Datasheet

points, instead advising users to attach old-style devices to the multipurpose
USB port or to purchase a special cable that converts a USB signal to a parallel
or standard serial connection.
You may find these legacy ports on a laptop:
 Parallel port: Direct connection to older printers and certain other devices
that require this sort of cabling in which 16 bits of information march along
next to each other in separate wires instead of one behind each other in a
serial connection. (Parallel used to be faster than serial, but modern tech-
nologies have reversed that trend.)
 Serial port: The original form of computer communication, used mostly for
early telephone modems and some printers. Now completely replaced by
USB circuitry; if your laptop does not offer this port and you need to emu-
late an older, slower form of communication, you can purchase a converter
than uses the USB port.
 Keyboard/mouse port: The small, circular port used by desktop machines
to connect keyboards and mice was also available on some older laptops.
There may have been one port for each device, or a single port able to
work with either device. Why would you want an external mouse or key-
board when your laptop comes equipped with one of each already? First of
all, an external device is usually larger and easier to use. Secondly, you can
choose to install a specialty pointing device or keyboard — a board with
European accent characters, the slightly different arrangement of keys you
find in some parts of the world, or a more precise trackball or optical
mouse instead of the pressure-sensitive touchpad or stick used by most
laptops. And finally, an external port allows you, in a pinch, to work around
the failure of your laptop’s keyboard or pointing device.
 Docking station/expansion port: Older machines often were designed with
a large connector at the rear that extended the computer’s internal bus to
an external docking station on a desktop. This was intended to allow addi-
tion of more ports, an external mouse or keyboard, external hard disk
drives, and other devices. The docking station connector was usually a
proprietary design that worked only with a particular manufacturer’s com-
bination of laptop and expansion module. Docking stations were not much
used by most laptop owners, and have been replaced by the multifunction
USB port and by WiFi and wired networks.
Delving into Basic Software
Okay, here’s a metaphysical question: Is a computer a collection of hardware
that exists to run software, or is software a set of instructions that is created to
make use of the hardware?
8 Part 1: The Laptop Computer
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