Chapter 7 Digital Prepress 129
software have made this platform a strong competitor
to the Macintosh® for DTP applications.
UNIX®
UNIX® is a computer operating system that was
developed in 1969 by a group of AT&T employees at
Bell Labs. During the late 1970s and early 1980s, the
infl uence of the UNIX® system within academic circles
led to large-scale adoption of the operating system by
commercial startups, the most notable of which is Sun
Microsystems, Inc. The Macintosh® OS X operating
system is a UNIX®-based operating system.
Today, UNIX®-like operating systems are
commonly found, in addition to certifi ed UNIX®
systems. Linux® is a UNIX®-like computer operating
system and one of the most common open-source
operating systems. An open-source operating system
is a computer system that has had part of the source
code released so third parties can develop programs.
Being a free, open-source system, the Linux® source
code can be modifi ed, used, and redistributed by
anyone. It is used as an operating system for a wide
variety of computer hardware, including desktop
computers like the Macintosh® OS X, supercomputers,
video game systems, and embedded devices, such
as mobile phones and routers.
Memory Types
In addition to having a computer system capable
of running programs, there must be some means
of storing and transmitting data. Every computer
system is equipped with a certain amount of physical
memory, usually referred to as random-access
memory (RAM). RAM is the short-term memory
the computer uses to store information in process.
Systems can be updated and memory capabilities
can be increased to enhance computing effi ciency.
Because most page composition fi les are very
large, there are many types of storage devices available
that accommodate large fi les. Storage devices vary in
terms of capacity, physical size, access capabilities,
speed, reusability, and integrity. Storage capacity is
measured in kilobytes (1024 bytes), megabytes (1024
kilobytes), and gigabytes (1024 megabytes).
A number of different types of devices have been
developed to store and reuse digital fi les. Some of
these devices use disks that contain magnetic tracks
to hold the encoded data, while others laser write
data onto specially coated discs. With the exception
of the hard drive, storage devices make fi les portable,
which allows a copy of the data to be loaded onto
another computer.
Hard Drive
Both external and internal hard drives are common
today, Figure 7-4. A hard drive contains one or more
rigid, non-removable aluminum disks coated with a
magnetic material. When the computer is operating,
the drive motor spins the disk and a read/write head
moves over the disk surface, which contains densely
packed magnetic tracks. The head is used to write,
or magnetize, information to portions of the tracks as
they spin past the head. The head can also read, or
play back, previously stored information.
The amount of information that can be stored on
a hard drive has increased steadily from fewer than
10 megabytes to capacities measured in gigabytes.
Almost unlimited storage capacity is available with
a confi guration known as a RAID (Redundant Array
of Independent Disks), which connects a number of
high-capacity hard drives together, Figure 7-5. The
connected drives act like a single, huge hard drive,
which is an advantage when managing extremely
large fi les involving graphics and text. Virtually all
digital prepress systems have an internal hard drive.
The single most critical occurrence for a hard
drive is when it becomes inoperable, or crashes.
The adage of “It isn’t if your hard drive is going to
crash, it’s when your hard drive is going to crash”
should be taken very seriously. Optimizing the drive
for operational effi ciency and regularly backing
up the data should be part of standard operating
procedures.
platform: The computer system that is used to operate
software. The platform defi nes the standard around which a
system can be developed.
hardware: A computer and its associated devices.
software: Computer programs that initiate and accomplish
various computer-based tasks.
cross-platform: Describes applications, formats, or
devices that work on multiple computer operating system
platforms.
graphical user interface (GUI): A method of representing
computer operations and programs on the screen with icons
that can be selected with a mouse to perform activities.
random-access memory (RAM): Type of short-term
computer memory that stores information in process.
megabyte: One million bytes; usually abbreviated MB.
gigabyte: One billion bytes, abbreviated GB.
RAID: Redundant Array of Independent Disks. A hard drive
confi guration that connects a number of high-capacity hard
disk drives together.