Introduction To HardwareThe interior of a computer looks very complicated at first glance. When the case is removed there is a mass of bits, cables and components that can intimidate the uninitiated. This lesson will seek to dispense some of the mist that may surround the hardware of a computer.

Motherboards

The most important part of any computer is the motherboard. As the name implies a motherboard is the mother of all other components in a computer.

The motherboard brings all the core components together such as the Central Processing Unit (CPU), Memory and Hard Disks. In short, the motherboard connects and allows all of the components in the computer to work together.

There are two different types of Motherboard: AT style and ATX style.

AT Motherboards

The AT-style motherboards represent the classic approach to component placement. AT-motherboards are available in two variations, the baby AT and the full AT. Both variations simply refer to the overall dimensions of the board.

AT Boards are generally found in older systems, typically those that use the now aged Pentium Processor. The Majority of AT motherboards had a single keyboard port soldered to the motherboard

The I/O ports (e.g. USB, COM and PS/2 ports) are separate from the motherboard and are placed on a riser card or separate headers.

To identify an AT motherboard first check the power connectors. AT Motherboards use two sets of 6-pin inline power connectors

Caution it is possible to plug these connectors in the wrong order and fuse the motherboard

ATX Motherboards

The ATX-style motherboards are a result of the industry’s push for standardization and are found in most systems today. Most modern computers contain an ATX motherboard. ATX boards can use Advanced Power Management.

Distinguished by having more than just one external connector ATX boards have Keyboard, Mouse, Serial, Parallel and USB connectors.

ATX boards can also be distinguished by the monoblock power connectors. Also available in micro ATX enabling the use of smaller cases.

Motherboard Components

There are two types of receivers for CPU’s

Zero insertion force or ZIF sockets. With a ZIF socket, before the CPU is inserted, a lever or slider on the side of the socket is moved, pushing all the sprung contacts apart so that the CPU can be inserted with very little force (generally the weight of the CPU itself is sufficient with no external downward force required). The lever is then moved back, allowing the contacts to close and grip the pins of the CPU, often with a fan attached for cooling.

Single Edged Contact (SEC) cartridge slot or Slot 1 seen on PII and PIIIs. Developed by Intel to add Cache memory for the processor cheaply. The processor is mounted on a Single Edge Connector Cartridge (SECC), much like a PCI slot, but with a 242-lead edge-connector.

Bridges

There are two main bridges on a motherboard the Northbridge and the Southbridge. Bridges control access to the processor from the peripherals.

The Northbridge, also known as the Memory Controller Hub (MCH), is traditionally one of the two chips in the core logic chipset on a PC motherboard. The Northbridge typically controls communications between the CPU, RAM, AGP or PCI Express, and the Southbridge.. A Northbridge will typically work with only one or two classes of CPUs and generally only one type of RAM. There are a few chipsets that support two types of RAM (generally these are available when there is a shift to a new standard).

The Southbridge, also known as the I/O Controller Hub (ICH), is a chip that implements the “slower” capabilities of the motherboard in a Northbridge Southbridge chipset computer architecture. The Southbridge can usually be distinguished from the Northbridge by not being directly connected to the CPU. Rather, the Northbridge ties the Southbridge to the CPU. The functionality found on a contemporary Southbridge includes:PCI bus, ISA bus, SMBus, DMA controller, Interrupt controller, IDE, (SATA or PATA) controller ,LPC Bridge, Real Time Clock, Power management (APM and ACPI) and Nonvolatile BIOS memory

BIOS Chips

The [[BIOS( Basic Input Output System)]] refers to the software code run by a computer when first powered on. The primary function of BIOS is to prepare the machine so other software programs stored on various media (such as hard drives, floppies, and CDs) can load, execute, and assume control of the computer. This process is known as booting up.

The BIOS is stored as a ROM (Read-Only Memory) program and is retained when the machine is turned off. Settings within the BIOS may be changed by the user and these changes are stored in the BIOS memory this is maintained by a trickle of charge from the BIOS battery.

Memory

SIMMS- Single Inline Memory Modules. An older type of memory only seen on very old motherboards came in 30 pin modules and 72 pin modules.

SDRAM chips are rated according to their maximum clock rate and their read cycle time. Common clock ratings include 66MHz, 100MHz, and 133MHz. Common read cycle times include 50ns and 60ns.

DDR SDRAM or double-data-rate synchronous dynamic random access memory is a type of memory integrated circuit used in computers. It achieves greater bandwidth than ordinary SDRAM by transferring data on both the rising and falling edges of the clock signal (double pumped). This effectively nearly doubles the transfer rate without increasing the frequency of the front side bus.

