Connections

the Physical Computer
a Training Module of the
Assistive Technology Division
Mississippi Department of Rehabilitation Services

Connections

Keyboard	Mouse	Video	Serial	Parallel	Joystick
Modem	Network	USB	Firewire	Sound	Power

Typical connections on the PC
	The motherboard has input/output connections that fit through the case and provide access to the motherboard via the rear of the computer.These are diagramatic representations of typical connectors found on motherboards or on cards.
Integrated Motherboard Connections View as it appears when looking at the back of the computer case. 1. PS/2 Keyboard 6-pin Female mini DIN connector for attaching a PS/2 keyboard. 2. PS/2 Mouse 6-pin Female mini DIN connector for attaching a PS/2 mouse. 3. USB ports UHCI Universal Serial Bus root hub for connecting devices such as a keyboard, mouse, scanner, digital camera, or other USB-compatible devices. 4. LAN or Modem (Optional) A LAN (RJ-45) or Modem (RJ-11) jack for connection to a Local Area Network or phone line. 5. COM A 9-pin Male mini DIN serial connector for attaching a mouse or other serial device. 6. VGA 15-pin Female DB connector for attaching to a (S)VGA monitor. 7. Parallel Port LPT-1 25-pin Female Centronics connector supporting both EPP and ECP modes for connection to a printer or other parallel device. 8. Line-Out 1/8" stereo audio connection for attaching speakers or headphones. 9. Line-In 1/8" stereo audio connection for attaching an external CD player, tape deck, or other audio device. 10. Microphone 1/8" stereo audio connection for attaching a microphone. 11. MIDI or Joystick 15-pin Female DB connector for attaching a joystick or game pad. It can also be used to connect MIDI devices.

Keyboard
The keyboard is typically connected with a PS-2 mini-DIN connector. The keyboard is the bottom connector, the mouse is the top.
Modern keyboards are frequently USB connected. They sometimes have hubs or multiple USB ports built into them so that you can add other USB devices easily.
Wireless keyboards are becoming increasing popular. The wireless receiver usually connects to the computer via USB.
Legacy keyboards would have been connected via old style DIN connectors. They are larger than the PS-2 mini-DIN	DIN on top, mini-DIN on bottom
Occasionally you might see a serial keyboard. This would connect via the seria port...using a DB-9 connector.

Mouse
The mouse is typically connected with a PS-2 mini-DIN connector. The mouse is the top connector, the keyboard is the bottom.
Modern mouses are frequently USB connected. The adapter converts the USB A end to a PS-2 mini-DIN.
A wireless mouse is becoming increasing popular. The wireless receiver usually connects to the computer via USB.
A legacy mouse would have been connected via a serial port.

Video
The typical VGA video uses a DB-15 (with three rows of pins). The connector is frequently blue.
Do not confuse this with the DB-15 (with two rows of pins) found on sound cards. This connector is for use with joysticks.
DVI is the latest development in video connections. This is the male DVI connector from the monitor.
The DVI female input connection on the video card would look like this.
A modern video card is loaded with on-board dedicated RAM, chipsets, GPU, fan, etc.
Some video cards provide dual monitor capability

Serial Port
The serial port (RS-232) is a DB-9 connector. This is a legacy connector. It is rarely used on modern peripherals. This port has been replaced by the USB port.
A serial mouse was the most common serial connection.
Occasionally you might see a serial keyboard. This would connect via the seria port...using a DB-9 connector.
Adapters that convert a DB-9 serial connector to a USB connector are available.

Parallel Port (Printer or LPT port)
The parallel port is a DB-25 connector. This port is also referred to as a printer port or LPT port. It is rarely used on any modern peripherals other that printers. This port has been replaced by the USB port.
The other end of the printer cable typically was a Centronics connector. This is a 36 pin Centronics printer side connector.

Joystick
The joystick port is a DB-15 connector. The 15 pins occur in two rows. This port is typically found on sound cards.
Do not confuse this connector with the DB-15 video connector. The video port has 15 pins configured in three rows.

Modem
Modems can be internal PCI cards, external units, or on-board the motherboard. There are two RJ-11 connections. One receives the line in from the telephone company. The other allows you to connect a phone to the modem.
	Always look for the side by side pair of RJ-11 jacks to avoid confusion with a Network Card (NIC) which has the slightly larger RJ-45 jack.
RJ-11: Short for Registered Jack-11, a four- or six-wire connector used primarily to connect telephone equipment in the United States. RJ-11 connectors are also used to connect some types of local-area networks (LANs), although RJ-45 connectors are more common.

Network
The modern Network Interface Card (NIC) is typically a 10/100 Ethernet card. It utilizes the RJ-45 connector. The unit will typically have a light that indicates network connectivity.
The RJ-45 connector is larger that the typical telephone jack (the RJ-11).

USB
Short for Universal Serial Bus, an external bus standard that supports data transfer rates of 12 Mbps. A single USB port can be used to connect up to 127 peripheral devices, such as mice, modems, and keyboards. USB also supports Plug-and-Play installation and hot plugging. Starting in 1996, a few computer manufacturers started including USB support in their new machines. It wasn't until the release of the best-selling iMac in 1998 that USB became widespread. It is expected to completely replace serial and parallel ports.	this USB cable (square B end) sends data and power to a device
USB 1.1 is the standard that developed in regards to the 1996 device. One of the great things about USB is that the connections allows the transfer of data and also provides power. USB 2.0 (Hi-Speed USB), is an external bus that supports data rates up to 480Mbps. USB 2.0 is an extension of USB 1.1. USB 2.0 is fully compatible with USB 1.1 and uses the same cables and connectors. Hewlett-Packard, Intel, Lucent, Microsoft, NEC and Philips jointly led the initiative to develop a higher data transfer rate than the 1.1 specification to meet the bandwidth demands of developing technologies. The USB 2.0 specification was released in April 2000.
For great info about USB 2.0 see: http://www.intel.com/technology/usb/faq.htm	If you mix USB 1.1 and USB 2.0 (devices, ports, hubs, cables, etc) the system will work at the speed of the slowest component.
The USB symbol, is a marker for spotting the USB port. The port itself on the computer looks like these connectors.	You can get USB hub that will take one USB port and convert it to a number of USB ports. Many will offer other port connectors as well.
the USB 1.1 or 2.0 cable are identical	USB ports on the computer are usuall ganged together
the USB A rectangular end attaches to the computer	the USB B square end attaches to the device

FireWire

Sound
A sound card or an on the motherboard sound connection typically has at least 3 connections. These are for 1/8" jacks. The inputs are usually: line in, mic, and speakers. The speaker inputs are frequently green.
A sound card may have many different configurations. Many have a joystick connection that is a DB-15 with 2 rows of pins. State of the art sound cards will have a variety of high level audiophile quality connections including surround sound with up to 8.1 speaker systems.

Power
The power supply takes in 110 volts AC and converts this to a variety of DV voltages (±3.3 v DC, ±5 v DC and ±12 v DC)
The typical 110 v AC connector on the back of the computer is a recessed 3 prong male. Often the power supply will have an alternate recessed 3 receptacle female.	For more information see Power Supply

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