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- DEMON INTERNET LTD.
- ===================
- 42 Hendon Lane
- Finchley
- London
- N3 1TT
- 0181-349 0063 (London)
- 0131-552 0344 (Edinburgh)
- 0181-343 3881 (HelpLine)
- email internet@demon.net
-
- MODEM.TXT - INFORMATION ON CONFIGURING A MODEM FOR CONNECTING TO THE
- INTERNET
- Last updated 5th September 1994
-
- The latest version of this document is available from
- ftp.demon.co.uk:/pub/doc/Modem.txt
-
-
- Contents
- ========
-
- 1. General
- 2. Essentials
- 3. Telephone Exchange
- 4. Internal Modems
- 5. Which Phone Number
- 6. Modem and Telephone Leads
- 7. Serial Chips
- 8. Speed
- 9. Trouble Shooting
- 10. Software and Other Factors
- 11. Help for Specific Computers
- 11.1 IBM PC Compatibles running DOS
- 11.2 OS/2
- 12. Individual Modem Settings
- 12.1 US Robotics/Miracom
- 12.2 BT NS 2232 M
- 12.3 Dowty
- 12.4 Dynalink
- 12.5 Gateway
- 12.6 Mistral
- 12.7 Multitech
- 12.8 Supra
- 12.9 Yoriko
- 12.10 Zoltrix
- 12.11 Zoom
- 12.12 Zyxel
- 13. Testing
- 14. Finally
-
-
- 1. General
- ==========
-
- This document will point out some general essentials and advice on
- setting up your modem. A section at the end discusses specifics
- regarding a DOS setup running the KA9Q NET.EXE program. Due to the vast
- combinations of computer and modem setups it is impossible to give
- specific help for all types.
-
- Making an Internet (IP - Internet Protocol) connection via a modem is
- very different from a standard dial-up connection. Do not assume that
- just because you can download from a BBS (and maybe upload) or use other
- services that you have your communication (comms) set-up 100% sorted out.
- Due to the nature of IP, if you get errors, throughput can be hit very
- badly. Under IP information is sent in packets and for maximum speed
- these should generally be as large as possible up to a maximum of about
- 1500 characters. If a packet gets messed up (garbled) its entire
- contents will have to be resent - hence a large speed degradation may
- occur.
-
- One exception to this is when an interactive sessions are sharing a
- TCP/IP link with more voluminous transfers such as NNTP or SMTP. In this
- case it can be preferable to have smaller transmission units (Maximum
- Transmission Units setting or MTU) so that keystrokes/screen updates will
- fit into the data stream with less delay. If a large MTU is used this
- can lead to what feels like a jerky or intermittent session.
-
- Enough of the technical parts, there follows some sound advice that
- everybody should take note of.
-
-
- 2. Essentials
- =============
- Correct modem settings:
-
- Full hardware handshaking (CTS/RTS),
- Flow control
- XON/XOFF (software handshaking) set to off
- Settings must be bi-directional where appropriate.
-
- A full specification modem cable (open yours up - if it has
- only 3 wires it is no good).
-
- A serial chip that can cope with the high speeds (if using a
- high speed modem). Extended memory drivers and Terminate Stay
- Residents (TSRs) etc. can interfere with the handling of
- interrupts from serial chips.
-
-
- 3. Telephone Exchange
- =====================
-
- The Demon Internet Service (DIS) is on modern digital exchanges
- so you should have little trouble with ringing tones etc when
- connecting to us. If you are on an older exchange, your modem
- may not recognise the dialling tone. If this happens, look in
- your manual and change the setting that overrides the dial tone
- recognition.
-
- Note that when you make changes to a modem's settings you
- should always reset the modem first, make the change and then
- save the settings. You will need a comms or "terminal
- emulation" package such as Telix, Procomm, Window's Terminal, Z-
- Term, Microphone etc. Look in your modem manual for
- instructions. Mostly you will be able to type ATZ <return> to
- reset your modem. On a US Robotics/Miracom modem you could
- type:
-
- ATZ Reset the modem
- ATX3 Alter a setting
- AT&W Write the settings to Non-Volatile RAM (NVRAM)
-
- The last bit (AT&W) is useful as it means that when the modem
- is reset, it will remember the settings you have stored.