Stick/module specificationPC-1600: DDR-SDRAM memory module specified to operate at 100 MHz using DDR-200 chips, 1.600 GByte/s bandwidthPC-2100: DDR-SDRAM memory module specified to operate at 133 MHz using DDR-266 chips, 2.133 GByte/s bandwidthPC-2700: DDR-SDRAM memory module specified to operate at 166 MHz using DDR-333 chips, 2.667 GByte/s bandwidthPC-3200: DDR-SDRAM memory module specified to operate at 200 MHz using DDR-400 chips, 3.200 GByte/s bandwidth

Drive Connectors

Integrated Device Electronic (IDE)

[Integrated Device Electronic (IDE)]] connectors connect the motherboard, via a ribbon cable to various peripherals, the most common being hard drives and CD ROMs. On most boards there are 2 channels/connectors, each can have 2 devices attached giving a total of four IDE devices.

If one device is attached to a cable, it should be configured as the master. If two devices are attached to the same cable then one must be the master device and one the slave. Master and slave are configured by the use of jumpers. Jumpers are small, insulated sleeves with a contact inside used to complete a circuit

Hard Disks

Hard disks are used to store data in a non-volatile form within the machine. I.e. the data remains intact even if the power to the device is cut off. Data is stored as magnetic ones and zeros on a steel platen and is read by pickup arms that scan the drive as the platens spin

Most major hard drive and motherboard vendors now support self-monitoring, analysis, and reporting technology (S.M.A.R.T.), by which impending failures can be predicted, allowing the user to be alerted to prevent data loss.The mostly sealed enclosure protects the drive internals from dust, condensation, and other sources of contamination. The hard disk’s read-write heads fly on an air bearing which is a cushion of air only nanometers above the disk surface. The disk surface and the drive’s internal environment must therefore be kept immaculate to prevent damage from fingerprints, hair, dust, smoke particles, etc., given the submicroscopic gap between the heads and disk.

Floppy Disks

The floppy disc controller is generally situated near the IDE controllers and in fact looks like a small IDE slot

The ribbon has a twist and the first floppy drive (A: drive) should be placed after the twist if the cable has more than three connectors. If the cable is really old it may have a connector for a 5 1/4 Floppy drive.

SCSI

SCSI stands for “Small Computer System Interface”, and is a standard interface and command set for transferring data between devices on both internal and external computer buses. SCSI is most commonly used for hard disks and tape storage devices, but also connects a wide range of other devices, including scanners, printers, CD-ROM drives, CD recorders, and DVD drives. In fact, the entire SCSI standard promotes device independence, which means that theoretically SCSI can be used with any type of computer hardware.

On a parallel SCSI bus, a device (e.g. host adapter, disk drive) is identified by a “SCSI ID”, which is a number in the range 0-7 on a narrow bus and in the range 0-15 on a wide bus.

SATA

Serial ATA (SATA) is a computer bus technology primarily designed for transfer of data to and from a hard disk. It is the successor to the legacy AT Attachment standard (ATA).

This older technology was retroactively renamed Parallel ATA (PATA) to distinguish it from Serial ATA. Both SATA and PATA drives are IDE (Integrated Drive Electronics) drives, although IDE is often misused to indicate PATA drives.

The two SATA interfaces, SATA/150, runs at 1.5 GHz resulting in an actual data transfer rate of 1.2 Gigabits per second (Gb/s), or 150 megabytes per second (MB/s). SATA II 3Gb/s resulting in an actual data transfer rate of 2.4 Gb/s, or 300 MB/s.

Motherboard Slots

To add more functionality to a computer, cards such as network or video cards can be added. Sometimes these functions are built into the motherboard. There are several types of expansion slots:

The PCI (Peripheral Component Interconnect) The PCI bus is common in modern PCs, where it has displaced ISA as the standard expansion bus, but it also appears in many other computer types.PCI 2 33.33 MHz clock with synchronous transfers peak transfer rate of 133 MB per second for 32-bit busPCI 2.2 allows for 66 MHz signalling (requires 3.3 volt signalling) (peak transfer rate of 503 MB/s) PCI 2.3 permitted use of 3.3 volt and universal keying, but did not support 5 volt keyed add in cards.PCI 3.0 is the final official standard of the bus, completely removing 5 volt support.

ISA/EISA; Industry Standard Architecture and Extended Industry Standard Architecture An older type of bus connector. Considered obsolete

PCI Express, PCIe, or PCI-E is an implementation of the PCI computer bus that uses existing PCI programming concepts, but bases it on a completely different and much faster serial physical-layer communications protocol. PCIe transfers data at 250 MB/s (238 MiB/s), per channel to a maximum of 16 channels, a total combined transfer rate of 4GB/s (3.7 GiB/s). Almost all of the high end graphics cards being released today use PCI Express. NVIDIA uses the high-speed data transfer of PCIe for its newly developed

Scalable Link Interface (SLI) technology, which allows two graphics cards of the same chipset and model number to be run at the same time, allowing increased performance.

The Accelerated Graphics Port (also called Advanced Graphics Port) is a high-speed point-to-point channel for attaching a graphics card to a computer’s motherboard, primarily to assist in the acceleration of 3D computer graphics. Some motherboards have been built with multiple independent AGP slots. AGP is slowly being phased out in favour of PCI Express.

