer etc. The must widely used microprocessor used in computers is form Intel Company. They are usually available as 80286, 80386, 80486 and the Pentium chip.
Clock:
The time keeping is done by a clock, which provides signals by way of pulses to set up working pace. The speed of the clock is measured on the frequency of these pluses. The unit of measurement is in MHz or on the basic of the number of instructions per second. A quartz crystal is used giving accurate timings.
Memory:
The internal or Main Memory is in the form of chips. Here is the actual place
where the RAM and ROM are.
Bus: The Microprocessor works on the data stored in the RAM, Additionally the
instructions stored in ROM has to be brought into the RAM whenever required,
and therefore communication is essential between the microprocessor and the
memory chips as well as other found on the motherboard. This requires communication
or interaction is accomplished through a set of wires running between the various
components. These wires are called as Buses. There are various types of Bus
or wires depending upon the information they carry, the two main types are Data
Bus, a set of 8 wires approximately for carrying the address or location where
the data is to be stored in the memory.
Ports:
Input-Output devices like the printer, keyboard, Mouse etc are connected the CPU through sockets called as Ports. The Microprocessor communicates which the external world through the port. In other words they are the inlets and outlets of the microprocessor. The ports are basally of two types parallel and serial. A parallel port is capable of transmitting full byte. I.e. 8 bites are transferred simultaneously at a time, whereas, in case of a serial port eight bits Queue up and are then send through the cable.