Computer hardware by heera computer

04/11/23 Prepared By: Fateh Singh1

Computer Hardware Components


Computer Hardware components


Computer Hardware components

MotherboardCPUKeyboardMouse RAMMonitor Floppy drive CD-ROM driveHard disk driveDVD Drives


Central Processing Unit

The microprocessor consists of three sections:

1.Arithmetic Logic Unit2.Registers

3.Control Unit


Keyboard

The keys on computer keyboards are often classified as follows:

alphanumeric keys -- letters and numbers punctuation keys -- comma, period,

semicolon, and so on. special keys -- function keys, control

keys, arrow keys, Caps Lock key, and so on


Mouse

A device that controls the movement of the cursor or pointer on a display screen. A mouse is a small object you can roll along a hard, flat surface.


Mouse

There are three basic types of mouse

mechanical: Has a rubber or metal ball on its underside that can roll in all directions

optomechanical: Same as a mechanical mouse, but uses optical sensors to detect motion of the ball.

optical: Uses a laser to detect the mouse's movement


RAM

RAM, or Random-Access-Memory, is a type of memory that accesses faster than main memory (like a hard drive), but that only stores data while the computer is turned on. It is normally used to store the program that your computer is currently running, and any data that program needs.

RAM is divided into small blocks of data, each of which can be accessed by

a unique number, called an address.


Monitor

The computer screen is used for outputting information in an understandable format.


Floppy drive

Storage Devices -- "How it saves data and programs“- - Hard disk drives are an internal,higher capacity drive which also stores theoperating system which runs when you poweron the computer.-

"Floppy" disk drives allow you to savework on small disks and take the data withyou.


Diskettes (Floppy Disks) Speed:

Very slow!

Capacity:

Normally 1.44 Mbytes. Cost:

Very cheap.


Hard Disks

Hard Disks Speed: fast! The speed of a hard disk is often quoted as "average access time" speed, measured in milliseconds. The smaller this number the faster the disk. Capacity: Enormous! Often 40/80 Gigabytes. A Gigabyte is equivalent to 1024 Megabytes. Cost: Hard disks costs are falling rapidly and normally represent the cheapest way of storing data.


CD-ROM drive

They are disc drives which read Compact Discs (CDs). They are transportable and can be used to perform various tasks such as reading data from the computer and listening to audio.

Data is written on a CD by burning pits into the disc to produce non-reflective areas.


DVD Drives

Computer DVD drives can be used to watch DVD video, play audio CDs and store information on DVDs and CDs. DVD drives are now being installed in new computers instead of CD drives.

Computer DVD drives are able to read data stored on CD-ROMS and DVDs and can play both video and audio DVDs. CD-ROM drives cannot read DVDs.


MOTHERBOARD

The motherboard contains the connectors for attaching additional boards, such as the CPU, BIOS, memory, mass storage interfaces, serial and parallel ports, expansion slots and all the controllers that are required to control standard peripheral devices such as the display screen, keyboard, and hard drive.


INTRODUCTION

THERE ARE VARIOUS PORTS AND SLOTS ARE GIVEN ALONG WITH LABELED PHOTOGRAPH


Universal Serial Bus

Universal Serial Bus (USB) is a serial bus standard to interface devices. USB was designed to allow many peripherals to be connected using a single standardized interface socket and to improve the plug-and-play capabilities by allowing devices to be connected and disconnected without rebooting the computer (hot swapping).


P.C.I PORTS OR SLOTS

16 serial ports available from one PCI slot

Data transfer rate up to 115.2 Kbps asynchronous, full duplex, simultaneously on all ports

Full modem support on all ports 128 bytes data buffer on each

channel On board hardware and software

flow control on all ports Driver support for SPARC, Solaris,

X86 Solaris, Window 98-2000, and Linux operating systems


MEMORY CARD SLOT

Memory card slots are used primarily to add memory to a phone, in the form of a memory card. Extra memory can be used to store and transfer photos, videos, music, computer files, or backups of phone data such as the phone book and calendar.

