The Hard Disk Drive (HDD):   In your system it is the “Data centre” of the PC. It is here that all your programs and data stored between the occasions that you use the computer. Your hard disk is the most important of the various types of permanent storage used in PCs (the others being the floppy disk and CD-ROMs, tapes, removable drive, etc.) The hard disk differs from the other primarily in three ways: size (usually large), speed (usually faster)) and permanence (usually fixed in the PC and not removable)

            Hard disk drives are almost an amazing as microprocessors in terms the technology they use and how much progress they have made in terms the technology they used and how much progress they have made in terms of capacity, speed, and price in the last 20 Years. The First PC Hard disk of 10 MB and a cost of over Rs. 2,500 per MB. Modern hard disk have capacity approaching 1 TB and a cost of less than one rupee per MB! At the same time, the speed of the hard disk and its interface has increased dramatically as well.    

 

Monitor:

 It is also called as Video Display Unit. It accepts programming instructions a sometimes a monitor is also referred to as a video display terminal

Floppy Disk Drive : The invention of hard disk relegated floppy disks to the secondary roles of data transfer and software installation . The floppy disk still persists, mainly because of its universality: The 3.5 inch 1.44 MB floppy is present on virtually every PC made in the last 10 years, which makes it still a useful tool. The floppy disk’s current roles is in the following areas :

   Ø  Data Transfer

   Ø  Small File Storage and Backup

   Ø  Software Installation and Drivers Updates

CD Rom or DVD Rom: CDs and DVDs are a common thing now-a-days. You get movies in CD’s, games in DVDs and books in CDs. Many technical magazines and books now come with CD and DVD packaged in them. CDs have really revolutionized portable storage, not only in entertainment in them. But also in computer use.  

 Keyboard: This is attached to a micro computer or the terminal of a mini large computer. A keyboard is similar to the keyboard of a typewriter. It contains alphabets digits special characters and some control keys, When a key pressed, an electronic signals is produced which is detected by an electronic circuit called keyboard encoder. A Keyboard encoder may be special IC or single chip microcomputer used as encoder. The function of an encoder is to detect which key has been pressed and send a binary code.

Mouse : Mice (plural for ‘Mouse’) first broke onto the public stage with the introduction of the Apple Macintosh in 1984, and since then they have helped completely redefine the way we use computers1 Every day of your computing life, you reach out for your mouse whenever you want to move your cursor or activate something. Your mouse senses your motion and your clicks and sends them to the computer so that it can respond appropriately.

COMPUTER HARDWARE BASICS

Day 1.  

Personal computer (PC): When we say “PC” we refer to those personal computers that have Intel x86 (central processing unit) and run on Microsoft windows operating systems. There are other PCs like Apple’s Macintosh. But, we are not talking about them. The PCs that we talk about are those that belong to the family of PCs made by IBM (International Business Management Machines), the biggest and oldest computer.

 PC: The IBM PC released in 1981, It had Intel 8088 chip as its CPU Microsoft’s PCDOS as its operating system. Though Intel’s 16-bit 8086 were available, IBM selected the less powerful 8088 Microprocessor to reduce the cost of the PC. The operating system PCDOS became very successful though it did not have like sub-directories and hard disk support. It had 4” tall floppy disk drivers that ran 8” diskettes, a had 256KB RAM and had space a maximum of only five add on cards.

 

PC-XT: IBM introduced its next model called PC-XT (“XT for extended Technology).This PC a few additional features over the original PC and hence the ‘XT’. The PC-XT had built-in 10 MB hard disk and had 8 bit input and output slots, greater power supply capacity and completely socketed memory. This Pc completely different mother board circuit to support hard disk and ram expansions up to 640kb. The reset button was introducing this model.      

PC-AT: In 1984, IBM introduced the AT (short for Advanced Technology) which was five times faster than XT. This computer’s Intel 80286 CPU set the standard for the all other PC type computers. Intel’s 286(‘80’ is dropped) chip is a 16 bit processor. It supported 16 bit bus transfer and 24 bit memory addressing. By a memory management feature called “Protected Mode”, the processor supports to allowed access of up to 16 MB and could support muti- tasking operating system like UNIX. It also support to three more DMA(Direct Memory Access). After The 8086 chip, Intel produced chips by the names 80186, 80286, 80386 and 80486. Each chip had new features old chips. 

