The CIA World Factbook 1992

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THE UNOFFICIAL, UNAUTHORIZED SUPPLEMENTARY PC PURSUIT HANDBOOK by David Nye As of this writing, Telenet has not issued a complete PC Pursuit handbook. After noticing that the same questions are being asked repeatedly on the Net Exchange (the official PC Pursuit BBS), I decided it might be fun and helpful to write a supplement to the pamphlet you got when you signed up entitled "How To Use Telenet's PC Pursuit Service". If you find errors or omissions, please let me know by leaving a message on the Net Exchange board and I will try to incorporate your suggestions in new editions. I am a hobbyist, in no way connected with Telenet (which leaves me free to say some things I might not be able to otherwise)! WHAT IS PC PURSUIT? PC Pursuit is a low-cost long-distance packet-switching service offered by Telenet. A packet-switching system is like timesharing a telephone line. First a packet of your characters are sent, then another user's, then another's. Since a telephone line can carry information at a much higher rate than most modems can send or receive, and since much of the time you are typing or reading what is on the screen, the slowdown is usually tolerable. Generally all you will notice is a slight delay between entering characters on the keyboard and their appearance on the screen. The packet- switching becomes much less transparent with file transfer protocols, particularly those which send data in small packets and wait for the other end to signal success before sending the next packet (more on this later). user 1 --\ <--(a) <--(b) <--(c) /--bbs a user 2 ---indial--------------------------outdial---bbs b user 3 --/ (1)--> (2)--> (3)--> \--bbs c Fig. 1 Packet switching Although the indial modems (what your computer's modem connects to at your local Telenet number) are widely distributed, the outdial modems (those that connect to the modem of the bulletin board you are calling) are limited to 25 (and counting) cities. Once you are connected to the indial modem, you send Telenet a command telling it which city you want to connect to, and it will try to find you a free outdial modem in that city. Connections to the indial and from the outdial modems are through standard local phone company lines. The packet-switching part only occurs between the indial and outdial modems. SO WHAT'S THE CATCH? Telenet can charge so little for PC Pursuit only because several users are sharing one line. In exchange for the slight slowdown this causes, you save big bucks over what you would have to pay Ma Bell (or whomever) for your own line. No one would use a packet-switching system if money were no object, but I have found the inconveniences well worth the price. Here are some of the major "catches": 1. Slower transmission of data. As mentioned above, this is minor for typing and reading messages, worse for transferring files. Some of the newer file transfer protocols allow 90+% efficiency, but older ones can take several times as long to transfer a file as compared to standard phone lines. Trouble is, not all boards or comm programs support the newer protocols. 2. Some cities are next to impossible to get into. Telenet is always in the process of adding more modems to these cities, although sometimes not as fast as you or I would like! It helps to call at less busy times (early evening or wee hours), call at 300 baud (although many of the 300 baud modems are now being converted over to 1200 baud, so 300 baud may not be available in all cities), or use script files to automate dialing, sign-on, downloading of messages or files, and signing off. Then just start the script file running and go to bed. It is essential to use a script file or some other means to automate the sending of the C DIAL command. If you have to type it yourself over and over again you will go crazy. Users have written some slick PC Pursuit script files for some of the more popular comm programs. Check the files section of the Net Exchange. 3. PC Pursuit doesn't go to the city/board you want. Them's the breaks. If you are considering signing up to access a specific board or boards, be sure to check the exchange list in the file section of the Net Exchange (or the 800 board at 1-800-835-3001) before committing yourself. If you just want access to the few thousand other boards PC Pursuit provides access to, you're in luck. 4. You can't get anyone at Telenet to answer your questions? They've always been pretty good when I've called, but hey, now you have the complete user's manual! The best place to get any unanswered questions answered is to leave a message on the Net Exchange board or on Doug Azzarito's board (log into 305 and then dial 1-627-6969). Doug seems to know more about PC Pursuit than almost anybody else, and is also keeper of the only complete PC Pursuit BBS list. HOW TO GET STARTED First read the pamphlet Telenet sent you when you signed up called "How to Use Telenet's PC Pursuit Service". Then dial your local Telenet number with your comm program set for 7E1 or preferably 8N1 bits/parity/stop bits. When it connects, type the appropriate character(s) from the table below: baud full duplex half duplex ---- ----------- ----------- 7E1 300 or 1200 <cr><cr> <cr>;<cr> 2400 @<cr> @;<cr> 8N1 300 or 1200 <cr>D<cr> <cr>H<cr> 2400 @D<cr> @H<cr> When asked for a terminal type, enter D1 for most PCs (see TERMINAL.TXT for other terminal types supported). Telenet should respond with the @ prompt. Now enter C PURSUIT,<id>,<password> (where <id> and <password> are your own id and password) to call up the Net Exchange, the official PC Pursuit BBS. Keep doing that until it responds CONNECTED. If you can't get in right away, consider writing a script file to automate reentering this command. Once on the Net Exchange BBS, follow the instructions to log on. Read through the messages. Leave one if you like (it's polite). Next, follow the instructions to get to the file section and download the exchange list. This tells you what local exchanges you can call from each city. Also get TIPS.TXT, a copy of an internal Telenet memo with answers to questions commonly asked the people who man the help line (some of the stuff is out of date). If there is a script file for your comm program in the library, you might want to download it also. Then sign off (enter G at the prompt). Try some other boards. Call Doug Azzarito's board (see the previous paragraph) for the "official" PC Pursuit BBS list. FILE TRANSFER PROBLEMS Binary file transfers go more slowly than text transfers mainly because of the associated error-detection activity. Protocols like XMODEM and Kermit send a block of data followed by a checksum or some other error-detection information, then wait for the other