Maintenance of Computer System

1. Maintenance of Computer System Electronics & Communication Engineering Deptt Seth Jai parkash Polytechnic Damla

2. Computer Hardware Maintenance Outline: • Introduction to computer hardwares • Basic operations • Motherboard • Processor • RAM & ROM • Ports & Cabling • Connectors & Expansion Card • Storage & Hard Drives • Power Supply • Types of printers

3. Graphic Representation of Computer Components:

4. Motherboard • The motherboard is the main circuit board of a microcomputer. It contains the central processing unit (CPU), the Basic Input/Output System (BIOS), memory, mass storage interfaces, serial and parallel ports, expansion slots, and all the controllers for standard peripheral devices like the keyboard, disk drive and display screen. • BIOS stands for Basic Input/Output System. It is the lowest-level software in the computer; it acts as an interface between the hardware (especially the chipset and processor) and the operating system. The BIOS provides access to the system hardware and enables the creation of the higher-level operating systems that you use to run your applications. • The BIOS is also responsible for allowing you to control your computer's hardware settings, for booting up the machine when you turn on the power or hit the reset button, and various other system functions.

5. ATXMOTHERBOARD ATX

6. Inside the Processor • The CPU has 2 fundamental sections: the Control Unit, and the Arithmetic Logic Unit. These work together to perform processing operations. • Fundamentally all processors do the same thing. They take signals in the form of 0s and 1s (thus binary signals), manipulate them according to a set of instructions, and produce output in the form of 0s and 1s. The voltage on the line at the time a signal is sent determines whether the signal is a 0 or a 1. On a 3.3-volt system, an application of 3.3 volts means that it's a 1, while an application of 0 volts means it's a 0. • Other components of the CPU include the Registers and the System Clock. A processor’s clock speed is measured in Megahertz (MHz) and Gigahertz (GHz). Clock speed is the speed at which a processor executes instructions. A Pentium IV typically has a clock speed of 1.4 GHz. Further research: Buses, System Bus, Expansion Bus

7. Random Access Memory (RAM) • RAM is Primary Storage, also called internal storage. • Serves as computer’s workspace, storing all or part of the program that is being executed, as well as data being used by the program. • RAM stores the operating system programs that manage the operation of the computer. • RAM is Volatile storage: • Power goes, data goes! • More memory = larger workspace • Large programs = large number of instructions • Measured in Bytes (KB, MB, GB, etc.) • Data/instructions are copied into memory as needed. • Not enough memory or corruption of data/instructions in memory can cause crash. • LATEST AVAILABLE RAM ID DDR4 CATEGORY

8. BIOS • Flash memory is reprogrammable memory. You can upgrade the logic capabilities by simply downloading new software. This saves the expense of replacing circuit boards and chips. • EEPROM chips contain permanently written data, called firmware (your BIOS lives here). • EEPROM contains the programs that direct the computer to load the operating system and related files when the computer is powered on. • EEPROM chips are usually recorded when they’re manufactured.

9. PORTS • On computer, a port is generally a specific place for being physically connected to some other device, usually with a socket or plug which we call Connectors Typical Computer Port found behind a desktop PC

10. CONNECTORS • A connector is any connector used within computers or to connect computers to networks, printers or other devices. Many types of computer connectors

11. PS/2 Connector • The PS/2 connector are use for connecting keyboard and mouse on the modern PCs. The PS2 mouse connector and port is usually green in colour to distinguish it from the PS2 keyboard, which is purple. It is 6 pin round shape connector

12. USB Port • Universal Serial Bus: a protocol for transferring data to and from digital devices. • Many digital cameras and memory card readers connect to the USB port on a computer. • It is also known as Hotswappable port

13. Firewire IEEE 1394 Port • A type of cabling technology for transferring data to and from digital devices at high speed. FireWire are typically faster than those that connect via USB.

14. RJ45 Ethernet Port • LAN or (Local Area Network) uses a CAT6 cable and a RJ45 connection. The CAT 6 cable  is also called the Ethernet Cable. • Network connection generally uses a 10/100 Mbps/1Gbps speed.

