Hardware

HARDWARE AGB111 2013-14

HARDWARE • The major physical components of a computer system are input devices, processing devices and output devices.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Main hardware components 1. Main memory 2. Central Processing Unit (CPU) a. Arithmetic Logic Unit (ALU) b. Control unit 3. Secondary memory 4. Input devices 5. Output devices 06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Input devices Input devices are the machines designed for data entry purposes and for human-machine communication. Examples for input devices are keyboard, mouse, input pen, microphone, etc

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Key Board • Provides the user a means to input data to the computer • There are three sets of key Pads 1.Numerical Key Pad 2.Alpha-numerical Keys 3.Functional keys

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Track ball

Light pen

It looks like a mouse, but it lies on its back useful where there may not be any flat surface available while travelling in a car or in a plane

06-11-2013

Pen like device with a light on one end and a wire connected to the computer on the other end. One can touch the screen with the pen and the system recognises the light pen's location. Thus the pen can be used for drawing on the screen.

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Other input devices

• Joysticks, Tablet, Scanner, Voice recognition software, etc.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Concept of computer storage Von Neumann (1947) • First electronic computer using stored programme called EDSAC (Electronic Delay Storage Automatic Calculator) was announced in 1949.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Central Processing Unit • It is the brain of the computer where all the processing takes place.

• Temporary memory Unit • Permanent memory Unit • Arithmetic and Logical Unit

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Central Processing Unit • Power supply • Mother Board- Microprocessor Memory- RAM Driver Controller • Hard Disk drive • User- CD- ROM drive –Floppy drive

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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CPU

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Temporary memory Unit(RAM) • Also called Internal memory • Generally called as Random Access memory (RAM)- Can store data as long as the power is on, once the power goes off all the data in RAM disappears) • Also called Semi conductor memory- (any part of the memory can be accessed directly (randomly) for reading/writing information.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Read only memory (ROM) • Information is built onto the ROM chip during manufacturing. It can’t be altered and fresh information cannot be written into ROM. • This memory can be transferred to other memory like RAM etc, ROM can be classified into 1.

PROM - Programmable ROM. This is used to store programs. Once programmed, PROM is essentially ROM. 2.

EPROM - Erasable PROM. This is used to store programmes, erase them subsequently and reprogram.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Permanent memory Unit • Data can be stored permanently.

• Memory is measured in terms of Bytes.

One Byte = 8 bits ( It is a binary digit which has either 0 or 1 as its component 8 bits- 1 byte 1024 bytes -1 KB(Kilo Byte) 1024 KB – 1 MB(Mega Byte)

RAM will use 8, 16,32,64,128, 256 bits etc.

1024 MB – 1GB(Giga Byte) 06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Arithmetic Logic Unit (ALU) ALU -for all the arithmetical and logical operations like manipulations of numerical data, comparison of relative magnitudes of numericals.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Main memory The primary storage (also called as main memory) is used for the following four purposes: • To have input storage area for storing data until processing.

• To provide working storage space for storing data being processed and intermediate results.

• To provide output storage area for holding finished results.

• To have program storage area for holding processing instructions.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Control section Maintains order and directs the operation of the entire system by selecting, interpreting and seeing to the executions of program instructions. it acts as a central nervous system for the data manipulating

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Special storage areas in the CPURegisters A register is characterized by its size, i.e. the number of bits it can hold.

• Instruction register - This register holds the instruction being executed currently.

• Programme counter - This points to the next instruction to be executed.

• Accumulator - This holds the accumulated results of computation.

• Working register - This holds the intermediate results of computation.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Speed of a CPU • Usually measured in cycle time, i.e. the time required to execute one basic instruction, which is measured in MIPS. (million instructions per second) •Processing speed is the data path width, which provides the communication link between a memory location and the CPU. -A 16-bit data path brings twice the amount of information at a time into the CPU as compared to an 8-bit data path 06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Speed of a CPU(Contd.) • Word size of a processor is a measure of the amount of information that can be processed simultaneously by the CPU, which is the same as the size of a register.

Cycle time, data path width and word size jointly determine the processing power of CPU expressed in MIPS (million instructions per second).