Pentium: Pentium was introduced in 1993. Pentium as 64 input output pins but internally processes 32 bit at a time. In addition to all the instructions of previous x86 processors it has few new ones also. It has 16KB level-one built-in cache memory which double 486 processor.

Pentium with MMX was the next chip introduced by the intel. Its instruction set has additionally a new class of instructions called “Multi media eXtensions”(MMX).These are 57 new integer instructions and several data types. These will be helpful in multi-media applications that include visual complex graphics tasks as well as full – motion video and high-quality sound.

Pentium II  : In the middle of 1996, Intel brought out Pentium II. Effectively, it is slightly improved Pentium pro Plus MMX technology. But the level-two cache is on separate chip and expanded to 32 KB. Processor speed is 533, 500, 466 MHz.

Pentium III :   This processor release by Intel in 1999. This processor is faster 450MHz and as new instructions. These instructions make it possible to run 3D graphics imaging, stream video, speech recognition and audio applications quickly. PIII processors are now available with clock speeds to Up to 1.0 GHz. 

Pentium VI : Intel corporation announced on June 28, 2000 the Intel ® Pentium ® 4 proccessor brand for its new generation of desktop micro processors. Scheduled to be introduced in the second half of 2000, The new Pentium 4 processor is based on  revolutionary technology designed to maximize performance today and in the future, keeping consumers on the cutting edge of the Internet.   

A SYSTEM CONTAINS FOLLOWING PERIPHERALS:

Ø  Main Board (Mother Board)

Ø  Processor

Ø  Ram (Random Access Memory

Ø  SMPS (System Main Power Supply)

Ø  Cabinet (System Case)

Ø  HDD (Hard Disk Drive)

Ø  Monitor

Ø  Floppy Disk Drive

Ø  CD Rom or DVD Rom

Ø  Keyboard

Ø  Mouse

Mother Board : The mother board is the most important component in a PC system. The main purpose of the mother board is to interconnect the several functional parts of the PC. There are several on the board for this purpose. For example, to connect a floppy drive to your PC you have plug in IDE(Integrated Device Electronics) card on the slot meant for this. Add on cards like this IDE Card are called daughter boards (non son-boards)

There are different types of interface cards that can be attached to a PC. These interface cards are inserted into one of input output expansion slots available in the mother board in old mother boards. 

The following are the most common interface cards are used in PCs. In old model mother boards

 

-          Video Display Card : Used to connect Monitor

-          IDE cards : To connect Floppy Disk, Hard disk, CD or DVD Rom Drives

-          Network Interface Card : Used to attach PC to a Local Area Network

Processor: Different Processors are we discussed in the following units. All data lines and address lines are made available for internal operations and are also available on the edge connectors for interfacing Ex : Pentium I, II, III, IV, Pentium Core 2 Duo , I3 Processor, Etc., 

 

RAM: The programs and data are stored in RAM on the mother board for immediate used by the Processor. The Processor accesses the memory for data and program random manner. This method of access is Random Access. Each location of memory has unique address. A single line can address two memory locations of each one byte. 8088 Processor with 20 address lines can be addressing 1 MB Memory. But the first 640 KB of the 1 MB memory is addressed as RAM and remaining addressable memory is used other functions. Most memory chips are packaged into small plastic or ceramic packages called dual inline packages or DIPs. A DIP is a rectangular with rows of pins running along its two longer edges. These are the small black boxes you on SIMMs (Single Inline Memory Module). DIMMs( Dual Line memory Module ) or other larger packaging styles. The DIP has been the standard of packaging integrated circuits since invention of the CPU   

 

SMPS: System Main Power Supply, inside the system unit you will big gray box with lots of wires running out of it and connecting it to basically everything. following figure

 

This gray box is the Power supply. The power supply converts an ordinary household current into lower voltage direct current for the parts of the PC.

The power supply has three jobs to do :

1.      Covert wall outlet A/C electrical power into suitable D/C voltages

2.      Monitor those D/C voltages

3.      Remove the heat that results from consumption of the electrical power.

SMPS voltage levels and functions as follows

S.No	Power	Functions
1	+ 5v	Powers the operational circuits on the mother board
2	+ 12v	Power the disk drives (floppy drive, hard disk drive and CDROM drive) and the system’s dynamic memory
3	- 5v	It is used for memory bias voltage and analog circuits in the disk adaptor
4	-12 v	The positive and negative 12v dc points powers the serial interface card

The power supply also incorporates a switching regulator to hold the output voltages very close to tolerances. Hence this unit is called Switched Mode Power Supply.

