Introduction to Computer

1. Introduction to Computer

2. Computers are everywhere! • Computers are showing up everywhere you look, and even in places you can't see. Computers check out your groceries, pump your gas, dispense money at the ATM, turn the heat on and off, control the way your car runs. They're everywhere!

3. What is a computer? A computer is an electronic device that executes the instructions in a program. Modern computers are electronic and digital. A computer has four functions: a. Accepts data Input b. Processes data Processing c. Produces output Output d. stores results Storage

4. All computer systems perform the following five basic operations:-  Inputting: The process of entering data and instructions into the computer system.  Storing: Saving data and instructions to make them readily available for additional processing, as when required.  Processing: Performing arithmetic operations (add, subtract, multiply, divide, etc), or logical operations on data, to convert them into useful information.  Outputting: The process of producing useful information or results for the user, such as a printed report or visual display  Controlling: Directing the manner and sequence in which all of the above operations are performed.

5. Block Diagram Of Computer

6. Input Unit : - It accepts or reads the instructions and data from the outside world - It converts these instructions and data in computer acceptable form. - It supplies the converted instructions and data to the computer system for further processing. Output Unit: - It accepts the results produced by the computer, which are in coded form, and hence, cannot be easily understood by us. - It converts these coded results to human acceptable (readable) form. - It supplies the converted results to the outside world. Memory Unit: - Memory unit are to store the data and instructions required for processing - They are to hold the final results of processing, before these results are released to an output device The Memory unit is comprised of the following 2 types of storage: Primary storage Secondary storage

7. Arithmetic Logic Unit: • The arithmetic logic unit (ALU) of a computer system is the place, where the actual execution of the instructions takes place, during the processing operation. • ALU’s are designed to perform the arithmetic operations (add, subtract, multiply & divide) and logical operations or comparisons. • Control Unit • The control unit acts as a central nervous system, for other components of the computer system. • It manages and coordinated the entire computer system • Central processing unit (CPU): • The control unit and ALU of a computer are jointly known as the Central Processing Unit • The CPU is the brain of a computer system & all calculations and comparisons are made inside the CPU. • CPU is responsible for activating and controlling the operations of other units of the computer system.

8. How CPUs work? A microprocessor -- also known as a CPU or central processing unit -- is a complete computation engine that is fabricated on a single chip.

9. Using its ALU (Arithmetic/Logic Unit), a microprocessor can perform mathematical operations like addition, subtraction, multiplication and division. • A microprocessor can move data from one memory location to another. • A microprocessor can make decisions and jump to a new set of instructions based on those decisions.

10. Some Terms Hardware: the physical parts of the computer. Software: the programs (instructions) that tell the computer what to do Data: individual facts like first name, price, quantity ordered Information: data which has been massaged into a useful form, like a complete mailing address Default: the original settings; what will happen if you don't change anything.

11. Input The input hardware allows you to enter data into the computer. The primary devices used are the keyboard and mouse. Keyboard – The keyboard looks like the typewriter. A numeric keypad is located to the right of the keyboard. Mouse – The mouse is a device that allows you to control the movement of the insertion point on the screen. There are other input devices, such as touch screen, joystick, modem, scanner, and voice recognition systems.

12. Touch Screen: A display screen that is sensitive to the touch of a finger or stylus. Touch screens are very resistant to harsh environments where keyboards might eventually fail. Joy Stick: A pointing device used to move an object on screen in any direction. Joy sticks are used extensively in video games and in some CAD systems Light Pen: A light-sensitive stylus wired to a video terminal used to draw pictures or select menu options. The user brings the pen to the desired point on screen and presses the pen button to make contact

13. Processing • The central processing unit or (CPU) is the "brain" of your computer. It contains the electronic circuits that cause the computer to follow instructions from ROM (read only memory) or from a program in RAM (random access memory). • CPU contains three parts. • Arithmetic Logic Unit – • ALU is where the "intelligence" of the computer is located. It can add and compare numbers. • Memory – • Memory contained on a chip are • Primary Memory

14. Primary Memory: It is also known as main memory, is used to hold pieces of program instructions and data. It is of 2 types:- • RAM (Random Access Memory) • ROM (Read Only Memory).

15. ROM memory has been installed on your computer by the manufacturer and can not be altered. • ROM determines all the basic functions of the operation of your machine, such as startup, shut down, and placing a character on the screen. • RAM is temporary memory, which displays the information you are working on. • RAM remembers what you see on your screen while you are working. • Today's applications required large amounts of temporary memory, which may require you to upgrade and add more RAM memory. 3. Control Unit – This is the part of the unit, which directs information to the proper places in your computer, such as calculation of information by the ALU unit or to store and print material.

