Thursday, January 7, 2016

Personal Computer connection methods




Personal Computer Connection Methods
You have now identified the primary components inside the system case. The next thing to do is investigate the means by which those components, and other components, are connected together to form a complete personal computer system. In this topic, you will identify personal computer connection methods.
A personal computer is made up of many different components. To be able to work together effectively to provide users with the computing power they need, these components need to be able to communicate with each other. As personal computers have evolved over the years, dif- ferent connection technologies have been implemented to provide communication among computer components. As a computer technician, identifying the different connection technolo- gies will enable you to install personal computer components quickly and effectively.
Ports Definition:
A port is a hardware interface where you can connect devices to the computer. The port trans- fers electronic signals between the device and the system unit. The port is either an electrically wired socket or plug or a wireless transmission device. Ports can vary by shape, the number and layout of the pins or connectors contained within the port, the signals the port carries, and the port’s location. There are ports for both internal and external devices.

Genders
Ports and the cables that connect to them have genders. For example, if a computer port con- sists of a plug, the matching cable connection will have a socket. The port in this case would be the male connector and the cable would be the female connector. 
 Port Shapes
Ports can have different physical shapes such as male, female, round, rectangular, square, and oblong. There is some standardization of physical properties and functions, though. For example, most computers have a keyboard port (currently round, or telephone type), into which the keyboard is connected.
PS/2 Ports
The round 6-pin ports that many keyboards and mice connect to are called PS/2 ports, after the early IBM Personal System/2 personal computer. To avoid confusion between the identical- looking keyboard and mouse ports, PS/2 ports are often color-coded to match the end of the cable on the device: purple for the keyboard and green for the mouse. Or, there will be a sticker with a picture of a mouse and keyboard near the connectors.
PS/2 ports are also called mini-DIN ports. DIN is the abbreviation for a German standards organization. There is an older, larger DIN port with only 5 pins.
Personal Computer Connections Definition:
A personal computer connection is the collection of hardware components that enables the computer to communicate with internal or external devices. It comprises the ports on both the computer and the device plus a transmission medium, which is either a cable with connectors at each end or a wireless technology. Personal computer connections can be categorized by the technology or standard that was used to develop the device. 

Serial Connections Definition:
A serial connection is a personal computer connection that transfers data one bit at a time over a single wire. Serial connections support two-way communications and are typically used for devices such as fax machines or external modems. Serial ports have either 9-pin (DB-9) or 25-pin (DB-25) male connectors. A serial cable ends with a female connector to plug in to the male connector on the system unit. On system units that have color-coded ports, the serial port is teal-colorer.
Serial Transmissions
In a serial transmission, data is sent and received one bit at a time over a single wire. To accomplish this, the serial communication process:
  1. Disassembles bytes into bits on the sending end of the communication.
  2. Sends the bits across the communication wires.
  3. Reassembles the bits into bytes at the receiving end.
Serial Ports
Serial ports are typically called COM1, COM2, COM3, and COM4, where COM is short for communications port. In modern systems, only one or two serial ports will be present. This port is being phased out in favor of other standards, so you might find some systems with no serial ports at all.
Other Uses for Serial Connections
Serial connections can be used for direct PC-to-PC connections and to connect some mice, printers, and Personal Digital Assistant (PDA) devices.
Parallel Connections Definition:
A parallel connection is a personal computer connection that transfers data eight bits at a time over eight wires and is typically used to connect a printer to a system unit. Parallel connec- tions in older personal computers support only one-way or unidirectional communications. Most computers now have parallel ports that support bidirectional communications. Standard parallel ports have 25-pin female connectors. A parallel cable has a 25-pin male connector to plug into the system unit and a 36-pin male Centronics connector at the other end to attach to the external device. On system units that have color-coded ports, the parallel port is burgundy or dark pink.
Parallel Ports
A PC can have up to three parallel ports, referred to as LPT1, LPT2, and LPT3. LPT is short for line printer.
Other Uses for Parallel Connections
In addition to printers, other devices, such as older scanners, some network adapters, CD-ROM drives, and other types of external drives used to be connected to a system unit by using paral- lel ports. Some devices had piggy-back connections, enabling you to install a second parallel device on a port with the first device.
Universal Serial Bus (USB) Connections Definition:
A USB connection is a personal computer connection that enables you to connect multiple peripherals to a single port with high performance and minimal device configuration. USB connections support two-way communications. Most computers today have one or more USB ports and can, with the use of USB hubs, support up to 127 devices per port. USB cables usu- ally have different connectors at each end. The computer end of the cable ends in a Type A connector. The device end of the cable ends in a Type B connector. The size of the connector varies depending on the device.
USB Standards
USB 2.0 is the current standard. It can communicate at up to 480 Mbps. The original USB 1.1 standard is still commonly found in devices and systems. It can communicate at up to 12 Mbps. A USB 2.0 device connected to a USB 1.1 hub or port will only communicate at USB 1.1 speeds, even though it might be capable of faster speeds. Windows XP will inform you of this when you connect the device.
FireWire Terminology
Apple Computer was the primary vendor to promote the IEEE 1394 standard, and used the FireWire name as a trademark for the IEEE 1394 implementation included in its Macintosh systems. FireWire has since become the common name for all IEEE 1394 devices.
FireWire vs. USB
FireWire predated USB and was faster than the original USB 1.1 standard. USB 2.0, with its increased speed, has largely superseded FireWire. However, although USB 2.0 is faster by the numbers than FireWire, FireWire is actually faster on throughput, making it ideal for video/ audio file transfers and external storage devices. A file transfer of 100 separate documents might be slightly faster on USB than FireWire, but a file transfer of a single 2 GB video file will be much faster in FireWire. Also, while USB provides a device up to 5V power, FireWire provides up to 12V power on the wire.