-
- If going through a private telephone network (or PABX) first,
- you will probably need to dial a number such as 9 to get an
- outside line. Make sure your dial string has this in. You may
- need to separate this from the number to dial by a separator
- such as a comma so that there is a pause to give your telephone
- system time to give you an outside line:
-
- 9,01813434848
-
-
- 4. Internal Modems
- ==================
-
- Internal modems have the advantage of not having a serial lead
- to worry about but the disadvantage of using an extra interrupt
- and generally don't have any lights to let you know what is
- going on. Ensure that the interrupt on which the modem sits
- does not interfere with any others - refer to the setup program
- for your computer and your modem manual. This may require
- altering a jumper (a small connector) on the main computer
- board (mother board) on your computer or on a separate board.
- This should be well documented and is well within the scope of
- the average user. Ensure that the modem is seated correctly in
- the expansion slot.
-
-
- 5. Which Phone Number
- =====================
-
- We have multiple Points of Presence (PoPs) - please see
- /pub/doc/Demon.txt for details. Thus you will have a choice of
- numbers to ring. You may use any of our PoPs at any time.
-
-
- 6. Modem and Telephone Leads
- ============================
-
- Your modem lead should be in good condition and preferably not
- wrapped in a tight circle or running parallel to high power
- cables etc. This will normally only affect longer runs and, as
- your cable should be earthed, will not often be a problem. The
- cable should be connected securely at both ends as should the
- telephone cable. If you suspect your telephone socket may be
- causing a problem then test it with a standard plug in
- telephone. Use the correct type of modem lead - they vary from
- country to country.
-
-
- 7. Serial Chips
- ===============
-
- The type of serial chip (Universal Asynchronous
- Receiver/Transmitter - UART) in use can make a big difference
- to comms performance/reliability. At higher speed the computer
- can sometimes not service the serial chip fast enough to catch
- all of the characters arriving down the line. This problem
- increases if running under a multi-tasker such as Windows,
- certain memory managers and other TSRs.
-
-
- 8. Speed
- ========
-
- Close to every modem user's heart is the speed at which they
- can operate. There are two different speeds: the first is the
- speed at which a modem can talk to another modem; the second is
- the speed at which the modem can talk to its controlling
- computer (the DTE rate).
-
- Firstly, we will discuss the connect rate. A V.22bis modem can
- connect at a speed of 2,400 bits per second. There are 8 bits
- in a byte (a byte is usually one character) so that is a
- maximum of 300 characters per second (cps). Due to start and
- stop bits, each byte will take 10 bits reducing the speed to
- 240 characters per second. When running over IP there is a
- slight overhead and so you will never see this maximum.
- However, as you can (and will) have several things happening at
- once, you will be able to make very good use of your available
- bandwidth.
-
- Many modems have compression protocols built in to them. MNP/4
- and V42 use synchronous connections to provide an error free
- connection between modems, saving the start and stop bits.
- This gives at least a 20% increase in throughput. V42bis adds
- compression, provided that the DTE rate is higher than the
- connection rate. This means that when downloading a plain text
- (or ASCII) file, it is possible to get faster speeds by
- compressing the data. The data is compressed so that the same
- information can be encoded in to a smaller space. The
- receiving modem will of course unscramble the data for you. If
- news normally flows in at say 200 cps, then, on a 2400 cps
- link, you have up to 44 cps left at the same time for mail,
- telnet'ing, ftp'ing etc. Compression techniques do not work as
- effectively on binary files and make very little difference to
- pre compressed files (such as .zip, .zoo, .lha etc.).
-
- Note that MNP5 will usually degrade throughput on an IP link
- due to the packet based nature of it's compression method.
- V42bis does not suffer this problem as it is capable of
- optimising itself dependent on the type of data being
- transferred.
-
- Now we will discuss the second speed - the speed at which the
- modem and computer communicate with each other. This is called
- the Data Terminal Equipment (DTE) rate. If you have a slow
- modem, e.g. a 2400 baud one without MNP or V42, then it will
- probably only work correctly when talked to by the computer at
- the same speed. For the facts on your particular modem and
- computer you should refer to your manuals. On faster modems
- you will only be able to take advantage of some of the
- compression features by making the computer talk to the modem
- at a faster speed than modem is talking to the remote modem
- down the telephone line. Thus you should talk to a 9600 modem
- at 19200 or even 38400. You should check the maximum speed at
- which the serial port on your modem can talk and then set your
- communication package to work at the highest mutually available
- speed. Don't forget that without a buffered UART you are
- unlikely to sustain reliable high speed comms above 9600 baud.