There are several different types of cards. Each has a different shape and size, but cards from a phone can also be used with other devices which use the same type of card. Such devices might include handhelds, digital cameras, and MP3 music players.


PS/2 connector

The PS/2 connector is used for connecting some keyboards and mice to a PC compatible computer system. Its name comes from the IBM Personal System/2 series of personal computers, with which it was introduced in 1987. The PS/2 mouse connector generally replaced the older DE-9 RS-232 "serial mouse" connector, while the keyboard connector replaced the larger 5-pin DIN used in the IBM PC/AT design. The keyboard and mouse interfaces are electrically similar with the main difference being that open collector outputs are required on both ends of the keyboard interface to allow bidirectional communication. If a PS/2 mouse is connected to a PS/2 keyboard port (or if a PS/2 keyboard is connected to a PS/2 mouse port), the mouse (or keyboard) may not be recognized by the computer depending on configuration.


AUDIO, MIC & LINE JACK

The JACK Audio Connection Kit or JACK is a sound server daemon that provides low latency connections between so-called jackified applications, for both audio and MIDI data. It is created by Paul Davis and others. The server is licensed under the GNU GPL, while the library is licensed under the GNU LGPL.


PARALLEL PORTS

A parallel port is a type of interface found on computers (personal and otherwise) for connecting various peripherals. It is also known as a printer port or Centronics port . The IEEE 1284 standard defines the bi-directional version of the port.


ETHERNET PORTS

Ethernet is the most common type of connection computers use in a local area network (LAN). An Ethernet port looks much like a regular phone jack, but it is slightly wider. This port can be used to connect your computer to another computer, a local network, or an external DSL or cable modem


VGA PORT

Connect a PC to a monitor. This is a venerable but now completely standard monitor interface. The original VGA monitors could do no more than 640x480. During the mid 1990's, more advanced monitors were called "SVGA" (for Super). Since all monitors can display more than 640x480 today, the two terms are now interchangable.

This HDD-15 port seems to have evolved facing upside-down on most machines.


HUBS

A network hub or concentrator is a device for connecting multiple twisted pair or fiber optic Ethernet devices together, making them act as a single network segment. Hubs work at the physical layer (layer 1) of the OSI model, and the term layer 1 switch is often used interchangeably with hub. The device is thus a form of multiport repeater. Network 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 network switches has largely rendered hubs obsolete but they are still seen in older installations and more specialized applications.


Technical Information

A hubbed Ethernet network behaves like a shared-medium, that is, only one device can successfully transmit at a time and each host remains responsible for collision detection and retransmission. With 10BASE-T and 100BASE-T links (which generally account for most or all of the ports on a hub) there are separate pairs for transmit and receive but they are used in half duplex mode in which they still effectively behave like shared medium links.

A network hub or repeater, is a fairly unsophisticated broadcast device. Hubs do not manage any of the traffic that comes through them, and any packet entering any port is broadcast out on every other port (other than the port of entry). Since every packet is being sent out through every other port, packet collisions result--which greatly impedes the smooth flow of traffic.


The need for hosts to be able to detect collisions limits the number of hubs and the total size of the network. For 10 Mbit/s networks, up to 5 segments (4 hubs) are allowed between any two end stations. For 100 Mbit/s networks, the limit is reduced to 3 segments (2 hubs) between any two end stations, and even that is only allowed if the hubs are of the low delay variety. Some hubs have special (and generally manufacturer specific) stack ports allowing them to be combined in a way that allows more hubs than simple chaining through Ethernet cables, but even so a large Fast Ethernet network is likely to require switches to avoid the chaining limits of hubs.

Most hubs detect typical problems, such as excessive collisions on individual ports, and partition the port, disconnecting it from the shared medium. Thus, hub-based Ethernet is generally more robust than coaxial cable-based Ethernet, where a misbehaving device can disable the entire segment. Even if not partitioned automatically, a hub makes troubleshooting easier because status lights can indicate the possible problem source or, as a last resort, devices can be disconnected from a hub one at a time much more easily than a coaxial cable. They also remove the need to troubleshoot faults on a huge cable with multiple taps.


