Hardware Reference
In-Depth Information
For example, in my area the basic cable modem service from Comcast costs around $45
per month and has an average (not peak) speed of 12Mbps. Divide $45 by 12Mbps, and
the cost is $3.75 per Mbps. The only extra equipment generally required is a cable mo-
dem, which you can purchase for around $50 or rent for around $3 per month.
By comparison, the basic DSL service from AT&T costs around $20 per month (it can
be as low as $10 per month if you qualify for that rate) and has a speed of 0.768Mbps.
Divide $20 by 0.768Mbps, and the cost is $26 per Mbps, or only $13 per Mbps at the $10
rate.TheonlyextraequipmentgenerallyrequiredisaDSLmodemandsomemicrofilters,
which you can purchase for around $50 or rent for around $3 per month.
How does a typical 56Kbps modem compare, assuming 50Kbps (0.05Mbps) download
speeds?Usingthebasicdial-upservicefromNetZero($10permonth),thecostworksout
to $200 per Mbps. That is 53 times more money per Mbps for service that is 240 times
slower than a typical cable modem.
The services offered in my area stack up as shown in
Table 16.2
, listed from slowest to
fastest download speed.
Table 16.2 Comparing Connection Types and Speeds
Dial-Up Modems
In areas where broadband connections are not readily available, many people still rely on
dial-up modems. This section covers dial-up modems in detail.
The word
modem
(from modulator/demodulator) basically describes a device that con-
verts the digital data used by computers into analog signals suitable for transmission over
a telephone line and then converts the analog signals back into digital data at the destina-
tion.Becauseyoumustdialatelephonenumbertoreacharemotecomputer,thesedevices
are also referred to as
dial-up modems
. Although dial-up modems are generally thought
of as analog devices, the newer 56K (V.9x) modem connections are actually digital. The