-
- Please note that we only support modems capable of V22bis
- (2400) and upwards. If you have a US Robotics/Miracom HST
- modem, you may not get very good throughput in HST mode. In
- practice HST mode is fine if FTP'ing from a site without
- anything else happening (sending mail etc.) as it works fine in
- one direction at a time only.
-
-
- 9. Trouble Shooting
- ====================
-
- If you are getting garbled characters on the screen then
- something is wrong! Garbled characters are often a sign of
- mismatched speeds, lack of handshaking or a non-locked DTE
- rate. If you get as far as the login prompt but no further
- then make sure that your dialler script is working on 8 bit
- standard comms: 8 bits, no parity, 1 stop bit. See
- /pub/doc/Demon.txt for the full logon script details.
-
- Having checked your setup according to the information above,
- try reducing the speed at which the computer talks to the modem
- (if using a high speed modem) until the connection works. If
- you have to do this then either you are attempting to drive
- your computer or your modem at too high a speed, or you have
- other processes running which interfere with the correct
- running of your serial communications (as per Serial Chips
- above).
-
- If you have finished your live session and log off you may
- sometimes find that your phone line is not dropped. This can
- result in an unwelcome phone bill! There are a number of
- computer/software specific solutions to this problem and some
- answers are given in /pub/doc/Support.faq which may have been
- included in your installation. One thing to check on your
- modem is that the setting that makes the phone line drop when
- the computer tells the modem that it has finished, is on. The
- computer uses the serial port and drops DTR (Data Terminal
- Ready) and the modem spots this and hangs up the line. The
- setting often &D2 and you should read the section below which
- tells you how to set this. It is definitely &D2 for US
- Robotics, SupraFax and Dowty Quattro modems.
-
- If your modem sometimes seems to fail to recognise a ringing
- tone, reporting it as BUSY. This can be cured by adding a
- comma after the dial number, e.g. "ATDT0813434848,". This
- makes the modem pause and ignore the first rings which it
- sometimes things is a busy single. Some US Robotics modems can
- exhibit this problem.
-
- ATZ is the command that resets the modem. Setting your
- initialisation string to ATZA0 etc where A0 is the
- initialisation string is very likely to fail. This is because
- the modem takes a while to reset and throws away the data being
- sent to it in the meantime. Some people beg to differ on this
- point. However it is certainly true on US Robotics modems.
-
- Just to confuse matters further there are often some switches
- on the modem which you can use to make further settings or to
- default to different options. These are referred to as DIP
- switches. Mostly, the advice contained in this document,
- refers to modems that have not had their switches tampered
- with. If you have the manual for your modem (and I hope you
- have!) then that will probably tell you what the default
- factory switch settings were. Make a careful note of the
- current settings and then change back to the factory defaults.
- If you already use your modem with other packages, make sure
- they still work. These DIP switches must be set to ensure that
- the reset command ATZ resets the modem to the stored values.
- On some modems it is possible to make ATZ restore to factory
- settings which rather defeats the object of configuring it!
- Some modems have ATY commands instead of DIP switches and so it
- is important that the correct ATY command has been used.
- Fortunately, the default will ok if no ATY command has been
- issued.
-
- There is a section below which specifically refers to problems
- that may be encountered by PC users.
-
-
- 10. Software and Other Factors
- ==============================
-
- By configuring your software correctly you can make significant
- improvements to an under performing communications connection.
- Things to check for include badly fragmented disks (run a disk
- de-fragmenter such as Norton's Speed Disk), no disk cache, no
- or insufficient buffering inside the software and unnecessary
- checking protocols or indexing taking place. Refer to your
- software's instructions for details on these.
-
-
- 11. Help for Specific Computers
- ===============================
-
- Some extra comments for some operating systems which may be of use
- follows.
-
- 11.1 IBM PC Compatibles running DOS
- ===================================
-
- In addition to the above info there is some specific advice
- below for those of you running DOS.