15. DB25 Parallel Port • The printer connects to computer with a Parallel connector. This connector has 25 pins. • Parallel means the device is capable of receiving more than one bit at a time (that is, it receives several bits in parallel). • It is also termed as LPT

16. Ports and Connectors

17. Expansion Cards • Expansion Cards plug into the expansion slots found on the motherboard.Convenient way to add extra ports or expand the computer’s capabilities. Accelerated Graphics Port (AGP) Peripheral Component Interconnect (PCI)

18. Expansion Slots and Cards • Various type of expansion slots are: • Peripheral Component Interconnect (PCI) • Accelerated Graphics Port (AGP) • Industry Standard Architecture (ISA) (obsolete category) • Universal Serial Bus (USB) • Small Computer System Interface (SCSI) • Integrated Drive Electronics (IDE) • Expansion slots are sockets to provide direct connections to the common electrical bus, allowing you to insert a circuit board into the motherboard. • Typical Expansion Cards: • Video Cards • Sound Cards • Modem Cards • Network Interface Cards (NIC) • PCI and PCI-e are the latest architecture used in todat computers

19. Printers Impact Printers Non-Impact Printers Daisy wheel Dot- Matrix Inkjet Laser

20. What is a printer? • An external hardware device responsible for taking computer data and generating a hard copy of that data. Printers are one of the most commonly used peripherals and they print text and still images on the paper.

21. “Impact Printer Working” • These printers have a mechanism that touches the paper to create an image. • These printers work by banging a print head containing a number of metal pins which strike an inked ribbon placed between the print head and the paper.

22. “Non-Impact Printers” • These printers create an image on the print medium without the use of force. They don’t touch the paper while creating an image. Non-impact printers are much quieter than impact printers as they don’t strike the paper.

23. “Dot Matrix Printer” • Working :-The term dot matrix refers to the process of placing dots to form an image. • Limitation:-This is the cheapest and the most noisy printer and has a low print quality.

24. “Advantages/Dis-advatages of Dot-Matrix” • Advantages: • (1) In-expensive. • (2) Low per page cost. • (3) Energy efficient. • Dis-advantages: • (1) Noisy • (2) Low resolution • (3) Limited fonts flexibility • (4) Poor quality graphics output.

25. “Ink-Jet Printer” • It is a non-impact printer producing a high quality print. • It uses nozzles instead of pins • It spray ink from these nozzles

26. How Inkjet Printer works? • (1) Print head having four ink cartridges moves . • (2) Software instructs where to apply dots of ink, which color and what quantity to use.

27. Advantages/ Dis-advantages • Advantages: • (1) High resolution output. • (2) Energy efficient. • (3) Many options to select. • Dis-advantages: • (1) Expensive. • (2) Special paper required for higher resolution output. • (3) Time consuming in case of graphics printing.

28. “Laser Printer” • Laser printers used for image formation process. • In Laser printer we have cartridge containing toner. • A drum contained in elctrophotographiccartrige.

29. Network Devices

30. Hubs • Intelligent hubs have console ports, to allow monitoring of the hubs status and port activity. • Passive hubs just repeat any incoming signals to every port available, therefore does not act as a line repeater. • Passive hubs just split signals to multiple ports but do not regenerate the signals, which means that they do not extend a cable’s length. They only allow two or more hosts to connect to the same cable segment. • Active hubs regenerate signals. • Hubs utilise star topology.

31. Hub Pros & Cons • Advantages • As an active hubs regenerate signals, it increases the distance that can be spanned by the LAN (up to 100 meters per segment). • Hubs can also be connected locally to a maximum of two other hubs, thereby increasing the number of devices that can be attached to the LAN. • Disadvantages • Bandwidth is shared by all hosts i.e. 10Mbs shared by 25 ports/users. • Can create bottlenecks when used with switches. • Have no layer 3 switching capability. • .

32. Switches • A switch is a multi-port bridge. • It operates at OSI data link layer 2. • It stores MAC addresses in an internal lookup table. • Temporary switched paths are created between the frame’s source destination. • Some Switches have limited layer 3 IP routing capabilities. • Switches can be configured to use VLANS. • Switches support spanning tree protocol to create resilient networks.