16. PROM • Short for programmable read-only memory, a memorychip on which data can be written only once. Once a program has been written onto a PROM, it remains there forever. • Unlike RAM, PROMs retain their contents when the computer is turned off. • The difference between a PROM and a ROM (read-only memory) is that a PROM is manufactured as blank memory, whereas a ROM is programmed during the manufacturing process.

17. To write data onto a PROM chip, you need a special device called a PROM programmer or PROM burner. The process of programming a PROM is sometimes called burning the PROM. • An EPROM (erasable programmable read-only memory) is a special type of PROM that can be erased by exposing it to ultraviolet light. Once it is erased, it can be reprogrammed. An EEPROM is similar to a PROM, but requires only electricity to be erased.

18. What is an EEPROM? • Pronounced double-ee-prom or e-e-prom, short for electrically erasable programmable read-only memory. EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. • Like other types of PROM, EEPROM retains its contents even when the power is turned off. Also like other types of ROM, EEPROM is not as fast as RAM. EEPROM is similar to flash memory (sometimes called flash EEPROM). • The principal difference is that EEPROM requires data to be written or erased one byte at a time whereas flash memory allows data to be written or erased in blocks. This makes flash memory faster.

19. Cache Memory • Very fast memory used to improve the speed of a computer, doubling it in some cases • Acts as an intermediate store between the CPU and main memory • Stores the most frequently or recently used instructions and data for rapid retrieval • Generally between 1Kb and 512Kb • Much more expensive than normal RAM

20. Memory Cache speeds up a computer by storing data the computer has recently used. There are 2 types : Internal & External

21. External Cache If the computer cannot find what it needs in the Internal Cache, it looks in the external cache. This is usually located on the Motherboard. In some CPU chips the External cache is built in. Internal Cache When the computer needs data it first looks in the Internal cache. This is located on the CPU chip and provides the fastest way for the computer to get data.

22. Virtual memory Space on a hard disk used to temporarily store data and swap it in and out of RAM as needed.

23. Motherboard • This is the main circuit board that all of the other internal components connect to. • The CPU and memory are usually on the motherboard. Other systems may be found directly on the motherboard or connected to it through a secondary connection. • For example, a sound card can be built into the motherboard or connected through PCI (Peripheral Component Interface).

25. Output Output devices such as a monitor or printer make information you input available for you to view or use. Monitors: A monitor's front is called a screen with a cathode ray tube (CRT) attached to the screen. Portable computers use a (LCD) liquid crystal display. Today's super video graphics array (SVGA) monitors display 256 sharp and clear colors. Printers A device that prints text or illustrations on paper. There are two different types of printers. 1) Impact printer 2) Non Impact printer

26. Impact printers Include all printers that work by striking an ink ribbon. Dot-matrix are impact printers. Dot-matrix: Creates characters by striking pins against an ink ribbon. Each pin makes a dot, and combinations of dots form characters and illustrations.

27. Non-impact printers • Include laser printers and ink-jet printers. The important difference between impact and non-impact printers is that impact printers are much noisier. • Ink-jet: • Sprays ink at a sheet of paper. Ink-jet printers produce high-quality text and graphics. • Laser: • Uses the same technology as copy machines. Laser printers produce very high quality text and graphics.

28. Thermal printer: • Uses heat on chemically treated paper to form characters • An inexpensive printer that works by pushing heated pins against heat-sensitive paper. • Thermal printers are widely used in calculators and fax machines.

29. Plotter • A device that draws pictures on paper based on commands from a computer. • Plotters differ from printers in that they draw lines using a pen. As a result, they can produce continuous lines, whereas printers can only simulate lines by printing a closely spaced series of dots. • Plotters are considerably more expensive than printers. They are used in engineering applications where precision is mandatory.

30. Audio Output Devices • Windows machines need special audio card for audio output. • Macintosh has audio playback built in. • Audio output is useful for: • Music • CD player is a computer. • Most personal computers have CD players that can access both music CDs and CD-ROMs. • Multimedia

31. Integrated Drive Electronics (IDE) Controller This is the primary interface for the hard drive, CD-ROM and floppy disk drive. Peripheral Component Interconnect (PCI) Bus The most common way to connect additional components to the computer, PCI uses a series of slots on the motherboard that PCI cards plug into. SCSI Pronounced "scuzzy," the small computer system interface is a method of adding additional devices, such as hard drives or scanners, to the computer.

32. AGP Accelerated Graphics Port is a very high-speed connection used by the graphics card to interface with the computer. Sound card This is used by the computer to record and play audio by converting analog sound into digital information and back again. Graphics card – This translates image data from the computer into a format that can be displayed by the monitor.

33. Parallel Port Serial Ports USB Ports

34. SERIAL PORT • Considered to be one of the most basic external connections to a computer, the serial port has been an integral part of most computers for more than 20 years. • Although many of the newer systems have done away with the serial port completely in favor of USB connections, most modems still use the serial port, as do some printers, PDAs and digital cameras. Few computers have more than two serial ports.