-
- Some modems send back "OK" when sent ATZ (the reset command)
- even though they are not ready. This means that the dialer
- program will try to ring out even though the modem is not
- ready. The effect is that you will see ATZ on the screen
- followed by OK and then the program will not dial. Eventually
- it will time out. To avoid this, send AT instead of ATZ in the
- modem initialisation string.
-
- Extended memory drivers can interfere with the correct
- operation of your serial communications. If you suspect this,
- rename your CONFIG.SYS and AUTOEXEC.BAT files and then reboot
- your computer to see if the connection improves.
-
- If you have a V.32bis 14,400 modem you will probably want to
- talk to it at 38,400. Unless you have a suitable serial chip
- then you will get errors and, as explained at the start of this
- document, this can seriously impact the throughput. When
- running NET.EXE you can type asystat at the net> prompt and
- information about your serial comms will be printed to the
- screen. The interesting parameter is the third one on the
- second line, 'hw over'. This shows how many hardware overruns
- (characters lost because they weren't fetched from the serial
- chip in time) have occurred. These overruns are usually due to
- lack of either a buffered UART or hardware handshaking.
-
- As already stated, for maximum performance you will need to
- have a buffered chip. For this you will need a 16550A - this
- is the number that is written on the chip. The asystat command
- will tell you if a 16550 is detected. Unfortunately, even top
- manufacturers overlook this area so it is quite likely that
- your chip is below par.
-
- If in doubt, open up your computer and locate the serial chip.
- If it is not a 16550 then it might need replacing. If you are
- handy with a soldering iron you could replace it, but this is
- not advisable unless you are really confident. If the chip is
- socketed then it can be removed and a 16550 (costing about #16
- - we sell them) be put in its place. If not then you could buy
- an extra serial card with a 16550 already on it costing from
- around #30 to #70 depending on the specification.
-
- Some internal modems use a 16450 with a large buffer (1K) and
- this may be enough to stop hardware overruns.
-
- If you are using a standard serial port then the settings
- offered for COM1, 2, 3 or 4 in the configuration program in
- DIS.EXE will probably be fine. Otherwise you should refer to
- your manuals and enter the appropriate IRQ number and I/O base
- address.
-
- If you install an extra serial card then be aware that if you
- have, for example, a mouse on COM1 then you should not use COM3
- for your modem using the default IRQ setting as they share the
- same interrupt.
-
- There is another factor that can impede throughput and that is
- software overruns. Using the NET.EXE software, at the net>
- prompt having just received some news or ftp'd a file, type
- asystat and look at the figure before sw over. If this is not
- 0 then you are getting software overruns. To fix this,
- increase the buffer size in the attach line near the top of
- autoexec.net:
-
- attach asy 0x3f8 4 ppp sl0 4096 1500 38400
-
- Alter the 4096 in the above to be 8192, 12288 or higher until
- the software overruns are cured.
-
- More information on tuning is available in
- /pub/doc/ka9q/Tuning.faq.
-
- 11.2 OS/2
- =========
- If intending to run the DIS DOS software in an OS/2 2.x DOS
- session you should get a copy of sio126c.exe and install the
- communications driver in it before running DIS. sio126c.zip is
- available on our ftp server or via our guest download account.
- This is because the standard communications drivers do not pass
- to DOS the buffering of your 16550A buffered serial chip.
-
-
- 12. Individual Modem Settings
- =============================
-
- 12.1 Setting Up a US Robotics/Miracom Modem
- ===========================================
-
- To set up your modem, use a standard communications package.
- Type ATZ <RETURN> and see the response OK. Then continue to
- make the settings. You can type ati4 <RETURN> and ati5 to see
- what your current settings are. For connecting to Demon we
- recommend the following:
-
- B0 V.32bis modulation rather than HST
- C1 Transmitter enabled
- E1 Local echo ON
- F1 Duplex OFF receiving system sends duplicate data
- Q0 Result codes displayed
- V1 Display result codes in verbal (not numerical) mode
- &A3 Enable additional error control indicator
- &B1 Serial port remains at fixed setting
- &C1 Modem send CD (Carrier Detect) on connection
- &D2 Terminal sends DTR (Data Terminal Ready)
- &H1 Hardware CTS (Clear to Send) transmit data flow control
- &I0 Received Data software flow control disabled
- &K3 MNP 5 data compression disabled
- &N0 Variable link speed negotiation
- &R2 Received Data h/ware (RTS) flow controlled by computer
- &S1 Data Set Ready (DSR) controlled by the computer
-
- e.g. type AT&K3 <RETURN>. When done type AT&W <RETURN> to save
- the settings to Non Volatile Ram (NVRAM) so that they are
- remembered when the modem is reset.