Dual speed hubs

In their early days, Fast Ethernet switches were relatively expensive . However, hubs suffered from the problem that as simple repeaters they could only support a single speed. Whilst normal PCs with expansion slots could be easily upgraded to Fast Ethernet with a new network card, computers with less common expansion mechanisms, or no expansion bus at all, and other equipment, such as printers, could be expensive or impossible to upgrade. Therefore, a compromise between a hub and a switch appeared known as a "dual speed hub".

Such a device essentially consisted of two hubs (one of each speed) and a two port bridge between them. Devices were connected to the appropriate hub automatically based on their speed and the bridge handled inter-speed traffic. Since the bridge only had two ports and only one of those needed to be 100Mbit/s it could be much simpler and cheaper than a full fast Ethernet switch. Such devices have been rendered obsolete by the decreasing cost of fast Ethernet switches


Connectors

An connector is a conductive device for joining electrical circuits together. The connection may be temporary, as for portable equipment, or may require a tool for assembly and removal, or may be a permanent electrical joint between two wires or devices. There are hundreds of types of electrical connectors. In computing, an electrical connector can also be known as a physical interface. Connectors may join two lengths of flexible wire or cable, or may connect a wire or cable to an electrical terminal.


Commonly used connectors

1. 8P8C connector 8P8C is short for "eight positions,

eight conductors", and so an 8P8C modular connector (plug or jack) is a modular connector with eight positions, all containing conductors. The 8P8C modular plugs and jacks look very similar to the plugs and jacks used for FCC's registered jack RJ45 variants, although the true and extremely uncommon RJ45 is not really compatible with 8P8C modular connectors. It neither uses all eight conductors (but only two of them for wires plus two for shorting a programming resistor) nor does it fit into 8P8C because the true RJ45 is "keyed". The connector is probably most famous for its use in Ethernet and widely used on CAT5 cables.

8P8C connector


2.D-subminiature connectors

A male DE-9 plug. The D-subminiature electrical connector is

commonly used for the RS 232 serial port on modems and IBM compatible computers. The D-subminiature connector is used in many different applications, for computers, telecommunications, and test and measurement instruments. A few examples are monitors the and joysticks and mice, and game consoles such as Atari, Sega and Amiga.


3. USB connectors A male USB series A plug The Universal Serial Bus is a serial bus

standard to interface devices, founded in 1996. It is currently widely used among PCs, Apple Macintosh and many other devices. There are several types of USB connectors, and some have been added as the specification has progressed. The most commonly used is the (male) series "A" plug on peripherals, when the cable is fixed to the peripheral. If there is no cable fixed to the peripheral, the peripheral always needs to have a USB "B" socket. In this case a USB "A" plug to a USB "B" plug cable would be needed. USB "A" sockets are always used on the host PC and the USB "B" sockets on the peripherals. It is a 4-pin connector, surrounded by a shield. There are several other connectors in use, the mini-A, mini- B and mini-AB plug and socket (added in the On-The-Go Supplement to the USB 2.0 Specification).


4. Power connectors Power connectors often include a safety ground connection as well as the power

conductors. In larger sizes, these connectors must also safely contain any arc produced when an energized circuit is disconnected or may require interlocking to prevent opening a live circuit.

5.Radio frequency connectors Connectors used at radio frequencies must not change the impedance of the

transmission line of which they are part, otherwise reflections and losses will result. A radio-frequency connector must not allow external signals into the circuit, and must prevent leakage of energy out of the circuit. At lower radio frequencies simple connectors can be used with success, but as the radio frequency increases (so that the dimensions of the connector are getting close to a small fraction of one wavelength, connector design becomes increasingly critical. At UHF and above, silver-plating of connectors is common to reduce losses.

For Wi-Fi antennae the R-TNC connectors are used. A BNC connector is common for radio and test equipment used up to about 1 GHz.

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Computer hardware by heera computer