AGP 1x, using a 32-bit channel operating at 66 MHz resulting in a maximum data rate of 266 megabytes per second (MB/s), doubled from the 133 MB/s transfer rate of PCI bus 33 MHz / 32-bit; 3.3 V signaling.AGP 2x, using a 32-bit channel operating at 66 MHz double pumped to an effective 133 MHz resulting in a maximum data rate of 533 MB/s; signaling voltages the same as AGP 1x;AGP 4x, using a 32-bit channel operating at 66 MHz quad pumped to an effective 266 MHz resulting in a maximum data rate of 1066 MB/s (1 GB/s); 1.5 V signaling;AGP 8x, using a 32-bit channel operating at 66 MHz, strobing eight times per clock, delivering an effective 533 MHz resulting in a maximum data rate of 2133 MB/s (2 GB/s); 0.8 V signaling.

Peripheral Connections

There are a number of ports on the motherboard for the connection of additional devices:.

Serial ports connected the computer to devices such as terminals or modems. Mice, keyboards, and other peripheral devices also connected in this way.

Parallel ports are most often used to communicate with peripheral devices. The most common kind of parallel port is a printer port, such as a Centronics connector based port which transfers eight bits at a time. Disk drives are also connected via special parallel ports, such as those used by the SCSI and ATA technlogies. However, when people refer to a parallel port, they are usually referring to a printer port, either on a printer or a PC.

A USB system has an asymmetric design, consisting of a host controller and multiple daisy-chained devices. Additional USB hubs may be included in the chain, allowing branching into a tree structure, subject to a limit of 5 levels of branching per controller. No more than 127 devices, including the bus devices, may be connected to a single host controller. Modern computers often have several host controllers, allowing a very large number of USB devices to be connected. USB cables do not need to be terminated.

USB supports three data rates.A Low Speed rate of 1.5 Mbit/s (183 KiB/s) that is mostly used for Human Interface Devices (HID) such as keyboards, mice, and joysticks.A Full Speed rate of 12 Mbit/s (1.5 MiB/s). Full Speed was the fastest rate before the USB 2.0 specification and many devices fall back to Full Speed. Full Speed devices divide the USB bandwidth between them in a first-come first-served basis and it is not uncommon to run out of bandwidth with several isochronous devices. All USB Hubs support Full Speed.A Hi-Speed rate of 480 Mbit/s (57 MiB/s).

Introduction to NetworkingWhy use a Network?

Quite simply explained we use networks for communication between computers, sharing of data and peripherals. In the business world we use networks for ease of administration and to cut costs.

Sharing data example imagine an office with 5 secretaries working on 5 different computers, one requires a file from another computer in a non networked office this file would have to be written to a portable media then loaded onto the computer. In a networked office the file could be accessed via the network from a shared folder.

Sharing peripherals example the same office with 5 secretaries working on 5 different computers, in order to print their work each computer would need to have a printer attached. In a networked office you could have one shared printer, cutting costs.

What do you need?A common language or protocol (TCP/IP IPX/SPX, APPLE TALK) is a convention or standard that controls or enables the connection, communication, and data transfer between two computing endpoints.

A common language or protocol (TCP/IP IPX/SPX, APPLE TALK) is a convention or standard that controls or enables the connection, communication, and data transfer between two computing endpoints.

Cabling BNC,Cat5, fibre optic

Hardware NIC(Network Interface Card), router, switch, hub, modem wireless access point.

Network Service (DNS, WINS, DHCP).

Network HardwareNetwork Interface Card

A network card, network adapter, network interface card or NIC is a piece of computer hardware designed to allow computers to communicate over a computer network. It has a MAC address. Every network card has a unique 48-bit serial number called a MAC address, which is written to ROM carried on the card. Every computer on a network must have a card with a unique MAC address. The IEEE is responsible for assigning MAC addresses to the vendors of network interface cards. No two cards ever manufactured should share the same address.

Hubs

An Ethernet hub or concentrator is a device for connecting multiple twisted pair or fibre optic Ethernet devices together, making them act as a single segment. It works at the

physical layer of the OSI model, repeating the signal received at one port out each of the other ports (but not the original one). The device is thus a form of multiport repeater. Ethernet hubs are also responsible for forwarding a jam signal to all ports if it detects a collision. Hubs also often come with a BNC and/or AUI connector to allow connection to legacy 10BASE2 or 10BASE5 network segments. The availability of low-priced Ethernet switches has largely rendered hubs obsolete but they are still seen in older installations and more specialist applications.

Switches

A network switch or switch for short is a networking device that performs transparent bridging (connection of multiple network segments with forwarding based on MAC addresses) at full wire speed in hardware. As a frame comes into a switch, the switch saves the originating MAC address and the originating (hardware) port in the switch’s MAC address table. This table often uses content-addressable memory, so it is sometimes called the “CAM table”. The switch then selectively transmits the frame from specific ports based on the frame’s destination MAC address and previous entries in the MAC address table. If the destination MAC address is unknown, for instance, a broadcast address or (for simpler switches) a multicast address, the switch simply transmits the frame out of all of the connected interfaces except the incoming port. If the destination MAC address is known, the frame is forwarded only to the corresponding port in the MAC address table.

