Microsoft Office Tutorials and References
In Depth Information
Data Communications
signal, or optical fibers. The computer 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.
Data Bus
As noted earlier, peripherals are devices that can be added to a computer system to
enhance its usefulness. Starting at the microprocessor, and passing through a continuous
channel, the data travels out to the appropriate device. From an input device back to the
microprocessor, the path is reversed. This communication between the microprocessor,
RAM, and the peripherals is called the data bus .
An external peripheral device must have a corresponding port and cable that connect
it to the back of 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 slots or expansion slots . Figure 23 shows the data path that con-
nects a printer to a computer. An internal peripheral device such as a hard disk drive may
plug directly into the motherboard, or it may have an attached controller card. The trans-
mission protocol is handled by a device driver , or simply driver , which is a computer pro-
gram that can establish communication because it contains information about the
characteristics of your computer and of the device.
Components for connecting a printer to a computer
Figure 23
controller card
motherboard
cable
port
printer port
expansion slots
Rear view of system unit
Rear view of printer
Personal computers can have several types of ports, including USB, parallel, serial,
SCSI, and MIDI. Figure 24 diagrams how the ports on a desktop personal computer
might appear.
 
 
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