ModemsModems and Connecting to FreeHOF
"I type and nothing happens"
"You keep hanging up on me."
"You take FOREVER to answer."
"What gives? I only see half a screen"
"My file transfers run at 1/3rd speed."
"I can call whozis fine. I only have trouble here."
"Why do I get No Answer, then Busy, then No Answer, etc?"
Read my fingers: very few communication problems reported to sysops involve modem setups, modem quality or modem design at our end. Assuming there is a high quality modem at both ends, 6 of the 7 problems noted above are caused by telephone lines inadequate to support high speed connects. Can you tell which one is not? (Answer below.)
Here are some common problems and their solutions, but first a little general orientation. The HELPFUL(?) HINTS begin on line 142.
A common mis-perception among computer users is to imagine that telco (TELephone COmpany) networks are silent, transparent conduits. High-speed modems which mask line noise enhance this illusion.
"I was 300K into my transfer and you dropped carrier on me."
Generally, all these problems can be attributed to local or long-distance communications network issues better known as
Problems in signal transmission take many forms, and arise at many points in the signal path. Here's a typical analysis of a problem call, from a USR ATI6 report. The caller complained of "buffered typing, slow system response and slow file transfer."
Chars sent 11813 Chars Received 147 Chars lost 0 Octets sent 7946 Octets Received 146 Blocks sent 269 Blocks Received 53 Blocks resent --> 275 <-- (errors needing correction) Retrains Requested 0 Retrains Granted 0 Line Reversals 0 Blers (lineburst) --> 173 <-- (Block errors) Link Timeouts --> 35 Link Naks --> 1 Data Compression V42BIS 2048/32 Equalization Long Fallback Enabled Protocol LAPM Speed 14400/7200 (V.32bis speed downshift) Disconnect Reason is DTR dropped
The caller said the buffered typing, slow system response and slow transfers were the BBS's fault. The real reason? Look at Blocks Resent and Blers (Block errors). They reveal it was a crappy connection.
When the local telco is having a bad day even the sysop gets typing lag when he calls his BBS over the shortest outside route - going through just one telco switching office. His first thought might be to tear into things and find "the problem." He soon learns to wait a day until the telco lines dry out. When they do, the buffered typing disappears until they get wet again.
It doesn't have to be rain or snow. High humidity can do it, even squirrel piss.
Some bargain-priced high speed modems aren't as good at dealing with line problems as more costly modems. Did you think the extra $ for the better units bought only a nameplate? Check out the tests in back issues of PC-Mag, PC-Week, INFOworld, etc.
Money - and big names- were nearly a guaranty of trouble-free connections at 14400 baud, but this is not so using V.FC or V.34 (28800) as of 1995. Whether it's the standards, the technology, the implementation or the over-stressed telco equipment, 28800 has not made us happy campers.
Since the telco only guarantees to provide success up to 14400 we shouldn't be surprised that it's flaky above that. Still, we're surprised. My advice is to count yourself lucky for every long distance download that runs faster than 1650 cps. Ok, 2200 cps isn't the 3350 cps a 28800 modem "is capable of" but it means a shorter LD phone call than 1650.
Trouble getting or keeping a connection with a 28800 is another matter. Be mad as hell when you have that problem. But not at me. I didn't write the standard, design the chip or build the modem, and I run the best modem I can find for BBS use, according to sysops who tried them all. They settled on USR V.Everything and that's what's here.
Some popular, low-cost modems are terrific when the connection is clean but are dead fish on noisy lines.
"I can call Captain Billy's Whiz Bang BBS just fine but not you."
Local callers no less than long-distance callers can have problems with telco switch networks. Captain Billy may be in a different telco exchange like 973 handled by equipment north of town. I'm on the 293 exchange in the downtown office. Each exchange has problems all its own.
"Sometimes when I call a BBS I get No Answer, then Busy, then No Answer again. How can it be both Busy and not answering? "
You are playing the popular Board Game "Ring, No Answer." For once that's not a telco problem. The BBS modem isn't answering. The Busy is because you have called while someone else is playing the game. Either the BBS is down for maintenance or just down, or the modem is crying for help. Curiously, this is the normal mode for the HAYES 800 BBS, damn it.
THE HARDWARE -- MODEMS
Mother taught you a MODEM is a MOdulator-DEModlator device to convert digital signals your computer understands to/from analog signals the present telco equipment can carry.
