COMPUTER FUNDAMENTALS

INFORMATION consists of facts and items of knowledge. It can be anything that has meaning to people. Usually information is expressed in words and numbers. However, it can be expressed in other forms, such as sounds, measurements or pictures.

Ex: A list of names and addresses. The contents of a letter. The words of a song. A map.

DATA Is information in which it can be processed.

Ex: A word processed letter stored on a floppy disc A song written as sheet music so that it can be played. A telephone conversation converted to electrical signals to be sent down the

wires.

PROCESSING INFORMATION

Information processing is the organization, manipulation and distribution of information. Sorting a list of names and address into alphabetical order. Producing a letter with a word processor, saving it on floppy disc and then sending

it by electronic mail. Transmitting a conversation over the phone system.

PROCESSING OF INFORMATION WITHOUT MACHINES

Ex: Listening to songs and deciding which ones are best. Reading a map to get from one place to another.

THE DATA PROCESSING CYCLE

When data is collected and processed, whether by computer or by other means, a set of operations is carried out on it. The sequence of operations : data collection, input, process, output is called a data processing cycle.

INFORMATION TECHNOLOGY

INFORMATION TECHNOLOGY (IT) is all types of equipment and programs which are used in the processing of information.

ex: A computer. A calculator. A fax machine. A telephone.

USES OF INFORMATION TECHNOLOGY

The term ‘information technology is also used to refer to the uses of this technology. The main types of use involved are:

Presentation of information. Handling information. Searching data, sorting it into order and analyzing Producing modules of real situations Data communication. Control and measurement

DIGITAL AND ANALOGUE DATA A device is digital if some quantity in it can be set to a number of different

separate values or states. Data is then represented by combinations by these values. Usually the devices are binary and data is represented as a succession of 1s and 0s.

An analogue device is one in which data is represented by some quantity which is continuously variable. The value of a data item at a given time is represented by the size of the quantity measured on a fixed scale.

COMPUTERS

A Computer is a programmable, multipurpose machine that accepts data (e.g. raw data, facts & figures) and processes, or manipulates it into information we can use, such as summaries or totals

EX: An Automated Teller Machine (ATM) computes the deposits and withdrawals to give you the total in your account.

Computer: (ISO) A programmable functional unit that consists of one or more associated processing units and peripheral equipment, that is controlled by internally stored programs and that can perform substantial computation, including numerous arithmetic operations or logic operations, without human intervention during a run.

A computer may be a stand-alone unit or may consist of several interconnected units.

HISTORY OF COMPUTERS

3000 BC the ABACUS a rudimentary first computing device developed

1642 – Blaise Pascal built the first mechanical digital calculator Pascaline.

1822 – Charles Babbage invented Difference Engine with a mechanical memory to store results.

1840 – Ada, the first programmer suggested binary Data storage rather than decimal.

1880 – Dr.Herman Hollerith developed the punched card that would contain data coded in form of punched holes.

1939 – Dr. John Vincent Atanasoft produced the first prototype electronic computer.

1944 – Aitken built Mark 1 the first automatic, sequence controlled calculator; used by military to compute ballistic data.

1947 – Mauchy and Eckert built ENIAC – 2nd Electronic digital computer.

1949 – Maurice, Eckert and Von Neumann built EDVAC the -1st stored program computer.

1950 – Turing built Ace – 1st programmable computer.

1951 – Mauchy and Eckert built UNIVAC 1 – 1st commercially sold.

1960 – Gene Amdahl designed IBM System/360 mainframe computer – 1st general purpose digital using Integrated circuits.

1963 – Olsen with Digital Equipment Corporation produced PDP-1 – 1st Mini computer.

Ted Hoff of Intel Corporation produced microprocessor Intel 4004.

1975 – H.Edward Roberts – 1st Microcomputer.

1976 – Seymour Cray CRAY-1 Supercomputer.

1977 – Stephen Wonzniak and Steven Jobs built first Apple Microcomputer.

1980 – Lower cost Personal Computers.

COMPUTER ORGANIZATION AND ARCHITECTURE

ALU

Internal Communic

ation

Registers

Control Unit

CPU Storage/Input Internal Memory

RAM (Read/Write) ROM (Read Only)

BUS SYSTEM

Input Interface Output Interface

Input DevicesKeyboardMouse/JoystickLight penScannerInfra-red rayVideo CameraMicrophone etc.

Output DevicesVDU(Monitor)PrinterSpeaker etc.

External Storage : Hard Disk, Floppy Disk, CDROM, Magnetic Tape

Block Diagram of a Modern PCBlock Diagram of a Modern PC

Output

ALUControl

Main Memor

y

Processor

ALU

Internal Communic

ation

Registers

Control Unit

CPU Storage/Input Internal Memory

RAM (Read/Write) ROM (Read Only)

BUS SYSTEM

Input Interface Output Interface

Input DevicesKeyboardMouse/JoystickLight penScannerInfra-red rayVideo CameraMicrophone etc.