33. UTP 10Mbs Hub Fibre 100Mbs Switch Example Topology

34. UTP Co-axial Transceiver Modules • Connects to any Auxiliary Unit Interface port (AUI). • Operates at OSI layer 1. • Allows multiple media types to connect to an Ethernet device. i.e. fibre ST/SC,Co-ax cable, and UTP.

35. Routers • Routers are OSI network layer 3 devices • Using interface modules can connect different layer 2 technologies e.g. Ethernet, FDDI, token ring etc… • Routers have the capability to interconnect network segments or entire networks (WANS/MANS). • These devices examine incoming packets to determine the destination address of the data. It then examines its internal routing table to choose the best path for the packet through the network, and switches them to the proper outgoing port.

36. Example Router Topology

37. Data Transmission and Modems

38. Agenda • Circuit • Mode of transmission • Digital transmission • Analog transmission for digital signals - modems • Methods • Classification • Interfaces • Functions • Selection Criteria

39. Circuit • Signal rate • No. of signal changes (amplitude, frequency, or phase) on a circuit per second • Baud • Types: dibits, tribits, and quadbits • Speed • No. of bits that a circuit can carry in 1 second • Bits per second (bps) used for measurement

40. Mode of Transmission • Data flow • Physical connection • Timing

41. Data Flow - US • Simplex transmission • Television and radio • Half-duplex (HDX) transmission • CB radio, terminal • Full-duplex (FDX) transmission • Telephone, computer to computer

42. Physical Connection • Parallel transmission • Fast • Simple • Line cost • Serial transmission • Complicated transmitter and receive • Decomposing and reconstructing

43. Timing • Asynchronous transmission • Start/stop bits for character synchronization • Mark (1or stop) /space (0 or start ) bits for bit synchronization • Simple, inexpensive, slow speed transmission • For personal computer • Synchronous transmission • Clock circuitry • One to four synchronization characters for each block of data • Large amount of data on dedicated line

44. Digital Signals • Unipolar (positive voltage for 1, no voltage for 0) • Bipolar, nonreturn-to zero (NRZ) • Manchester coding (low-to-high is 1, high-to- low is 0) • Differential Manchester (no transition at the beginning of the bit period is 1, second transition at the beginning of the bit period is 0) • Benefits: self-clocking, and error detection • Bipolar, return-to-zero

45. Benefits of Digital Transmission • Better data integrity (detect & correct error) • Higher capacity cables (fiber-optic) • Easier integration (voice, data, video, etc.) • Better security and privacy (encrypt data) • Lower cost (large-scale integrated circuitry)

46. Digital Transmission of Analog Signals • Quantization • Quantizing noise or digitizing distortion • Codec (coder/decoder): analog-to-digital (A/D) converter & digital-to-analog (D/A) converter • Methods • Pulse code modulation (256 integers, 8000 per second) • Adaptive differential pulse code modulation (difference) • Delta modulation (1 for +, 0 for -)

47. Digital Transmission of Digital Signals • Digital transmitter/receiver (data service unit/channel service unit (DSU/CSU)) • Simpler & cheaper • Transmitter for shaping & timing the signal, interface between DTE and line • Receiver for protection of excessive voltage, diagnostic and testing

48. Analog Transmission of Digital signals (Modems – I) • Modulation and Demodulation • Receiver (modulation), control unit (auto dial & auto answer), transmitter (demodulation), & power supply • Equalizer in transmitter & adaptive equalizer in receiver (adjust to fit the characteristics of the telephone line) • Methods • Frequency shift keying (FSK) • Phase shift keying (PSK): 180 degree (1 bit), 90 degree (2 bits), 45 degree (3 bits) • Differential phase shift keying (DPSK) • Quadrature amplitude modulation (QAM): combination of 8 phases & 4 relative amplitudes

49. Modem Classification • Simplex, half-duplex, full-duplex transmission modems • Asynchronous or synchronous transmission modems • Acoustically coupled modems (portable) • Limited distance modems/short haul modems (less than 20 miles) • Modem eliminators/null modems (cable less than several thousand feet)

50. Modem Classification - II • Facsimile modems • Error correction and data compression • Modem for fiber-optics circuits • Digital-electrical to digital-optical • Cable modems • DTE to cable television system cable • Data Over Cable Service Interface Specification (DOCSIS) by CableLabs • For large files and not logon process