SREE NAYAN TECHNOLOGIES - COMPUTER ONLINE TRAINING : A computer is a machine that can be instructed to ...

SREE NAYAN TECHNOLOGIES - COMPUTER ONLINE TRAINING : A computer is a machine that can be instructed to ...: A computer is a machine that can be instructed to carry out sequences of arithmetic or logical operations automatically via computer prog...

Classification of Computers:

This classification of computer system is based upon the size of the memory, the speed and operating features of the computer systems. A variety of computer systems are now available in the market.

1.   Micro computer : It consist of a microprocessor chip as CPU (central processing unit), semiconductor ROM(Read only Memory) for storing only Essential programs for operating systems, RAM (Random Access Memory) for data storage mad input output devices like keyboard, printer etc. They have limited input and output capabilities, little software and little storage capacity as compared to the other types. Typical micro computers have a memory capacity of 64KB or 256 or 1 MB or even more.

Micro computers are used extensively as personal computers (PC’s). These are designed for the use of professionals. They were used for wide range of applications and hence they are called General purpose Computers. Many micro computer languages are used of various purposes. BASIC, COBOL, FORTRAN, PASCAL are included in them, IBMPC, APPLE I and III are the examples of typical micro computers.

2.    Mini Computers: These are faster than micro computers, the speed of CPU around the one million instructions per second. Digital Equipment Corporation (PDP-8 and PDP -11) is the largest manufacture of mini computers. HCL – HORIZAN, SN 23 are also manufactures of such computers. Fast line printers, large disk capacity disks, magnetic tapes are peripheral device used with mini computers.

3.   Main Frame Computers: These computers are manufactured in different models, capacities and prices they are faster than the mini computers. They are also called midi computers. The CPU speeds are range 1 to 10 million instructions per second and even more in many cases.  

4.  Super Computers: Super computers are also called Maxi – computers. They are high speed computers. The speed of such computers is more than 100 million instructions per second. Wide ranges of memory capacity models of this type or available. Various types of peripherals are connected to super computer systems. High speed disks printers 100 MB, high speed tapes are the examples of it.

Generation of computers:

                 The generation of computers is basically differentiated by a fundamental hardware technology. Each new generation of computer is characterized by greater speed, large memory capacity and smaller size than the previous generation.

  Ø  First Generation:  The computer produced and used between 1940-1955 was called first generation. In this generation computer were characterized by vacuum tubes (valve) circuitry. Hence they were very large, they were placed in large air-conditioned rooms had small internal storage and were relatively very slow. The first generation machines used punched paper tape, punched card, magnetic wire, magnetic tape and printers as input/output devices. The trends, which were encountered during the era of first generation computers were:

-          The first generation computer control was centralized in a single CPU, and all the operations required a direct intervention of the CPU.

-          Punched cards were used as input device.

-          Magnetic tapes and magnetic drums were used as secondary memory.

-          Binary code or machine language was used as secondary memory

  Ø  Second Generation Computers:   The computer produced after 1955 are called second generation of computers. They had faster access and were more reliable than first generation of computers. In this generation Transistors replaced vacuum tubes of first generation period. By this time a wider range input/output devices such as higher performance magnetic tapes, magnetic drums and early magnetic disks were available. During the second generation, computer languages such as FORTRAN and ALGOL were introduced. The second generation of computers started with the advent of transistorized computers

  Ø  Third Generation Computers: IBM announced the third generation of computers in 1964 with its 360 line of computers. They were used integrated circuits(IC) in the hardware. It also had the provision of facilities for time- sharing and multi programming. The speed and storage capacity of their computers were much higher than the previous generation computers and the size was much reduced. This computers are low cost , size smaller , reduce in power and cooling requirements.

  Ø  Fourth Generation: The fourth generation computers were produced after 1970. The term fourth generation computer is used to designate micro computers which use large-scale integrated circuits (LSI) and very large integrated, had greater input/output capacity and system reliability. The most important criterion that can be used to separate them from third generation computers is that they have been designed work efficiently with the current generation of high level languages.

  Ø  Fifth Generation:  In October 1981, a conference of 300 computer scientists and engineers from fourteen countries was held in Japan to discuss the features of the fifth generation computers. This machine will incorporate artificial intelligence, which will not be far different from that of human intelligence. They will use stored reservoirs of knowledge to make expert judgment and decisions. They will process non-numerical information such as pictures and graphs.  