Hubs VS Switches

A hub, or repeater, is a fairly unsophisticated broadcast device. Any packet entering any port is broadcast out on every port and thus hubs do not manage any of the traffic that comes through their ports. Since every packet is constantly being sent out through every port, this results in packet collisions, which greatly impedes the smooth flow of traffic. A switch isolates ports, meaning that every received packet is sent out only to the port on which the target may be found (assuming the proper port can be found; if it is not, then the switch will broadcast the packet to all ports except the port the request originated from). Since the switch intelligently sends packets only where they need to go the performance of the network can be greatly increased.

Routers

A router is a computer networking device that forwards data packets across a network toward their destinations, through a process known as routing. A router acts as a junction between two or more networks to transfer data packets among them. A router is different from a switch. A switch connects devices to form a Local area network (LAN).

One easy illustration for the different functions of routers and switches is to think of switches as local streets, and the router as the junctions with the street signs. Each house on the local street has an address within a range on the street. In the same way, a switch connects various devices each with their own IP address(es) on a LAN. Routers connect networks together the way that on-ramps or major junctions connect streets to both main roads and motorways. The street signs at the junctions the (routing table) show which way the packets need to flow.

Wireless

Wireless Access Point (WAP) A wireless access point (AP) connects a group of wireless stations to an adjacent wired local area network (LAN). An access point is similar to an Ethernet hub, but instead of relaying LAN data only to other LAN stations, an access point can relay wireless data to all other compatible wireless devices as well as to a single (usually) connected LAN device, in most cases an Ethernet hub or switch, allowing wireless devices to communicate with any other device on the LAN.

Wireless Routers A wireless router integrates a wireless access point with an Ethernet switch and an Ethernet router. The integrated switch connects the integrated access point and the integrated Ethernet router internally, and allows for external wired Ethernet LAN devices to be connected as well as a (usually) single WAN device such as a cable modem or DSL modem. A wireless router advantageously allows all three devices (mainly the access point and router) to be configured through one central configuration utility, usually through an integrated web server. However one disadvantage is that one may not decouple the access point so that it may be used elsewhere.

Cables

Cable Terminology

10BASE2 (also known as cheapernet or thinnet) is a variant of Ethernet that uses thin coaxial cable. The 10 comes from the maximum transmission speed of 10 Mbit/s (millions of bits per second). The BASE stands for baseband signaling, and the 2 represents a rounded up shorthand for the maximum segment length of 185 metres (607 feet).

10BASE5 (also known as thicknet) is the original “full spec” variant of Ethernet cable. The 10 refers to its transmission speed of 10 Mbit/s. The BASE is short for baseband signalling as opposed to broadband, and the 5 stands for the maximum segment length of 500 metres.

10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. The name 10BASE-T is derived from several aspects of the physical medium. The 10 refers to the transmission speed of 10 Mbit/s. The BASE is short for baseband.The T comes from twisted pair, which is the type of cable that is used

100BASE-T is any of several Fast Ethernet 100 Mbit/s CSMA/CD standards for twisted pair cables, including: 100BASE-TX (100 Mbit/s over two-pair Cat5 or better cable). The segment length for a 100BASE-T cable is limited to 100 metres

Coaxial

Coaxial cable is an electrical cable consisting of a round conducting wire, surrounded by an insulating spacer, surrounded by a cylindrical conducting sheath, usually surrounded by a final insulating layer. It is used as a high-frequency transmission line to carry a high-frequency or broadband signal.

BNC connectors were commonly used on 10base2 thin Ethernet networks, both on cable interconnections and network cards, though these have largely been replaced by newer Ethernet devices whose wiring does not use coaxial cable.

CAT 5

Category 5 cable, commonly known as Cat 5, is an unshielded twisted pair cable type designed for high signal integrity. Category 5 has been superseded by the Category 5e

specification. This type of cable is often used in structured cabling for computer networks such as Gigabit Ethernet, although they are also used to carry many other signals such as basic voice services, token ring.

Category 5 cable included four twisted pairs in a single cable jacket. It was most commonly used for 100 Mbit/s networks, such as 100BASE-TX Ethernet

Cat5 cable uses an RJ-45 (Registered Jack-45) connector at each end of the cable with a fixed wiring scheme. The ends are then crimped on to the cable

Wiring Scheme

Patch or straight through cables have Wiring scheme 1 at both ends of the cable and are used to connect computers to network wall sockets or hubs.

Crossover cables have Wiring scheme 1 at one end of the cable and Wiring scheme 2 at the other. These cables are used to connect network hardware together e.g. PC to PC, hub to hub.

ProtocolsA protocol (TCP/IP IPX/SPX, APPLE TALK) is a convention or standard that controls or enables the connection, communication, and data transfer between two computing endpoints. Sending and receiving systems need to use the same protocol unless a gateway service sits between networks and translates from one to the other.

