128 Graphic Communications
The American Standard Code for Information
Interchange (ASCII) provides a way to digitally store
and process letters, numbers, punctuation marks,
and symbols. When the letter C is pressed on a
keyboard, for example, it is converted to a specifi c
combination of 1s and 0s. Different combinations are
assigned for the capital and lowercase forms of each
letter. Once in digital form, the information can be
processed by the computer’s circuits and stored as
digital or magnetic charges.
Regardless of size or complexity, a computer
system has three major functions: input, processing,
and output, Figure 7-2. Computer systems also have
some means of storing information, either within
the system, in a portable form, or both. There are a
number of different methods and devices used for
input, storage, and output. They are described in the
following sections.
Computer Platforms
The platform of a digital prepress system is the
computer system hardware used to operate various
programs. Computer platforms include the elements
necessary to create, assemble, and output data
in the fi nished pages, Figure 7-3. Major computer
platforms are PC (based on the Microsoft® Windows®
operating system and the Intel® chip architecture),
Apple® Macintosh®, and UNIX®. Once the platform
is defi ned, software developers design and install
corresponding software applications. Software
is a computer program that initiates a specifi c
function of the computer. Types of software include
word processing, page composition, and graphics
programs.
Some fi le formats and devices are cross-
platform, which means they can operate on or be
used with different platforms. For example, a cross-
platform word processing program allows users
to create and modify documents using different
operating systems, if necessary. Ideally, all computer
systems involved in creating and producing a
document or project would use the same operating
platform. When this is not possible, using cross-
platform applications and devices reduces errors
due to fi le conversion and makes the entire process
more effi cient.
Macintosh®
The Macintosh® computer was introduced in 1984
and quickly became popular because of its ease of
use and ability to generate high-quality graphic
images. The Macintosh® system was designed
around the concept of a graphical user interface
(GUI), which allowed for easy-to-understand, on-
screen graphic representations of computing tasks.
At that time, competing platforms were based on the
more diffi cult method of typing commands to perform
tasks. This platform was central to the development
of Desktop Publishing (DTP) Systems and continues
to play a major role.
Personal Computers (PCs)
The PC is the platform most often used in
business environments. In the early 1990s, the
original command-based operating system for PCs
was replaced by Microsoft® Windows®, which was a
GUI designed to give the PC the same ease of use
as the Macintosh®. The introduction of versatile word
processing programs, sophisticated illustration and
graphics software, and powerful page composition
Input
Processing
Output
Figure 7-2. This computer system confi guration
illustrates the three main functions of input (keyboard
and mouse), processing (CPU), and output (monitor
and printer).
Figure 7-3. Desktop publishing allows graphic
designers to create and edit both text and art.