Output DevicesVDU(Monitor)PrinterSpeaker etc.

External Storage : Hard Disk, Floppy Disk, CDROM, Magnetic Tape

Block Diagram of a Modern PCBlock Diagram of a Modern PC

THE CENTRAL PROCESSING UNIT

Processor:- The heart of any computer system. It consists of ALU, control elements and small memory units called registers.

ALU:- All calculations and all comparisons take place in this unit.

Control Unit:- This interprets any instruction it receives from memory and directs the sequence of events Necessary to execute the instruction. CU uses a system clock which synchronizes all tasks by sending out electrical pulses.

INPUT DEVICESInput devices are used to feed data and instructions to the computer system.Input devices provide the interface between the outside world and the computer system for this purpose. An input device is a peripheral which accepts data and sends it to the central processing unit.Ex. of input devices

The keyboard Alight pen An Electronic digital weighing scale interface d to a computer A document reader A mouse.

INPUT FROM KEY BOARD

The usual keys supplied are The alphabet The digits 0-9 Other text characters Cursor and other control characters Keys which change the function of other keys Function keys.

DOCUMENT READERS

OMR, OCR and MICRA document reader is a device which read data straight from a form.Ex;

Optical Mark Recognition(OMR) Optical Character Recognition(OCR) Magnetic Ink Character Recognition(MICR)

OPTICAL MARK RECOGNITION. (OMR)

OMR is a system of reading lines or marks which have been made in exactly the right positions on a card or document.

APPLICATIONS OF OMRThe documents to be read have empty boxes to take the marks. These have been preprinted on to the documents together with information telling the user what to do. The person preparing the data makes pencil or ink marks in the appropriate boxes.

The data to be input has to be simple because the user can only make marks and cannot write any information.

There has to be large number of documents to justify designing and printing them.Ex: marking multiple choice question papers.

OPTICAL CHARACTER RECOGNITION (OCR)

An optical character reader can recognize characters from their shape. As with OMR light is reflected from the paper and form the ink. In OCR however the reader has to workout what the characters are.Scanners were originally design to scan pictures but they can also be used to read text.

MOUSE

A mouse is an input device designed to fit snugly under a hand while it is moved about over a table. Moving the mouse produce s movements of a cursor or a pointer on the screen.The mouse is also provided with one, two or three buttons. These are pressed to produce action when the user has moved the cursor to the right place.

USES OF MOUSE: To select options from a menu or from a set of icons. To position the cursor when editing text or using a design packages. To select an object in a drawing or a piece of text to be copied, moved or deleted.

OUT PUT DEVICES

There are several ways to produce output: Text output. Graphics output. Sound output. Video output.

TEXT OUTPUT

Is simply alphanumeric characters that makeup our language. Text output appearance ranges from type writer to typeset quality.

GRAPHIC OUTPUT

Includes line drawings, maps, presentations business graphics.

SOUND OUTPUT

Ranges from the message beeps produced by the computer system to the human voice to music and other forms of sound.

VIDEO OUTPUT

Photographs (still images) or moving images such as television and video taped material

Again we have 2 principle kind of output are:

Hard copy. Soft copy.

PRINTER

A printer is read only device, driven directly by a computer and provide permanent visual records called hard copy. The basic criteria for evaluating printers include:

Quality of the printed output. Speed at which printed pages are produced. Sound level during printing. Cost of printing media. Conservation of paper.

BASIC CLARIFICATION OF PRINTERS

Character printers. - Prints one character at a time. Line printers – Prints one line at a time. Page printers – Prints one page at a time.

BASIC METHODS OF PRODUCING PRINTOUTS

IMPACT PRINTERS:Form characters or images by striking mechanism Such as print hammer or wheel against an inked ribbon leaving an image on paper.Ex Low speed impact printers (Daisy wheel print head, Dot matrix printer head)

NON-IMPACT PRINTERS

Form characters or images without making direct physical contact between printing mechanism and papers.Eg. Laser printer, Ink jet printer

DOT MATRIX PRINTER

This mechanism enable the print control up to the dot level on the paper, can be used to produce both text and graphics. Fast but noisy wear out ribbons very quickly.

LASER PRINTER

Excellent print quality and font selection. Fast printing and high quality graphics with color, high resolution Medium level noise but high cost. Primary disadvantages are expensive maintenance and the high cost of toner

cartridges.

INK-JET PRINTERS

Ink jet printers’ transfers characters and images to the paper by spraying a fine jet of ink.Offers nearly the quality of laser printing but not the speed. Low cost alternative for high quality printing.

MONITOR

Provide soft copy out put. Comes in either monochrome or color. A monochrome display a single color against a different color background Color display can show variety of colors.

Resolution- Describe the degree of details in a video display.

The higher the resolution the characters and images are sharper and crisper as fill image.