A modem is smarter than a baby or a cat but not as smart as you. You can ask it questions and it will answer, tell it to do something and it will do it. Send it SETTINGS and it will set itself. But unless you tell it specifically to *remember* those settings, it won't.
Communications programs are supposed to let you talk TO the modem as well as through it, though some make it difficult by presenting a menu interface and even a GUI! The magic command to speak to modems is AT
AT tells the modem to treat what follows as a request for the modem to do something, like display its settings or set itself and report back to you. If the computer is communicating to the modem, and the modem is basically set up properly, it should answer back ù OK ù or ù ERROR ù or some message equally as clear.
It is vital that a new modem user spend some time reading the manufacturer's instruction manual, and locate the "Commands Summary and Explanation " pages, or equivalent.
Most modems will display an "Active Profile" of settings and one or more "Stored Profiles." User-defined stored profiles are held in what's called NRAM memory (aka NVRAM -- non-volatile random access memory.). When the modem is sent an ATZ (that command is nearly universal for Reset), NRAM settings become the Active settings. Until you send a special command to change NRAM settings, ATZ will always bring back the old settings.
That means you can test modems with experimental AT commands all day long without losing your old settings. Unless you save settings to the NRAM, the modem will forget all the new stuff when it's powered off or undergoes an ATZ reset. Your comm program almost surely does an ATZ when you load it, by the way.
Modems often come with "factory settings" fixed in one memory and with changeable default settings in the NRAM memory. NRAM settings often need to be changed to function with BBSs and high-speed communications. See the modem manual.
Modem commands vary from manufacturer to manufacturer. AT&W is -often- the command to save the settings to NRAM, but many modems require something else. Read your manual because you MUST KNOW your command to save to NRAM memory.
Repeat that? Sure...
High-speed modems require serial cables which support hardware (CTS/RTS) flow-control. Old printer cables won't necessarily work. Old printer cables won't necessarily work. Old....
If your modem is internal, needing no cable, there's no cable problem. But with an internal modem you won't see THE LIGHTS that tell you what a modem is doing and what kind of connection was made. Lights are helpful - a must for trouble-shooting - but more important, lights are cool. The USR V.Everything has 12 of them. The Hayes Optima 288 has 8.
If you are using a V.FC or V.34 modem and it works, you have a buffered (cacheing) UART on the internal modem or on the serial card controlling the external modem. The UART is an I/O chip that controls.....I/O. A buffered one stores a few characters during transmission and releases them on a first-in, first out basis. Without this a high speed modem will see dropped characters, CRC errors and aborted downloads, assuming it connects at all.
One school says a buffered UART is REQUIRED for 9600 and 14400 modems; another school says no. I say it's a $20 chip. If you don't have it, get it.
The UART is a large chip, easily $20 worth in size alone. Commonly you'll see two side by side on a serial card. There are two because these cards commonly support two serial ports and each needs a UART. If only one port is enabled the second socket may be empty, along with two smaller sockets.
Unbelievable but true: good UARTS can become bad UARTS without asking permission. If your successful modeming comes to an end due to dropped characters, CRC errors and aborted downloads, suspect the UART. At the very least, re-seat it in the socket by pushing down hard. They work loose. Trust me.
Altogether now: "A non-buffered UART or one that worked itself loose in the socket can cause dropped characters, CRC errors and aborted downloads. " Very good.
UARTs that buffer have the number prefix 16550 which may or may not be followed by letters A, C, F, and N. (Cis the choice of the experts as of 5/95.) If you'd like to check to see if your UART is buffered without opening the case, do it with software. There are several pgms on FHOF that report the UART type. See File Directories 3 & 4 (Communications) and 5 & 6 (Diagnostics.)
It's a fact of life that programs designed to shield beginners from their modems make diagnostics more difficult.
Tech Support: "Type AT and tell me what happens."
If you are using a comm program that came with your modem, like MTEZ or QLII or an old version of Crosstalk or Windows Terminal, stop wasting your time. Download one of the comm programs available in Conference 3 (free) or 4 (shareware.) You know, of course, that you can't run a Windows program if you aren't running Windows and you shouldn't if you are. Got that? It means Windows and WIN comm programs have been known to cause communication problems that wouldn't happen with DOS.