Most protocols specify one or more of the following properties:

Detection of the underlying physical connection (wired or wireless), or the existence of the

other endpoint or node

Handshaking

Negotiation of various connection characteristics

How to start and end a message

How to format a message

What to do with corrupted or improperly formatted messages (error correction)

How to detect unexpected loss of the connection, and what to do next

Termination of the session or connectioNetBIOS

NetBIOS is an acronym for Network Basic Input/Output System. The NetBIOS API allows applications on separate computers to communicate over a local area network. NetBIOS must be enabled for Windows File and Print Sharing to work.

NetBIOS provides three distinct services:

Name service for name registration and resolution

Session service for connection-oriented communication

Datagram distribution service for connectionless communication.

Name service In order to start Sessions or distribute Datagrams, an application must register its NetBIOS name using the Name service. NetBIOS names are 16 bytes in length

Session service Session mode lets two computers establish a connection for a “conversation,” allows larger messages to be handled, and provides error detection and recovery. In NBT, the session service runs on TCP port 139.

Datagram distribution service Datagram mode is “connectionless”. Since each message is sent independently, they must be smaller; the application becomes responsible for error detection and recovery. In NBT, the datagram service runs on UDP port 138.

IPX/SPX (NWLINK)

Internetwork Packet Exchange (IPX) is the OSI-model Network layer protocol in the IPX/SPX protocol stack. The IPX/SPX protocol stack is supported by Novell’s NetWare network operating system. Because of Netware’s popularity through the late 1980s into the mid 1990s, IPX became a popular internetworking protocol. Novell derived IPX from Xerox Network Services’ IDP protocol. IPX usage is in general decline as the boom of the Internet has made TCP/IP nearly universal. Computers and networks can run multiple network protocols, so almost all IPX sites will be running TCP/IP as well to

allow for Internet connectivity. It is also now possible to run Novell products without IPX, as they have supported both IPX and TCP/IP since NetWare reached version 5.

Sequenced Packet Exchange (SPX) is a transport layer protocol (layer 4 of the OSI Model) used in Novell Netware networks. The SPX layer sits on top of the IPX layer (layer 3 – the network layer) and provides connection-oriented services between two nodes on the network. SPX is used primarily by client/server applications.

NWLink is a IPX/SPX-compatible protocol developed by Microsoft and used in its Windows NT product line.NWLink is Microsoft’s version of Novell’s IPX/SPX Protocol. The Microsoft version of NWLink includes the same level of functionality as the Novell Protocol. NWLink includes a tool for resolving NetBIOS names.NWLink packages data to be compatible with client/server services on NetWare Networks. However, NWLink does not provide access to NetWare File and Print Services. To access the File and Print Services the Client Service for NetWare needs to be installed.

AppleTalk

AppleTalk is a suite of protocols developed by Apple Computer for computer networking. It was included in the original Macintosh (1984) and is now used less by Apple in favour of TCP/IP networking.

AppleTalk contains two protocols aimed at making the system completely self-configuring. The AppleTalk address resolution protocol (AARP) allowed AppleTalk hosts to automatically generate their own network addresses, and the Name Binding Protocol (NBP) was essentially a dynamic DNS system which mapped network addresses to user-readable names.

For interoperability Microsoft maintains the file services for Macintosh and the print services for Macintosh

TCP/IP

The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. It is sometimes called the TCP/IP protocol suite, after the two most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were also the

first two defined.The Internet protocol suite like many protocol suites can be viewed as a set of layers, each layer solves a set of problems involving the transmission of data, and provides a well-defined service to the upper layer protocols based on using services from some lower layers. Upper layers are logically closer to the user and deal with more abstract data, relying on lower layer protocols to translate data into forms that can eventually be physically transmitted.The OSI model describes a fixed, seven layer stack for networking protocols. Comparisons between the OSI model and TCP/IP can give further insight into the significance of the components of the IP suite, but can also cause confusion, as TCP/IP consists of only 4 layers.

The four layers in the DoD model, from bottom to top, are:

The Network Access Layer is responsible for delivering data over the particular hardware

media in use. Different protocols are selected from this layer, depending on the type of

physical network.

The Internet Layer is responsible for delivering data across a series of different physical

networks that interconnect a source and destination machine. Routing protocols are most

closely associated with this layer, as is the IP Protocol, the Internet’s fundamental protocol.

The Host-to-Host Layer handles connection rendezvous, flow control, retransmission of lost

data, and other generic data flow management. The mutually exclusive TCP and UDP

protocols are this layer’s most important members.

The Process Layer contains protocols that implement user-level functions, such as mail

delivery, file transfer and remote login.

Network ServicesDNS (Domain Naming System)

The Domain Name System (DNS) stores and associates many types of information with domain names, but most importantly, it translates domain names (computer hostnames) to IP addresses. It also lists mail exchange servers accepting e-mail for each domain. In providing a worldwide keyword-based redirection service, DNS is an essential component of contemporary Internet use.

The DNS pre-eminently makes it possible to attach easy-to-remember domain names (such as “es-net.co.uk”) to hard-to-remember IP addresses (such as 270.146.131.206). People take advantage of this when they recite URLs and e-mail addresses.

