Information Technology Reference
In-Depth Information
software, more of your computer's memory will be used for
the same software.
2.
New software, unplanned at the purchase time of your com
puter but desired as your needs or experience changes, may
require significant amounts of main memory.
3.
Software may run on machines with only moderate amounts
of memory, but performance may be sluggish. If you have
only the minimum amount of memory, you may be sacrific
ing performance.
The first two of these reasons have the common theme that
memory demands of application software have expanded dramati
cally over the years. Modest applications that once ran in only a few
thousand bytes of memory (e.g., a few kilobytes) now have new fea
tures and graphical capabilities that may require millions of bytes of
memory (e.g., megabytes). Of course, a potential computer owner
may believe that she or he will not need to purchase new software
or new versions of old software, so there is no need to plan for ad
ditional capacity. In practice, however, such intentions often are im
practical. New versions of software may correct errors that were un
covered in previous versions. Even if the original software has
adequate capability, reliability, and performance, the owner may
want to share documents or application files with others (e.g., pro
fessional colleagues, friends, or family) and receive materials from
them. If those people have new versions of software, old versions
may be unable to read or otherwise handle what the new versions
produce. Compatibility of versions can be a problem, forcing adop
tion of new versions to allow sharing—even when the current soft
ware seems to work fine.
To give some idea about how the size of software packages in
crease, let's consider an example: the Microsoft operating system.
Originally, it ran with a simple textual interface, without windows
or a mouse, and computers ran in isolation, with no connection to
a network or other machines. Over time, Microsoft has added
many features and capabilities. Although these may have made
computers easier to work with, they also have expanded the size of
the operating system software and often required more memory.
For technical reasons, measuring program size can be somewhat
tricky (e.g., just what do you count). Also, units of measure change
over time (usually with the unit getting larger as time progresses).
