The price of 2400 bps
| DOI | https://doi.org/10.1108/eb044752 |
| Published date | 01 April 1987 |
| Date | 01 April 1987 |
| Pages | 194-200 |
| Author | Howard Falk |
| Subject Matter | Information & knowledge management,Library & information science |
HARD
WARE
corner
HOWARD
FALK The price of 2400 bps
If you think a modem that can handle 2400 bits per
second (bps) is an unnecessary luxury, it is time to
take another look at what these units offer.
Users who have watched a 300 baud modem
slowly eke out text, and then have compared that
speed with the freer pace of a 1200 bps modem,
will have no doubt which is the best choice, par-
ticularly since the prices of 1200 bps units are lit-
tle different from those for 300 baud modems.
Today, 1200 bps modems are available starting at
about $100-150 and ranging up to $600 or more.
Prices of particular units depend on the perfor-
mance and features they offer, and the willingness
of
users
to pay for intangibles such as brand name.
A 2400 bps modem will cost $200 or so above the
price of a 1200 bps unit. The 2400 bps modems
discussed in this article run from $395 to $765.
Minutes of telephone connection time, at least
over ordinary dial facilities, are not free. Thus,
many users will be able to justify the cost of a 2400
bps modem on the basis of savings in transmission
costs.
Suppose you plan to send thirty minutes'
worth of text a week with your modem. If your
calls are not local ones, telephone costs may run to
about
$ 10
a week, so a savings of
50%
would save
you about $5 a week and it would take forty weeks
to save enough on telephone costs alone to justify
buying a 2400 bps modem.
Users who upload or download information
from online services can look forward to saving on
connection-time fees as well as telephone line use
when they employ a 2400 bps modem. Although
online service at 2400 bps only started a year or
two ago, it is now widely available. Computer
communications carriers, like Tymnet, Telenet and
Uninet are all equipped to carry 2400 bps traffic.
Among online information providers, the only
question about 2400 bps service seems to be what
added cost, if any, users have to pay for the faster
service. At CompuServe, for example, 2400 bps
service now costs the same as 1200 bps. The same
is true at Dialog and Dow Jones News/Retrieval —
neither imposes a surcharge for use at the faster
speed. However, users of Geisco (General
Electric) online services will pay an added
$ 10
per
hour for the privilege of 2400 bps operation.
Lower speeds are included
Users who buy 2400 bps modems get a three-in-
one bargain, for all these units — without excep-
tion — offer operation at 300 baud and at 1200
bps,
as well as at 2400 bps. In fact, a whole group
of common features is shared by almost all 2400
bps modems. These features include automatic
detection of the maximum transmitting speed of
the modem at the other end of
the
communications
link, and automatic adaptation to that speed, as
well as the ability to accept transmissions at
speeds from 110 to 2400 bps. Some units can ac-
cept input at up to 9600 bps and many will take
very slow input at speeds down to virtually zero
bps.
Most 2400 bps modems are now based on in-
tegrated circuit chips, with virtually all basic
modem functions packaged in a single chip. It is
the semi-conductor manufacturer, rather than the
modem vendor, that now builds in the basic
modem functions, so it is not surprising that there
are common features among 2400 bps modems.
Other common features include the ability to do
either pulse or tone dialling, provision of a speaker
to track the progress of calls as they are being
made, built-in self-testing when the unit is turned
on and, for externally-mounted modems, display
of modem status at the panel of the unit.
An international standard
All the 2400 bps modems discussed in this article
operate in accordance with the CCITT V.22 bis
standard which is observed in many countries
throughout the world. These modems may not be
able to run from the electrical power supplies of
countries outside the United States, but they will
be able to communicate with equipment that
shares adherence to that standard.
Standard commands are used
We can thank modem chips for the wide
availability of
a
shared set of common commands.
Although there are no official industry standards
for the commands that control modem operation,
virtually every 2400 bps modem uses the same set
of 'Hayes' (sometimes called 'AT') commands.
These can be keyboarded by users to get their
modems to behave as desired, or can be incor-
porated in software used to control modem opera-
tion. Hayes, a company that sells its own modems,
added speaker volume control and synch/asynch
commands to the list when 2400 bps modems
were introduced. Other 2400 bps modem vendors
have composed their own additions to the Hayes
commands, and these can be of value in managing
the special features offered by these vendors.
Modem chips also provide status indications,
which can be used to display, on the user's com-
puter screen, what the modem is doing. However,
the wording of these displays is a matter of vendor
discretion. Some have chosen very simple, one
word indications, others have spelled them out in
more detail, still others appear to offer no status
displays at all. These displays are probably most
194 The Electronic Library, August 1987. Vol. 5, No. 4.
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