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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CPU's processing power- Is measured in million instructions per second (MIPS).

• One 1000th of a second on first generation computers, • Micro seconds (one millionth of a second) on second generation computers, • Nano seconds (one billionth of a second) on Third nd fourth generation computers • It is expected to be measured in pico seconds (one 1000th of a nano second) in the fifth generation computers.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Cache • It is used by CPU of a computer to reduce the average time to access the memory.

• The cache is a smaller , faster memory which stores copies of the data from the most frequently used main memory locations.

• It enables CPU to access recently used information very quickly.- 256 Kb, 512 kb, 1MB cache( larger the cache, the better with the system power0.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Hard Disk • It is part of CPU • It is permanent storage device.

• Present day computers have hard disk with memory capacity of 40/80/160 GB.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Memory units are interfaced with CPU through memory controllers Two high-speed storage areas Memory Buffer Register (MBR)- store a word in the main memory, the CPU puts the word into the MBR Memory Address Register (MAR) - its location address in the MAR and sends a write signal to the memory This leads to the process of writing the word available in MBR in the specified memory location erasing its previous contents, if any.

Similarly, to fetch a word from the main memory, the CPU puts the location address of the word in the MAR and sends a read signal. Then the requested word is made available to the CPU in the MBR. 06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Secondary storage devices For permanent storage of data, external storage media can be used with a PC Secondary memory provides economical storage of large volumes of data on magnetic media, thereby offering permanent (non-volatile storage).

There are 2 types of secondary memory viz 1.Serial access memory, which allows only a serial access of data 2.Random access memory, which allows random access of data. E.g. for serial access memory is magnetic tape. Example for RAM are magnetic disk, floppy disks etc.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Disk drives - device specially designed to perform the functions of writing on or reading from external storage media is called the disk drive • •

The disk drive is contained within the system unit.

Floppy disk drive Hard disk drive CD drive.

Storage media (floppy disk and the hard disk on which data is stored are the storage media) • Storage devices (Disk drives does the storage on the media) External storage media commonly used.

1. Floppy disk, 4. Cartridge tape 2. Hard disk 5. Pen drive 3. Compact disc.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Output devices

Monitor • Monitors provide a visual display of data.

Special circuit called the adapter card determines the capabilities of a monitor. Some popular adapter cards are • Coloured Graphics Adopter (CGA) • Extended Graphics Adopter (EGA) • Vector Graphics Adopter (VGA) • Super Vector Graphics Adopter (SVGA)

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Resolution of the monitor • The smallest dot that can be displayed is called a pixel. The number of pixels that can be displayed vertically and horizontally gives the maximum resolution of the monitor. • The resolution of the monitor determines the quality of the display. The higher the resolution the better is the quality of the display. Some popular resolutions are, 1. 800 x 640 pixels 2. 1024 x 768 pixels 3. 1280 x 1024 pixels 06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Serial Printer “Dot Matrix Printer (DMP).

Here, a character to be printed is made up of a finite number of dots.

Many dot matrix printers are bi-directional, i.e., they print left to right as well as form right to left on return. This enhances the speed of printing. The printing speed is around 300 characters / sec.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Letter quality Printer

• “Inkjet Printer” (non – impact printer). A high resolution inkjet printer has around 50 nozzles with in the height of 7 mm and can print with a resolution of 300 dots / inch. Currently, colour inkjets are also available in the market.

The printing speed is around 120 characters / sec.

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Laser Printer An electronically controlled laser beam traces out the desired character to be printed on a photoconductive drum.

• Low speed laser printers, which can print 4 –16 pages / min are now very popular.

• Very fast printers print 10,000 lines / min and it is very costly.

• Colour laser printers • Apart from printers the other output devices are • Drum plotter • Flat bed plotter • Micro film and micro pitch • Graphic display device • Speech output unit 06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Differences Hard Disk Primary storage device Inside the CPU Fixed size

Hard ware Physical equipment

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Floppy Disk Secondary storage device Outside Variable size

Soft ware Set of programme

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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Thank You

06-11-2013

Dr R Jayashree, Asst Prof Veterinary College, Bangalore

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