PLOTTERS

It is a specialized output device designed to produce high quality graphics in a variety of colors. Those are especially useful for creating maps and architectural drawings, although they may also produce less complicated charts and graphics.

TYPE OF PLOTTERS

Pen plotter Electrostatic plotter. Thermal plotter.

DATA STORAGE IN COMPUTERS

STORAGE OF DATA

The number of instructions and amount of data a computer can store in its memory is measured in bytes. A single character can be stored in one byte.

8 BITS = 1 BYTE( A BIT CAN BE EITHER 0 OR 1 )1024 B = 1 KILOBYTE 1024 KB = 1 MEGABYTE 1024 MB = 1 GIGABYTES

1024 GB = 1 TERABYTE

A BYTE is a small group of bits treated as a unit. It is usually the number of bits needed to store one character. Normally a byte consists of 8 bits.

WRITE – Data means to move it or copy from the main store to backing store.READ - Read data means to move it or copy from the backing store to main store.

STORES DIFFER IN: The speed with which they can be accessed. Whether they can store data when the computer is not running. Whether data on they can be changed.

Tow main categories of storage are Main store Backing store

MAIN MEMORY (MAIN STORE)There are two types of memory

ROM (Read-Only Memory) RAM (Random Access Memory)

Memory is the name given to a group of chips inside the processing unit. Here data is held temporarily whilst processing takes place.

CACHE MEMORY

Cache is an area of memory that holds frequently accessed data or program instructions for the purpose of speeding a computer system’s performance. .

READ ONLY MEMORY (ROM)

Is Memory which can be read from but not written to. ROM is permanent data and programs on it cannot be changed. It is not volatile. If ROM was volatile it would lose. Its data and it would not be possible to write it back. There are four types of ROM.

PROM: Programmable Read Only Memory EPROM Erasable Programmable Read Only Memory EEPROM: Electrically Erasable Programmable Read Only Memory

RANDOM ACCESS MEMORY (RAM)

Is memory which can be read from or written to. RAM is temporary. It contents can be changed. It is usually volatile.

The application of RAM 1. As the working store of the computer- as the temporary store for the program

which is running and data it is using.2. To store data being transferred to an from peripherals3. To store the contents of the screen

BACKING STORE

A STORAGE MEDIUM is the material on which the data is stored.Eg. Magnetic tape, Floppy disk, CD ROM

Storage DRIVE Is the piece of equipment which rotates the storage medium and access the data on it.

Characteristics of backing store1. Data is usually accessed using read/write heads. These transferred the data while

the medium rotates in the drive.2. Access to backing store is slower than to main store.3. They are not –volatile. the data is stored on the medium until it is deleted.

MAGNETIC DISCS

A typical Magnetic Disc has two surfaces or sides. Each surface holds data in circular tracks. Each track is divided into equal sections called sectors.

There are two types of Magnetic Disks Floppy Disc: Is a light flexible magnetic disc. Hard Disc: Is a rigid magnetic Disc

COMPACT DISC

All types of compact disc can be read by a computer if you have the right player interfaces and software.

A CD ROM is a compact disc normally of about 12cm in diameter. CD ROM’s of other sizes are also available. Ex. Electronic books which are 8 cm in diameter.

Data is written to the disc using a powerful laser beam to burn patterns in the surface. The discs are exchangeable and easy to transport.

Access to data is faster than floppy discs but slower than hard discs.

MULTI-MEDIA means presentation on a computer of information combining animated and still graphics, sound and text.

DATA FILES

Facts about FilesThe term File is used to describe any data or program stored on a backing store such as a disc or a tape.

A data file is an organized collection of data. It usually consists of a number of separate parts called records.

A Record is a subdivision of a file. It consists of a set of items of data which together can be treated as a unit.

Storage of FilesCreating a fileOrganizing data into a file means creating a file.

Saving a fileCopying all record from main store on to a backing store

Types of file

Data Communications

Data communication is the process of sending data electronically from one computer or similar device to another.

Linking one computer to another permits the power and resources of that computer to be tapped. It also makes possible the updating and sharing of data at different locations.

Computers that are located in the same room or office building can communicate data through a direct cable link.

Computers located far away use a special form of data communication – telecommunication or telegraph.

Local Area Network (LAN) - LANs are networks usually confined to a geographic area, such as a single building or a college campus. LANs can be small, linking as few as three computers, but often link hundreds of computers.

Metropolitan Area Network (MAN) - MAN is basically a bigger version of a LAN and normally uses similar technology. It might cover a group of near by corporate offices or a city and might be either private or public.

Wide Area Network (WAN) - Often a network is located in multiple physical places. Wide area networking combines multiple LANs that are geographically separate. This is accomplished by connecting the different LANs using services such as dedicated leased phone lines, dial-up phone lines (both synchronous and asynchronous), satellite links, and data packet carrier services.

LOCAL AREA NETWORK

Star Topology Ring Topology

WIDE AREA NETWORK