I don't say that because I despise Windows. I say it because the people who DON'T despise Windows say it.
Can't download? Read on.
A comm program communicates with your modem and handles many tasks. Like the modem, it has user-defined settings. It must be configured for your modem, your computing environment and my BBS if it's to successfully call here.
Commonly in a communications pgm you need to select the:
comm port (generally #1, 2, 3 or 4.)
IF YOU HAVE A 14400 OR FASTER MODEM
Flow Control CTS/RTS Hardware flow control (ON)
This means lock the DTE rate to the Dialout Speed, not the connect speed. DTE is the speed between YOUR modem & YOUR computer. It should be locked at the highest rate it can handle (by trial & error) and never less than 38400 with a high speed modem.
Modem initialization string ATH0 is common. H0 means modem on-hook, needed to get a dial tone. Edit out long INIT strings. With some modems, an ATZ reset is the best INIT string. With others it causes problems. If you use the modem for two very different purposes such as running a BBS (answering calls) and calling out, each may need its own INIT string called from its own NRAM. Many modems have more than one NRAM. Read your whatsit.
General philosophy -- set up your modem with the appropriate settings and write them to the modem's NRAM memory. Keep setup strings & changes as short as possible and don't let them reset your modem unless there's been a demonstrated need to reset.
Finally, you probably need to tell your comm program a little about how your hard disk is set up, or: THE "FEATURE" THAT TRIGGERED 100,000 CHANNEL 1 SUPPORT CALLS.
Procomm, in its seminal 2.4.x version that everybody uploaded all over the universe, requires a Default Download Directory to be specified in ALT-S setup, "Files and Paths." If the user doesn't type one in, deadsville on downloads. Procomm's failure to have an error message guaranteed there'd be screams for Help!
Believe it or not rain water and dampness short out telco facilities; winter storms coat transmission lines with pounds of ice; falling limbs bring down wires which lay in the street. At these times the telco is not at its best. Strange but true.
You cannot use a conventional modem to send FAX. It must have specific FAX capability in the design.
A FAX modem switches speeds, 14400 down to 2400, depending on line conditions and the equipment at the other end. It also switches among at least 4 modulation techniques (V.17, V.29, V.27 and V.21), and has its own elaborate procedures for negotiation, determining what bit density can be supported, what compression to use, etc. Don't bother reading the manual. What there is shows up in an Appendix not intended for us. If it doesn't work with your FAX program out of the box, call software support for help before calling the modem manufacturer.
A FAX modem should have the ability to send an identifier signal as soon as it dials out and as soon as it picks up. There are a number of products on the market to allow a FAX and phone to share the same line. To use one, the FAX must be able to send an identifier, or two faxes can sit there waiting for each other while the long distance bill mounts up.
Elsewhere Around the World
In the US there's a federal telco rule (universally ignored) stating that after getting a busy signal we must wait 60 seconds before re-trying the number. Few people know about it and no one observes it, although I have an electronic telephone where it's built in. It's also possible the rule was rescinded and no one told us, which is why this phone was so cheap from Damark.
Anyway, in some parts of the world they take such things VERY seriously and modems cannot be sold in those countries that don't conform. The legal strictures you see below must be built into the modem chips before the modem can be imported. Here's a short list.
It's much more than just laws against war-dialing. Check especially France (the planet idiots) and Austria which hasn't done anything right since the emperor died.
SINGAPORE: 5 retries without delay, 2 minute delay between next 4 retries. After 10 tries the number goes on the FORBIDDEN LIST and stays there for TWO HOURS.
BELGIUM: 1 minute delay between each retry, after 5 tries the number goes on the FORBIDDEN LIST and stays there for ONE HOUR.
ITALY: 5 retries without delay. 2 minute delay between next 4 retries, after 10 tries the number goes on the FORBIDDEN LIST and remains there for TWO HOURS.
FRANCE: 2 minute delay after 1st call, 4 minute delay after 2nd call, 6 minute delay after 3rd call, etc. After 6 tries on a busy number it goes on the FORBIDDEN LIST and remains there, locked out FOREVER.
AUSTRIA: No delay between retries. After 3 tries to numbers that answer but have no modem tone the number goes on the FORBIDDEN LIST. After 11 tries to numbers which are busy the number goes on the FORBIDDEN LIST. Numbers on the FORBIDDEN LIST remain there, locked out FOREVER.