-
- Some US Robotics occasionally mistake a System X (and Y?)
- ringing tone for a busy tone and hang up just as the Demon end
- answers. Sticking a pause on the end of the dialling sequence
- stops the modem's response long enough for the Demon end to
- start its negotiating sequence. This means that the confusing
- System X tone is ignored. If the Demon end is busy you just to
- wait a bit longer for the BUSY string, but not as long as the
- setting in S7. Add a pause by adding a comma to the end of the
- string.
-
- 12.2 BT NS 2232 M
- =================
-
- (Note this doesn't work reliably with dial, but does work with
- TIP or with an outboard Kermit script.)
-
- at &f0 s0=0 x7 m2 &u1 &k0 b0 s30=26 &e5 &r1 &d2 &c1 l3
- &f0 - reset to factory default
- s0=0 - suppress auto answer
- x7 - maximum message generation (for diagnostic purposes)
- m2 - speaker always on, so you can hear retrains
- &u1 - RTS flow control
- &k0 - CTS flow control
- b0 - CCITT mode
- s30=26 - CTS follows DCD **, plus defaults
- &e5 - V.42bis (and LAPM)
- &r1 - RTS locked on (??)
- &d2 - DTR is Data Terminal Ready
- &c1 - CD Normal
- l3 - Speaker loud
-
- ** the theory is that it would otherwise try to track RTS when
- that is used for flow control.
-
-
- 12.3 Dowty
- ==========
- Dowty Quantum 144
-
- To configure this modem for CTS/RTS only (hardware
- handshaking):
-
- &k2 Use CTS on transmission
- &u2 USE RTS on receive
-
-
- 12.4 Dynalink
- =============
- Dynalink 1414VE: AT&Q9W1S37=11S48=0M0
-
- &Q9 The modem will attempt V.42bis, fallback to V.42(LAP-
- M), then fallback to normal mode.
- W1 Reports the error correction protocol and the carrier
- speed used.
- S37=11 Sets DCE speed (modem to modem) to 14400bps.
- S48=0 Disables protocol negotiation. Forces LAPM.
- M0 Turns off the speaker. (This thing is loud!).
-
- ATZ or AT&F as the first command as both of these seem to annoy
- the modem into false starts.
-
- ACTIVE PROFILE:
- B1 E1 L0 M0 N1 Q0 T V1 W0 X4 Y0 &C1 &D1 &G0 &J0 &K3 &Q9 &R0 &S1
- &T4 &X0 &Y0
- S00:000 S01:000 S02:043 S03:013 S04:010 S05:008 S06:002 S07:050
- S08:002
- S09:006 S10:014 S11:095 S12:050 S18:000 S25:005 S26:001 S36:007
- S37:011
- S38:020 S44:003 S46:138 S48:000 S49:008 S50:255
-
-
- 12.5 Gateway
- ============
-
- Gateway Telepath modem: AT&K3s48=0s46=138s36=1
-
- The modem works fine at 38400 and most of the time is OK with
- 14400 carrier. On occasion it works better by setting it down
- to 9600 with n0s37=9 added to the init string.
-
-
- 12.6 Mistral
- ============
-
- For an Amber Logic Mistral FX144 modem.
- Use the factory defaults and the following:
- &E4 Forces the modem to reject the connection with
- the
- 'NO CARRIER' message if it cannot establish a
- V42 link
- S31=2 Locks the DTE baud rate to 38400
-
-
- 12.7 Multitech
- ==============
-
- AT&F
- This just resets to factory settings.
-
- From one of our users with a Multitech MT1932ZDXK V32Ter and
- fax modem:
-
- AT&F&E2&E7$MB14400X4M0S0=0
-
- The X4 just gives you full result codes - not essential unless
- you want to
- know exactly what kind of connection you've got.