Components of Computers:

Computer is an electronic Data processing machine. It made up of various devices, which help you to interact. Process it and output is the result, a computer system has three essential parts

INPUT (To give instructions to system from user)

CENTRAL PROCCESSING UNIT (CPU)

OUT PUT (To give output from system to user)

Block Diagram of a Computer:

 The computer consists of three parts: Input Device, CPU and output device.

 

  

Input Device: This device is used to give instructions from the user to system using Input Device. Ex: Keyboard, Mouse, Scanner, Etc., 

Keyboard: This is attached to a micro computer or the terminal of a mini large computer. A keyboard is similar to the keyboard of a typewriter. It contains alphabets digits special characters and some control keys, When a key pressed, an electronic signals is produced which is detected by an electronic circuit called keyboard encoder. A Keyboard encoder may be special IC or single chip microcomputer used as encoder. The function of an encoder is to detect which key has been pressed and send a binary code.

Central Processing Unit:

 This is also called system Unit, which is a technically known as Microprocessor CPU is the brain of computer. It is made of three units:

  Ø  Control Unit:  The control section of the CPU maintains and directs the operations of the entire system. It acts the central nervous system for all components through it does not process any data.

  Ø  Arithmetic and Logical Unit (ALU): ALU processes the data entered. All types of processing, Mathematical calculations, comparison decision making and processing of non numeric information take place in ALU and data is once again moved RAM

  Ø  Memory Unit:  Memory refers to the storage space in computer. Memory stores the data entered as well as the result given by the computer. Memory works on the application of binary system. The basic unit of memory is byte. Memory units can be divided into two sub parts :
    (a) Primary storage        (b) Secondary Storage

Output Device: This device is used to give Output from system to user using output Device. Ex:  Monitor, Printer, Etc., 

Monitor: It is also called as Video Display Unit. It accepts programming instructions a sometimes a monitor is also referred to as a video display terminal.

Characteristics of Computers

The increasing popularity of computers has proved that it is very powerful and useful tool. The power and usefulness of this popular tool are mainly due to its following Characteristics:

  Ø Automatic: A machine is said to be automatic, if it works by itself without human intervention. Computers are automatic machines because once started on a job, they carry on, until the job is finished, normally without human assistance. However, computers being machines cannot start themselves. They cannot go out and find their own problems and solutions. They have instructed. That is, a computer works from a program of coded instructions, which specify exactly how a particular job is to be done. Some of the other characteristics of computers, such as speed and accuracy, are due to the fact that they are automatic, and work on a problem without any human intervention.

  Ø  Speed: A computer is a very fast device. It can perform in a few seconds, the amount of work that human being can do in a entire year – if he worked day and night and did nothing else. To put it in a different manner, a compute does in one minute what would take a man his entire lifetime.

  Ø  Accuracy:  In addition to being very fast, computers are very accurate. The accuracy of computer is consistently high, and the degree of accuracy of particular computer depends upon its design, however, for particular computer, every calculation is performed with the same accuracy.

Errors can occur in a computer. However, these are mainly due to human rather than technological weakness. For example, errors may occur due to imprecise thinking by the programmer (a person who writes instructions for a computer solve a particular problem) or incorrect input data. Computer errors caused due to incorrect input data or unreliable programs are often referred to as garbage-in-garbage-out (GIGO)

  Ø  Versatility: It is one of the most wonderful things about the computer. One moment, it is preparing the results of an examination, the next moment, it is busy preparing electricity bills, and in between, it may help and office secretary to trace an important letter in seconds. All that is required to change its talent is to slip in a new program ( a sequence of instructions for the computer into it. Briefly, a computer is capable of performing almost any task can be reduced to a series of logical steps.

  Ø  Storage: This is very important character of the computer, which separates it from other machine. The basic unit of storage is bit (Binary Digit). The speed with which computer can perform, i.e. to input data and the instructions for processing, is humanly impossible. The storage space available in the central processing unit, being limited, large quantity of data and entire introductions of all the required programs cannot be stored in it. These are stored outside and read into the memory of CPU at the time of processing.

Bit                            – Smallest unit of storage
Byte                        – 8 Bits

Kilo Byte              – 1024 Byte

Mega Byte          – 1020 Kilo Byte

                             Gaga Byte           – 1024 Mega Byte
                              Tara Byte             – 1024 Gaga Byte