Small Computer Systems Interface (SCSI) Connections
Definition:
SCSI is an older connection standard, typically used for storage devices such as tape and hard drives, that remains in use due to its reliability and high speed. A SCSI adapter has a port for external devices and a connection for internal devices. SCSI devices themselves can have mul- tiple ports, enabling you to connect several devices in a chain to one SCSI adapter. Each device in the chain requires a unique ID, which you configure by using switches or jumpers. SCSI cables have 50-pin, 68-pin, or 80-pin connectors depending upon the type of SCSI in use.
Parallel ATA (PATA) Connections
Definition:
A PATA connection is a drive connection standard that provides a parallel data channel from the drive controller to the disk drives. Originally called IDE, EIDE, or ATA, PATA connections are used to connect internal hard drives, optical drives, and tape drives to the system board. On the system board, two sockets provide connections for up to two drives per socket. PATA cables are ribbon cables with 40 or 80 wires and 40-pin connectors.
ATA, IDE, and EIDE
IDE (Integrated Drive Electronics) and EIDE (Enhanced IDE) are alternative names for the ATA (Advanced Technology Attachment) standards that are now referred to as PATA. (After Serial ATA drives became popular, the PATA term was coined to refer to the parallel drives.) There have been several versions of the ATA standard, with successive versions providing sup- port for different types of devices, or providing performance enhancements such as higher data rates. For example, ATAPI (Advanced Technology Attachment Packet Interface) provides sup- port for tape drives and CD-ROM drives, while ATA-7 supports data rates up to 133 MB/sec.
Master and Slave Designations
PATA drives are configured in a master/slave hierarchy, usually by setting jumpers. Each PATA channel can support one or two devices. Because each PATA device contains its own integrated controller, you need to have some way of differentiating between the two devices. This is done by giving each device a designation as either master or slave, or by using the Cable Select feature to assign master and slave designations, and then having the controller address com- mands and data to either one or the other.

Serial ATA (SATA) Connections Definition:
A SATA connection is a drive connection standard that enhances PATA by providing a serial data channel between the drive controller and the disk drives. SATA transfer speeds are much higher than PATA for the same drive technologies. SATA’s physical configuration is also easier because the SATA serial cables are much smaller, thinner, and more flexible than traditional PATA ribbon cables. SATA connectors have four pins.


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