end to signal that it has received the block intact before sending the next. The block of data and the acknowledge each encounter delays inherent in a packet-switching system, slowing the transfer. Sending data in larger blocks will speed things up except on a noisy line, where the time needed to retransmit garbled blocks outweighs the savings. Timing constraints will cause problems with some protocols. Punter for Commodore systems is unusable over PC Pursuit for this reason. The sender, having not received an acknowledgement of the first block sent, thinks it got lost and has just started to send it again when it receives the original acknowledgement, and the program bombs. Standard XMODEM will work erratically, so you should use Relaxed XMODEM instead. YMODEM is not quite the same from system to system, so it can be flakey with some boards and comm systems and not with others, but it is significantly faster than XMODEM. The most efficient protocols are the "sliding window" ones, which send blocks of data continuously, listening at the same time for replies. Some newer implementations of Kermit support sliding windows, as do WXMODEM, ZMODEM, and SeaLink. These will run at near-normal speeds, depending on how clean the line is. ZMODEM is probably the best of these, but they all work well. One thing you should do for all file uploads is to enable the break to command mode feature using the SET? commands (see below). The default way to get back to the Telenet @ prompt is by entering <cr>@<cr>. Occasionally this character sequence may occur in a file you upload, aborting your upload and throwing you into command more. By typing <cr>@<cr> then SET? 1:0,7:8<cr> then CONT<cr> once logged into the target city but before dialing a board, you instruct Telenet to recognize a break signal (most comm programs can send one) instead of a @ to get back to command mode. If that still doesn't work, you can make it impossible to get back to command mode by entering 7:0 instead of 7:8, but you will then have to hang up and redial to get to another city. If your uploads (or downloads) are still not going smoothly after all of the above, try booting up your system without any TSRs (terminate and stay resident programs, for you non-MS-DOS users). Try uploading from a RAM disk. Try a different comm program or protocol. Make sure you are set at 8N1 (some comm programs will automatically switch you to 8N1 for binary file transfers). If you see lots of garbled characters when reading or sending text, you have a noisy line. If it occurs with all BBSs you try, it is between you and the local Telenet indial modem. Not too much you can do about that. You might try another modem to see if yours is flakey. I think you can even have the phone company come out and check your wiring or install special filters ($). You can often get a higher quality line by paying lots more ($$). You can almost always fix a problem with downloading some way or another, but there have been occasions where nothing I tried resulted in the successful uploading of a certain file to some board. TROUBLE REACHING A BBS If a BBS you're trying to reach is always busy, there are several possible causes. The first and most obvious is that it is, in fact, always busy. Since you've probably already signed off and direct dialed and it started ringing, let's consider the other possibilities. BUSY doesn't always mean busy. Telenet's modems when in the default Hayes-compatible mode will respond that way whenever they can't connect to a number for any reason. The two most likely problems in my experience are that the board lies outside PC Pursuit's reach (check the exchange list for that city) or has been taken down, in which case you are either getting "I'm sorry, but the number you have dialed ..." or some poor bastard who was given that number after the BBS operator relinquished it. Sysops, please, when you take a board down, suggest to the phone company that they retire the number so the latter problem can be avoided. Using a second command mode supported by most of the PC Pursuit outdial modems, you can find out a bit more about what is going on when Hayes mode reports BUSY. Type ATZ<cr> (all caps) then control E<cr> and you will be greeted with the cheery "HELLO:I'M READY" of Racal-Vadic mode. Next, type ?<cr> to see a menu of commands. The important ones are D to dial a number, R to redial, and I to get back to Hayes mode. After you dial a number, RV mode may tell you RING if it is ringing, NO DIAL TONE (meaning there is a problem with the outdial modem), FAILED CALL meaning nobody answered within ten rings, or NO ERROR CONTROL which you just ignore. The other possible responses have obvious meanings. If you get RINGING RINGING BUSY!, then the phone was probably answered by a human. The BBS may not live there anymore. RV mode will also return BUSY sooner than Hayes mode if the board is actually busy, so I use it if I am trying lots of different numbers, say in a new city I haven't called before. Be sure to enter 'I' at the * prompt after you are done to return the modem to Hayes mode before you sign off, or the next caller will be greeted with MANUAL ANSWER in response to typing ATZ. If this happens to you, you have stumbled into RV mode. Use 'I' to get out. Read Jack Radigan's excellent RVPRIMER (included in this package) for more information. THE SET? COMMANDS These commands allow you to change some of Telenet's default communication parameters. They should be entered once you have gotten into the desired city but before dialing a board. After you have connected to the target city, enter <cr>@<cr> to get into the command mode, the SET? command, then CONT<cr> to return from command mode so you can dial your board. The SET? commands affect your end of the Telenet link. You can use RST? instead of SET? to similarly change options at the other end. You don't NEED to know anything about these to use PC Pursuit, but if you're someone like me who wants to know all the little details, and perhaps tweak a percent or two iprovement out of PC Pursuit, read SET_ITI.TXT, TELE_ITI.TXT, and X3_ITI.TXT. BUT WHAT ABOUT . . . Well, that is enough for a start. I'm open to suggestions for what else I should include here. Dave Purks, the Net Exchange sysop, told me after I sent this to his board that he is working on a more complete manual for PC Pursuit. The various supplemental .TXT files included in this package are his, except for RVPRIMER.TXT which Jack Radigan wrote. David Nye P.S. Don't send me any money. I did this for fun. If you want to express your gratitude, write the FCC and tell them you oppose access charges for enhanced service providers (see the files on this on the Net Exchange). If they eventually have their way, PC Pursuit will be just a memory!