Universal Serial Bus (USB) (Understanding Expansion Buses)

Universal Serial Bus (USB)

Universal serial bus (USB) is an external peripheral bus standard designed to bring plug and play capability for attaching peripherals externally to the PC. The bus supports up to 127 devices simultaneously. 

This Icon/ symbol is use to identify USB cables, connectors, hubs, peripherals.



USB conforms to Intel’s plug and play (PnP) specification, including “Hot” plugging, which means that devices can be plugged in dynamically without powering down or rebooting the system. Simply plug the device, and the USB controller in the PC detects the device and automatically allocates the required resources and drivers. USB supports following data transfer rate, depending on the amount of bus bandwidth a peripheral device requires.

§ 1.5 mega bits per second (Mbps) for devices, such as a mouse or keyboard, that do not required large amount of bandwidth.

§ 12 Mbps transfer rate for high-bandwidth devices such as modem, speakers, Scanners etc.

USB sends signals over simple four-wires the physically two series are specified for USB.

§ Series “A” connector is designed for devices in which the cable remains permanently attached, such as hubs, keyboard, and mice. The USB ports on most motherboards are normally a series “A” connector.

§ Series “B” connector are designed for devices that required data cable, such as printers, scanners, modems and telephones. The physical USB plugs are small and unlike a typical serial or parallel cable connector.

Note: Maximum cable length between two USB full-speed (12Mb/sec) devices is 5-Meters; while for lower speed (1.5Mbp/sec) devices are 3meters.

Types of USB Sockets Type A and Type B

Introduction To MotherBoard

Introduction of Motherboard:-

Motherboard is a circuit board also called main board. All components of a computer are connected together using motherboard. (It is called mother board because it connect all components together, like a mother). Components on a motherboard are connected together using a set of wires called buses. All important components of computer (like processors, RAMs, Cards) are connected directly to motherboard while other components are connected using ports available on a motherboard. Computer motherboard has Sockets, Slots, Bays and Ports to connect different components.

Socket:-

A socket is usually a square shape connector. It connects chips in in it. Today Microprocessors are mostly in form of a chip and are inserted in Sockets.

Slots:-

Slots are usually rectangular connectors. There are many types of slots present on computer motherboard. slots are used to ad extra features to motherboard. Slots are used to insert cards. Following slots are available on motherboards. Slots are also called edge connectors.
RAM Slots
PCI Slots
AGP Slots
ISA Slots
EISA Slots

Bays:-

Bays are used to connect drives (CD-ROM, Floppy, Hard Disk, Tape etc.) to computer motherboard.  Most commonly used bay is ATA (Advance Technology Attachments). It is available in PATA (Parallel Advance Technology Attachments) and SATA (Serial Advance Technology Attachments). Modern motherboards mostly coming with only SATA bays as it is faster then PATA.

Ports:-

Ports are mostly available on the back panel of Motherboard. These Ports are used to connect devices to computers. A variety of ports are available now a days. PS2 ports are used to connect Keyboard and Mouse, Serial Ports are used to connect many devices including mouse, joysticks etc. LPT port is used to connect printers. Sound ports are used to connect audio jacks. VGA Port is used to connect monitor or LCD. DVI port is also available for Monitor and LCDs. HDMI port is avail able for Video interfaces.

The most widely used ports today are USB Ports (Universal Serial Bus). almost each and every devices are available in USB connection. Thats why Modern motherboards come with very fewer slots. USB ports are HOT PLUG&Play Ports.

The Motherboard Introduction (Images)

Computer Case Front

Computer Case Back

Motherboard Components

Motherboard Back Panel