-
- From a Multitech dealer:
-
- &E4 Hard CTS/RTS
- &BA0 Baud rate altering off
- &E2 V.42 with no fall back to MNP5
- &E15 Compression on
- &D2 Hang up the line when DTR is dropped
-
- 12.8 Supra modems
- =================
-
- Supra 14.4k fax modems need the ROM revision 1.70B or later but
- their ROM revision number is odd. Revision 1.8 or 1.4 are also
- apparently OK.
-
- Information providing features
- Enable all CONNECT, PROTOCOL & COMPRESSION mesgs: s95=41
- loudspeaker control (low volume, on until carrier): l1m1
-
- Modem/PC signals
- modems disconnects when DTR drops: &d2
- DCD follows line carrier: &c1
- Enable hardware flow control: &k3
-
- Speed connection, reject bad lines
- new models, only make LAPM Reliable connections: \n4
- old models, make AutoReliable connections: \n3
- Disable negotiation, make V42 (LAPM) connection: s48=0
- connect at highest shared data rate: n1
-
- Compression
- new models, V.42bis (BTLZ) Enabled, (but not MNP): %C2
- old models, enable data compression (BTLZ or MNP): s41=1
-
- An initialisation string for this would be:
-
- ats95=41 l1m1&d2&c1&k3 \\n4 s48=0 n1 %C2
- ^note the double '\' is needed if typing this
- into some dialer programs
-
- To put this into the modem's memory (NVRAM) type at&w
-
-
-
- 12.9 Yoriko modems
- ==================
-
- Yorikos work OK with a simple AT&F&C1&D2 set-up.
-
-
- 12.10 Zoltrix
- ============
-
- These are one of our user's settings for a Zoltrix v32bis
- internal fax/modem. He writes:
-
- With X4, W1 and V1, I've managed to configure it very nicely to
- redial if the line's are busy after only 5 seconds, report
- CONNECT, PROTOCOL CARRIER, and BUSY
-
- The only bit I'm vaguely unsure about is, whether disabling
- compression (%c0 on mine), disables v42bis also, as I really
- only want to knock out MNP 5. &Q9 I think attempts v42bis,
- falls back to LAP-M+v42, then to normal.
-
- An annoying feature is that at&v only digs out probably a
- quarter of the settings - the '\' and '%' commands don't
- feature; some of them appear extremely useful: %Q for instance
- purportedly reports line signal quality, and %L received signal
- level, which I reckon might be relevant to one recent spate of
- postings, and you can tune up v42bis with others.
-
- S86 stores a connection failure cause code.
-
- OK
- at&v
- ACTIVE PROFILE:
- B0 E1 L0 M0 N1 Q0 T V1 W1 X4 Y0 &C1 &D2 &G0 &J0 &K3 &Q9 &R0 &S1
- &T4 &X0 &Y0
- S00:000 S01:000 S02:043 S03:013 S04:010 S05:008 S06:002 S07:060
- S08:002 S09:006
- S10:014 S11:095 S12:050 S18:000 S25:005 S26:001 S36:007 S37:000
- S38:020 S44:003
- S46:138 S48:007 S49:008 S50:255
-
- Another user writes:
-
- Rom revision (use ATI0 or similar to check) : See below
-
- AT&Q5S48=7S46=138S95=46
-
- Rom revision
- ------------
-
- I have listed what comes out of ATI0 to ATI4 as ATI0
- doesn't make sense!
-
- ATI0 = 14400
- ATI1 = 007
- ATI2 = OK
- ATI3 = V1.410-AP39
- ATI4 = a007880284C6002F
- bC60000000
- r1005111151012004
- r3000111170000000
-
-
- Additional modem string info. (may be of some use)
-
- &Q5 = set error correction mode
- causes the modes to try v42bis, then MNP5, then normal
- connection
- S48=7 = enable V42 negotiation
- S46=138 = error correction with compression
- S95=46 = display extended result codes
- so I can see that i've got error correction
- and compression :-)
-
-
- I also have a line
-
- echo atz > com3:
-
- in my demon.bat file to reset my modem as my fax software
- leaves it in a bit of a state :-( Two 'init' lines don't seem
- to work (not that I'm bothered!)