WINS (Windows Internet Naming Service)

Windows Internet Naming Service (WINS) is Microsoft’s implementation of NetBIOS Name Server (NBNS) on Windows, a name server and service for NetBIOS computer names. Effectively, it is to NetBIOS names what DNS is to domain names – a central mapping of host names to network addresses. However, the mappings have always been dynamically updated (e.g. at workstation boot) so that when a client needs to contact another computer on the network it can get its up-to-date DHCP allocated address. Networks normally have more than one WINS server and each WINS server should be in push pull replication; the favoured replication model is the hub and spoke, thus the WINS design is not central but distributed. Each WINS server holds a full copy of every other related WINS system’s records. There is no hierarchy in WINS (unlike DNS), but like DNS its database can be queried for the address to contact rather than broadcasting a request for which address to contact. The system therefore reduces broadcast traffic on the network, however replication traffic can add to WAN / LAN traffic.

DHCP (Dynamic Host Configuration Protocol)

The Dynamic Host Configuration Protocol (DHCP) automates the assignment of IP addresses, subnet masks, default routers, and other IP parameters. The assignment usually occurs when the DHCP configured machine boots up or regains connectivity to the network. The DHCP client sends out a query requesting a response from a DHCP server on the locally attached network. The DHCP server then replies to the client with its assigned IP address, subnet mask, DNS server and default gateway information.The assignment of the IP address usually expires after a predetermined period of time, at which point the DHCP client and server renegotiate a new IP address from the server’s predefined pool of addresses. Configuring firewall rules to accommodate access from machines who receive their IP addresses via DHCP is therefore more difficult because the remote IP address will vary from time to time. Administrators must usually allow access to the entire remote DHCP subnet for a particular TCP/UDP port. Most home routers and firewalls are configured in the factory to be DHCP servers for a home network. ISPs (Internet Service Providers) generally use DHCP to assign clients individual IP addresses.DHCP is a broadcast-based protocol. As with other types of broadcast traffic, it does not cross a router.

APIPA (Automatic Private IP Addressing)

If computers are unable to pick an address up from a DHCP server they use Automatic Private IP Addressing (APIPA). This means the computer will assign itself a random address between 169.254.0.1 – 169.254.254.254/16, allowing it to communicate with other clients who are also using APIPA.

Automatic Private IP Addressing (APIPA), this allows unknowledgeable users to connect computers, networked printers, and other items together and expect them to work. Without Zeroconf or something similar, a knowledgeable user must either set up special servers, like DHCP and DNS, or set up each computer by hand.

NetworksA Local Area Network (LAN) is a computer network covering a small local area, like a home, office, or small group of buildings such as a home, office, or college. Current LANs are most likely to be based on switched Ethernet or Wi-Fi technology running at 10, 100 or 1,000 Mbit/s.The defining characteristics of LANs in contrast to WANs (wide area networks) are: their much higher data rates; smaller geographic range; and that they do not require leased telecommunication lines.

A Personal Area Network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one person. The reach of a PAN is typically a few metres and may use Bluetooth, wireless or USB for connection.

A Wide Area Network (WAN) is a computer network covering a wide geographical area, involving a vast array of computers. This is different from personal area networks (PANs), metropolitan area networks (MANs) or local area networks (LANs) that are usually limited to a room, building or campus. The most well-known example of a WAN is the Internet. WANs are used to connect local area networks (LANs) together, so that users and computers in one location can communicate with users and computers in other locations.

Introduction To WindowsOperating Systems

The most important piece of software on any computer is the operating system. The operating system gives the framework upon which all other services and applications run. The majority of home users use a Windows based machine. Most of today’s applications and games are designed to run solely on Microsoft systems.

Microsoft Windows is extremely popular in schools and colleges, many businesses also use Windows.

Introduction to Microsoft WindowsThe oldest of all Microsoft’s operating systems is MS-DOS (Microsoft Disk Operating System). MS-DOS is a text-based operating system. Users have to type commands rather than use the more friendly graphical user interfaces (GUI’s) available today. Despite its very basic appearance, MS-DOS is a very powerful operating system. There are many advanced applications and games available for MS-DOS. A version of MS-DOS underpins Windows. Many advanced administration tasks in Windows can only be performed using MS-DOS.

The history of Microsoft Windows dates back to 1985, when Microsoft released Microsoft Windows Version 1.01. Microsoft’s aim was to provide a friendly user-interface known as a GUI (graphical user interface) which allowed for easier navigation of the system features. Windows 1.01 never really caught on.  (The amazing thing about Windows 1.01 is that it fitted on a single floppy disk!). In 1987 Microsoft revamped the operating system and released Windows 2.03.   The GUI was very slightly improved but still looked too similar to Windows 1.01. The operating system again failed to capture a wide audience.

Microsoft made an enormous impression with Windows 3.0 and 3.1. Graphics and functionality were drastically improved. The Windows 3.x family provided multimedia capabilities as well as vastly improved graphics and application support.

