154 Understanding the Numbers
decisions, tax services, accounting standards (GAAP and GAAS), continuing
education courses, and many other topics are available on CD.
Today, DVD ROMs, which have roughly ten times the capacity of CD
ROMs, are becoming popular and in many cases replacing CD ROMs. DVD
popularity is being driven at least in part by the fact that a single DVD can ac-
commodate the massive amount of data necessary to digitally store the sound
and pictures of a full-length feature movie. Recordable DVD drives are now
becoming reasonably priced. With their ability to read both CDs and DVDs
and their ability to record DVDs, one would expect that recordable DVD
drives will soon replace CD drives in new computer systems.
Modems
Modems are devices that allow computers to communicate with each other
using standard telephone lines. In the past few years, modem technology has
increased the speed of data communications over standard telephone lines to
speeds more than 10 times higher than in 1990. However, there is a practical
limit to how fast computers can transmit data over ordinary telephone lines—
currently about 56 KB (kilobit—a thousand bits) per second.
Because of the limitations of telephone lines, alternatives have been and
are being developed. Cable modems, which use cable television wires, and
DSL connections, which use regular telephone wires but with a new technol-
ogy, both have the capability of transmitting data at rates higher than 1 MB
(megabit) per second. While both technologies are spreading quickly, neither is
yet available in all geographic locations. In addition, satellite data service, sim-
ilar to satellite television service, is an available high-speed possibility for data
communications.
Network Adapter
Whereas modems connect computers using phone lines, network adapters
allow computers to directly communicate with each other over wires or cables
that physically connect the computers. In most office environments, the vari-
ous computers are interconnected through a local area network (LAN) so that
they can share printers, data, access to the Internet, and other capabilities.
Today, the dominant type of LAN is called an Ethernet network, and most net-
work adapters are Ethernet adapters. In addition, Ethernet adapters are the
most common form of hardware connection between PCs and cable modems
or DSL connections. An Ethernet network adapter typically costs between
$30 and $50.
Multimedia
By the latter half of the 1990s, most new personal computers came equipped
for multimedia, the ability to seamlessly display text, audio, and full-motion