Microsoft Office Tutorials and References
In Depth Information
Data Communications
Like input devices, output devices can be connected to a computer using cables or a
wireless connection.
The computer advertised in the Visual Overview includes a sound card; it would be
hard to buy a computer today without one. The speakers are built into the monitor. It also
includes a color inkjet printer, although it is not shown. Elizabeth and Scott might want
to consider upgrading to a color laser printer that will enable them to print high-quality
correspondence, advertisements, and brochures.
Data Communications
The transmission of text, numeric, voice, or video data from one computer to another
or to a peripheral device is called data communications . This broad-based defi nition
encompasses many critical business activities, from sending a letter to the printer upstairs
to sending an email message to the company employees around the globe.
The four essential components of data communications are a sender, a receiver, a
channel, and a protocol. The computer that originates the message is the sender . The
message is sent over some type of channel , such as telephone or coaxial cable, a
microwave signal, or optical fi bers. The computer or device at the message’s destination is
called the receiver . The rules that establish an orderly transfer of data between the sender
and the receiver are called protocols . Communication software and hardware establish
these protocols at the beginning of the transmission, and both computers follow them
strictly to guarantee an accurate transfer of data. The transmission protocol is handled by
a device driver , or driver , which is a computer program that can establish
communication because it contains information about the characteristics of your computer and of
the device.
Data Bus
Starting at the microprocessor, and passing through a continuous channel, data travels to
the appropriate peripheral device. From an input device back to the microprocessor, the
path is reversed. This path between the microprocessor, RAM, and peripherals is called
the data bus .
An external peripheral device must have a corresponding expansion port and cable
that connect it to the computer. Inside the computer, each port connects to a controller
card , sometimes called an expansion or interface card . These cards, which provide an
electrical connection to a variety of peripheral devices, plug into electrical connectors
on the motherboard called expansion slots or slots . An internal peripheral device such as
a hard disk drive might plug directly into the motherboard, or it might have an attached
controller card.
Personal computers can have several types of ports. Figure 20 shows a desktop PC
with its ports identifi ed.
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