Building on the success of Windows 3.x, Microsoft released Microsoft Windows For Workgroups 3.11. This gave Windows the ability to function on a network. It is not uncommon to find companies still using Windows 3.11.

In 1993 Microsoft divided the operating system into two categories; Business and home user. Windows NT (New Technology) was a lot more reliable than Windows 3.x. Windows NT provided advanced network features. On the business front, Windows NT continued to develop with the release of version 3.51. Different versions were provided which offered different functionality. Server provided the higher network functions and Workstation was mainly for the client machines.

In 1995 Windows went through a major revamp and Microsoft Windows 95 was released. This provided greatly improved multimedia and a much more polished user interface. The now familiar desktop and Start Menu appeared. Internet and networking support was built in Although Windows 95 was a home user operating system, it proved to be very popular in schools and businesses.

After the success of Windows 95, Microsoft improved the GUI interface of Windows NT and released Windows NT 4.0. NT4 could be tailored to the size of the business, NT4 Server for small to medium sized businesses and Enterprise Server for larger networks. Microsoft continued to improve the Windows format. Although Microsoft Windows 98 was very similar to Windows 95, it offered a much tidier display and enhanced multimedia support.

Breaking with its own  naming conventions, Microsoft released Windows 2000 (initially called NT 5.0) for the business market. It appeared in 4 models: Professional  -which replaced Workstation, Server, Advanced Server and Datacenter Server catered for differing business requirements.

Although Windows 2000 had a greatly improved user interface, the best of the enhancements appeared on the server side. Active Directory was introduced which allowed much greater control of security and organisation. Improvements to the overall operating system allowed for easier configuration and installation.

One big advantage of Windows 2000 was that operating system settings could be modified easily without the need to restart the machine. Windows 2000 proved to be a very stable operating system that offered enhanced security and ease of administration.

The last incarnation of the Windows 9x family was Windows Millennium Edition (ME). There were many different versions of Windows floating around at this stage that Microsoft decided the next release of Windows would consolidate both the business and home versions. Although Windows ME was visually similar to Windows 2000. Windows ME was based on the Windows 9x line. Windows 9x/ME systems are not as secure and stable as Windows NT and 2000 systems.

Because of the stability of Windows NT/2000, Microsoft decided to end the development of the Windows 9x line, and merge both the consumer and business products. Microsoft Windows XP comes as the Home Edition and Professional, each is based on Windows 2000. Windows 2000 Server has been upgraded to Windows 2003. This appears in four variants: Web Server, Standard Server, Enterprise Server and Datacenter Server, each fulfilling a different business role. Windows XP has a very polished look, but the overall functionality is very similar to Windows 2000.

Other Operating SystemsThe Windows family is the most widely used Operating System. There are other operating systems in the computing world, and some are a lot older than Microsoft Windows. Luckily most operating systems can interoperate with each other. Many of today’s larger networks contain a variety of operating systems.

UNIX

A big advantage of UNIX is that it can be run on nearly every computer hardware platform including Apple Macintosh machines. The UNIX operating system is one of the

oldest and most powerful operating systems. It was developed by Bell Laboratories. There are many variants of UNIX available.

Novell NetWare

Novell NetWare is an advanced network operating system. It has an advanced directory service structure similar to Microsoft’s Active Directory. Fortunately both directory services are interoperable as both directories use the x500 directory service standard.

Linux/FreeBSD

Two of the most popular variations of UNIX come in the form of Linux and FreeBSD. A big advantage of both Linux and FreeBSD is that they are both open-source, that is, any user can contribute to the development of the OS. Versions of both operating systems are completely free.

Linux and FreeBSD can easily take the role of a server or client machine. However, they are considered to be more difficult to master as both utilize the command line rather than a user friendly GUI. There are several different distributions of Linux, but for each the underlying operating system remains the same.

Apple Macintosh machines offer high performance sound and graphics editing and are therefore extremely popular in the design industry. Apple have developed their own operating system, the newest version of which is the Mac OS X, which is based on UNIX.

Mac OS X is a very user friendly operating system and is increasingly popular for home PCs.

Managing Files And FoldersA file is a collection of numbers which have been written to your computer’s hard drive. These numbers can be converted into a picture, a sound, text, or a set of instructions for a program to perform certain actions. A clue to a file’s type is given by its Icon or by its file extension. Folders are containers for anything on a computer including files and

other folders. A path lists the folders that have to be opened to get to the required file. Folders were called directories on older Microsoft systems.

These are some typical file icons. They help the user to identify the file type. There are innumerable file types, some of the common ones are represented here:

1. .bmp – a bitmap image

2. .doc – a Word document

3. .wav – a sound file

4. .ppt  – animated slides

5. .txt – plain text

6. .xls – a spreadsheet

7. .dbf – a database file

8. A shortcut (note the arrow)

9. .exe – an application (a program)

Windows allows you to view information about files in different ways. the icon view – the default used by Windows XP.

To change the icon view, click on View on the menu bar. Select the required view from the available list.

By default if a file type is a  known one, such as a Microsoft Word Document, Windows won’t display its file extension. To view all file extensions click on Tools on the menu bar.

