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BOOT CAMP 046
MODEM MADNESS PART 1
Computers and telephones don't really mix. The signals
whizzing around inside your PC are made up of streams of rapid, precisely
contoured digital pulses. The telephone system -- at least the part that
connects your home to the exchange -- is designed to handle comparatively slow,
undulating voltages. In order to connect a PC to a telephone line and
communicate with other computers it needs a device called a modem. Its job is
to translate digital bits and bytes into audible tones, and back again.
Quite honestly it's a wonder that modems work at all, let
alone achieve the kind of data transfer speeds that are now possible. However,
the fact that modems and Internet connectivity cause so many problems clearly
demonstrates that we're dealing with technologies based on compromise. There
are fast and efficient alternatives, such as ISDN and the recently launched BT
Highway system, however the cost remains prohibitive for the majority of
domestic PC users. The bottom line is that we're stuck with modems and analogue
telephone lines for a while yet, so we might as well make the best of it. This
week we'll look at how it all hangs together, next week a closer look at speeds
and standards, what's involved in upgrading, and digital phone lines.
We'll begin with a brief guided tour. Know your modem. There
are two sorts used with most desktop PCs, internal models that live inside the
PC box and external types that connect to one of the PCs serial ports. External
modems are a little easier to deal with when things go wrong, though the fact
that they require extra cables and a separate power supply means there are more
things to go wrong in the first place… Nevertheless they're easy to replace and
the row of winky lights on the front panel means you can keep an eye on it and
see whether or not you or your Internet software has disconnected at the end of
a session.
Hardware faults are quite rare and normally caused by
something fairly obvious like a loose cable or malfunctioning power supply.
Internal modems can sometimes work themselves loose from their sockets. Modems
are also susceptible to damage by high-voltage spikes coming down the telephone
line; if yours stops working after a thunderstorm it has almost certainly been
fried by a nearby lightning strike.
One of the reasons connectivity and modem problems can be so
difficult to diagnose and cure is because there is so much controlling and operating
software spread out all over the place. On most Windows 95 and 98 PCs there are
at least four key locations. The main set-up controls can be found in 'Modems'
in the Control Panel. A modem's relations with the host PC is handled by Dial
Up Networking (see My Computer), Internet Browser software often has its own
set of modem controls and there's another set of configuration options in
Device Manager, (under System in Control Panel).
It's worth acquainting yourself with some the settings,
maybe even taking a few notes when everything is working properly, so you have
a benchmark if things turn nasty. Do not on any account mess with anything and
when you open dialogue boxes always close them with the Cancel button, so any
changes you may have accidentally made will not be applied.
Start with Modems in Control Panel. Make sure the modem
model number and speed listed under the General tab are correct. Click on the
properties button, the General tab will show the communications port it is
using, the Maximum Speed setting should always be higher than the modem's top
speed, it is usually safe to leave it on the fastest 115200bps setting. On the
Connection tab under Connection Preferences, Data Bits is almost always set to
8, Parity is None and Stop Bits 1. Now click the Port Settings Button, the
'FIFO buffer…' box (see Jargon Filter) is normally checked on Pentiums and PCs
made in the last three or four years. The positions of the two sliders will
vary; it's worth trying a lower setting if you are having intermittent
problems, such as dropped connections or corrupted data. Go back to the
Connection tab and click on the Advanced button and note which items have been
checked, they will vary according to your browser software, Flow Control and
Hardware RTS/CTS settings are generally enabled.
The next stop is your browser. Look for menu items like
Options, Preferences or Internet Options. These will contain some or all of the
main settings used for your modem connection. Unfortunately it's impossible to
generalise as there too many variations so familiarise yourself with the
settings, preferably when everything is working normally. Internet browser
software is notoriously flaky; some programs can be very territorial and will
not co-exist with rival software. The best advice is to only have one browser
on your PC at a time, and when you come to uninstall, make sure every last file
fragment is removed. Always use the browser's uninstall utility -- assuming it
has one, not all of them do -- or make it a rule never to load Internet access
software unless you also have an uninstaller program like CleanSweep or
Uninstaller on your system.
There's a lot of information contained in Dial Up Networking
and like just about everything to do with modems and Internet connectivity most
of it is gobbledegook that really needn't concern the average user, until it
goes wrong… Right click on your Dial Up Connection icon and select Properties.
Once again, look and take note but don't touch anything, unless you know what you
are doing. The Device Manager which lives in the System icon on Control Panel
is a good place to check if a sudden problem arises, if you see a yellow-ringed
exclamation mark next to the Modem listing then there may be a driver or
resource conflict. To resolve it start the Conflict Trouble-shooter utility by
typing 'Conflict' in Windows Help.
Next Month: the need for speed, installing a new modem and
digital telephone lines
JARGON FILTER
FIFO
First in first out -- a efficient method of handling data
whereby information is processed in the order it is retrieved or stored
ISDN
Integrated Services Digital Network -- a specialised
high-speed digital telephone line for carrying data and high quality speech
MODEM
MOdulator-DEModulator -- an electronic device that turns
digital data into audio tones -- and vice versa -- enabling computer
information to be sent down ordinary domestic telephone lines
TOP TIP
If your phone is connected to a digital exchange and you
have BT Call Waiting or Call Minder services you may experience problems with Internet
connections. Windows 95 and 98 can automatically switch the Call Waiting bleeper
off before you connect. Open Modems in Control Panel and select the General
Tab. Click on Dialling Properties and check the box marked ' To Disable Call
Waiting Dial', (or 'How I dial from this Location'), in the adjacent box enter
# 43 # (hash 43 hash). You will have to manually switch Call Waiting back on
again after you log off by dialling * 43 # (star 43 hash). Call Minder
generates a 'stutter' dial tone to let you know you have a message waiting,
this does not agree with a lot of modems, so before you go on-line pick up your
messages by first dialling 1571.
NEXT
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