35. Parallel Ports • If you have a printer connected to your computer, there is a good chance that it uses the parallel port. While USB is becoming increasingly popular, the parallel port is still a commonly used interface for printers. Parallel ports can be used to connect a host of popular computer peripherals: • Printers • Scanners • CD burners • External hard drives • Iomega Zip removable drives • Network adapters • Tape backup drives

36. Universal Serial Bus (USB) Ports The goal of USB is to end all of these headaches. The Universal Serial Bus gives you a single, standardized, easy-to-use way to connect up to 127 devices to a computer. Just about every peripheral made now comes in a USB version. A sample list of USB devices that you can buy today includes: PrintersScannersMiceJoysticks Flight yokes Digital camerasWebcams Scientific data acquisition devices ModemsSpeakersTelephones Video phones Storage devices such as Zip drives Network connections Connecting a USB device to a computer is simple -- you find the USB connector on the back of your machine and plug the USB connector into it.

37. A typical "B" connection The rectangular socket is a typical USB socket on the back of a PC. A typical USB connector, called an "A" connection

38. Power supply An electrical transformer regulates the electricity used by the computer. Hard disk This is large-capacity permanent storage used to hold information such as programs and documents. Operating system This is the basic software that allows the user to interface with the computer.

39. Secondary Memory • Secondary storage is also know as auxiliary memory, this memory is non-volatile. • Secondary memory can store large volume of data on a permanent basis

40. Secondary Storage Devices Direct Access Device Sequential Access Device Magnetic Tape Magnetic Disks Optical Disks CD-ROM Floppy Disk Hard Disk

41. Characteristics of Storage Device • The four most important characteristics of storage devices: • Speed and access time • Capacity • Type of access

42. Speed (Access time) - How fast information can be taken from or stored onto the computer memory device’s medium. • Electronic circuits: Fastest to access. • 40 billionths of a second. • Floppy disks: Very slow in comparison. • Takes up to 1/2 second to reach full speed before access is even possible.

43. Capacity – The amount of information that can be stored on the medium. Unit Description Approximate Size 1 bit 1 binary digit 1 nibble 4 bits 1 byte 8 bits 1 character 1 kilobyte 1,024 bytes 1/2 page, double spaced 1 megabyte 1,048,576 bytes 500,000 pages 1 million bytes 1 gigabyte 1,073,741,824 bytes 5 million pages 1 billion bytes 1 terabyte 1 trillion bytes 5 billion pages

44. There are two methods of accessing information- • Sequential access • Direct access • Sequential Access: • Information on a sequential access device can only be retrieved in the same sequence in which it is stored. For example: preparation of monthly pay slips, monthly electricity bills etc. • Magnetic tape is an example of a sequential-access storage device. • The magnetic tape is a plastic ribbon, ½ -1/4 inch wide and 50-2400 feet long. The tape ribbon is itself stored in small cartridge or cassette.

45. Direct Access: • Information on a direct access device can be retrieved randomly. • Magnetic disk is the storage medium for direct access • Magnetic disk is broadly classified into 2 types: • Floppy Disk • Hard Disk

46. Floppy Disk: • A floppy disk is a circular piece of oxide-coated plastic that stores data as magnetic spots. Personal computers most commonly use floppy disks that are 3 ½ inches in diameter. • A Floppy disk drive is used to read/write data from /to floppy disks. • Hard Disk • Hard Disk is the secondary storage device, which are made of rigid metal.

47. Optical Disks: CD-ROM and DVD • CD-ROM (Compact Disk - Read Only Memory) • By its definition, CD-ROM is Read Only. • Special CD drives “burn” information into blank CDs. • Burn: A laser is used to “burn” craters into the surface to represent a binary 1. • Two main types of CDs: • CD-R (Compact Disk - Recordable) • CD-WR (Compact Disk - ReWritable) • It takes longer to write to a CD-R than a hard drive. • Special software is needed to record.

48. DVD (Digital Versatile Disk) • Allows up to 17 gigabytes of storage (from 4.7 GB to 17 GB). • Compatible with older CD-ROM technology.

49. Types of Computer Hand-held Computer A hand-held computer or personal organizer is a small portable computer with various functions, for example diary, phone book, note book, etc. Personal Computer PC or desktop computers are used both in isolation, for example in home computing, and as networked computers (a network is two computers or more that are linked together either by cabling or infra-red).

50. Palmtop • More commonly known as Personal Digital Assistants (PDAs), palmtops are tightly integrated computers that often use flash memory instead of a hard drive for storage. • These computers usually do not have keyboards but rely on touchscreen technology for user input • Workstation • A desktop computer that has a more powerful processor, additional memory and enhanced capabilities for performing a special group of task, such as 3D Graphics or game development.