Various options can be configured. e.g. Display compressed files and folders with alternate colours. To display all file extensions, untick the Hide file extensions for known file types box.

File extensions are best left alone. Opening a file with the wrong application can sometimes damage the file. However you may at some stage need to change a file’s extension.

Folders

Each of these is a folder. They may contain files or other folders (called subfolders) or both. There may be many “nestings” of folders within folders.

Files and folders are located on the computer by using a file path. The “James” folder is located inside a folder called “Home”, which is located inside a folder called “es-net”, which is located on the “C:” drive. The file path will be “C:\es-net\Home\James”.

Moving and Copying

To move a file or folder, either right click on its icon OR left click on the Edit  option on the toolbar. Choose cut to move or copy to copy!

At this point the item has been placed onto a clipboard – an area of memory accessible from nearly any application in Windows. Right click (or open Edit in the toolbar) in an open destination folder and choose “Paste” (or use drag and drop) .

When  an attempt is made to move an item between volumes, it is effectively copied, and the original remains.

Creating Files and Folders

This is mercifully easy. Simply right-click on some empty space in any suitable folder or the desktop and choose to create a new object from the choices offered.

Be careful not to alter the file extension, as this can render the file unreadable. File extensions are usually hidden for this reason.

Start MenuThe Start Menu was introduced in Windows 95 and allows for applications to be easily located and launched. As the name implies, The Start menu is the starting point for most tasks in Windows.

The look of the Start menu has changed many times in different versions of Windows but the same idea always applies.

Clicking on START is a recommended way to access frequently used applications:

Clicking on START reveals the Run option which provides a quick way of launching  command-line utilities.

The first few characters of a pathname have been typed and the auto-complete feature uses this to make suggestions based upon recent usage. Clicking on one of these completes the entry. This can be useful to avoid mistyping.

The Start Menu can also be easily configured by simply right-clicking on it and selecting Properties.

Icon sizes can be changed as well as the number of program shortcuts displayed. Select Advanced to view a few in depth options.

Various items can be enabled and disabled by choosing the options shown, e.g. The Control Panel can be disabled from the Start Menu.

To change the Start Menu to the style used in Windows 2000 select Classic Start Menu.

Clicking on Start reveals the older style Start Menu used in pre-Windows XP computers.

Desktop and My DocumentsThe Windows desktop provides a convenient location for storing files and folders. The desktop can contain shortcuts to applications and documents that you access frequently.

This lesson is based on Windows XP, but if you understand this you will understand how the desktop works in all the other versions of Windows too!

This is the Desktop. It is a folder just like any other and it can be manipulated to contain whatever the administrator requires for each user.

The My Documents Folder is the default destination for a user’s work. It can be placed, separately from the desktop, on any server in the network.

In this guise it can still appear to the user as what is known as a local resource!

In another course would-be administrators will move home folders to remote servers. They will also have a good reason for doing so.

Server Roles in Windows Server 2003The term server refers to a machine that is providing a service for other machines, e.g. A computer which shares files on the network would be classed as a file server. For example, A Domain Controller is classed as a server because it is providing a service for the rest of the clients on the network. Windows 2003 can take several different server roles. These are as follows:

File Server

A File Server stores files and folders that are used by other machines on the network. It can hold applications, text documents, or a user’s My Documents Folder.  For security, many shared folders are housed on file servers. A distributed file system is housed on more than one file server for the sake of fault-tolerance and ease of access.

A Windows XP Professional machine may act as a limited File Server.

A Windows Server 2003 Computer can also act as a file server for different operating systems, e.g. Apple Macintosh.

Print ServerA Print Server is a computer that has a printer attached to it and shares the printer for use on the network.

A Windows XP Professional Machine can be a reasonably capable Print Server.

Application ServerBesides being a Domain Controller, Windows Server 2003 can also be a host to many different services e.g. as a Database Server and a Terminal Server.

Some Common Microsoft Servers:

Microsoft Exchange allows you to setup an e-mail server and also allows you setup a messaging and collaboration system for your company’s network.

Microsoft SQL Server enables you to setup up powerful database servers for your company’s network.

Microsoft ISA Server allows you to setup an Internet Gateway/Proxy Server for your company’s network.

These applications require Windows Server 2003. Their integration with Active Directory allows for tighter security and easier administration.

A Database Server holds a database! This is not just a list of information. It is structured, and dynamic. It needs to be managed, updated, extended and secure, while at the same time being accessible to users.  A dedicated server is required for this.

Remote Administration enables an administrator to manage a server from almost any workstation on the network using Terminal Services. Terminal Services lets workstations use powerful applications housed at the server as if they were installed at that workstation.

Web ServersA Web Server hosts and manages websites for the Internet or an intranet. Because of the need to manage heavy and burst-mode traffic while maintaining security, a dedicated server is recommended.

Windows 2003 can function as a web server using the Internet Information Services (IIS) service

Windows XP Professional ships with a limited version of IIS which allows a workstation to host a single website.