-
-
- 12.11 Zoom modems
- ================
-
- From one user comes this:
-
- Zoom 14.4X FaxModem Settings
- ============================
-
- These setting are in use to connect to demon both via KAQ9 and
- trumpet winsock (SLIP). The settings enable 14400 bps with V42
- error correction and V42bis data compression. In operation I
- achieve 2600 cps when obtaining mainly text news. Whilst I am
- sure the settings work I do not vouch for the accuracy of my
- interpretation of what they mean!!
-
- To reset modem to stored profile:-
- ATZ - sets to profile 0
- ATZ0 - sets to profile 0
- ATZ1 - sets to profile 0
-
- To store current profile:-
-
- AT&W0 - store as profile 0
- AT&W1 - store as profile 1
-
- For brevity I have left out setting that have no functional
- relevence.
-
-
- Profile Command comments
- E1 ATE1 Command characters echoed
- N0 *ATN0 (zero) Disable auto-mode
- detection; connection speed specified
- by register S37
- Q0 ATQ0 (zero) Enable response to computer (DTE)
- X3 *ATX3 Monitors busy tones; sends
- X2 messages
- Y0 ATY0 (zero) Disable long space disconnect
- &C0 AT&C0 (zero) Forces RLSD (DCD) on
- &D0 AT&D0 (zero) Data terminal ready options
- &G2 *AT&G2 Enable 1800Hz guard tone
- &J0 *AT&J0 (zero)Disable adjusting DTE speed
- &K3 AT&K3 Enable RTS/CTS flow
- control. VITAL for slip connections
- such as Trumpet winsock
- &R1 AT&R1 CTS is always on in
- synchronous or drops if required by
- flow control in asynchronous
- &S1* AT&S1 DSR active after answer
- tone detected and inactive after
- carrier loss.
- &T4 AT&T4 Responds to remote modem
- request for digital loopback.
-
- Registers
- Set using ATSn=v Sets register n to value v
-
- S37 11 *
-
- All lines with an * are for items than are altered fron the
- factory default settings.
-
- We would recommend &d2 otherwise your modem may not hang up the
- line when you have finished your call.
-
- From yet another user: The best I've got so far for the Zoom
- 14.4X is AT&F0W1&C1&D2%C2
-
- &F0 (manufacturer's defaults, so we know where we are)
- W1 (lots of messages from the modem)
- &C1&D2 (for hardware flow control)
- %C2 (enable V42 bis but not MNP5)
-
-
- 12.12 Zyxel
- ===========
-
- From one of our users again:
-
- The following "dial_cmd" is for a Zyxel U-1496E+ modem
-
- "ATL2N1X7&G2*E1DT"
- L2 --- sets a low (but not inaudible) speaker volume
- N1 --- sets a low (but not inaudible) ringing volume
- X7 --- sets result code options so that the "connect" message
- is, for example, "CONNECT 14400/Arq/V42b"
- &G2 -- enables 1800 Hz guard tone
- *E1 -- terminate call if error control negotiation fails, ie.
- insist on error-control or end call
- DT --- dial using DTMF tones
-
-
- 13. Testing
- ===========
-
- To test out your setup you could try using ping. ping
- gate.demon.co.uk whilst logged on directly to gate should
- return a speed of about 270ms on a fast link down to 1000ms on
- a slow link.
-
- Try using ftp to ftp.demon.co.uk and downloading files from
- /pub/test. There are files of varying contents that have also
- been compressed in various ways. "empty" files are there so
- that you can test the maximum throughput on blank data. "full"
- files contain a thorough mix of characters and so little
- compression by your modem will be possible. "regular" files are
- a mixture - just like this document or a Usenet news message.
- Each of these three have been compressed using popular methods
- and so you can try working on the compressed files as well if
- you like. Try uploading these files to
- ftp.demon.co.uk:/incoming to test the link in that direction as
- well.
-
- Using a V.32bis modem, the maximum throughput you are likely to
- get on a binary file is 1,600 cps. On an ASCII file the
- maximum is about 2,800 cps.
-
-
- 14. Finally
- ===========
-
- Please try to sort out your setup by following the above
- advice. If you are still stuck then telephone the support line
- on 081-343 3881 during support hours to see if further help can
- be offered. Full support line details are available in
- /pub/doc/Welcome.txt.
-