The Online World Part 42

ATDP9W4737031378

Register your standard dialing command in Procomm's MODEM SETUP.

Enter ALT+S and then select 1, Modem Setup. Choice 2, Dialing command. The default entry is ATDT. Replace this with ATDT0W, ATDP9W or whatever makes dialing work for you.

No answer from the remote computer ---------------------------------- Your computer has to "talk the same language" as the remote host.

If the parameters of your communications program have been set incorrectly, it may be impossible to set up a connection with the service.

Sometimes, you get CONNECT, but your screen only gives you strange, unintelligible 'noise' characters. The reason may be CONNECT at an incompatible speed, a service's use of special codes for displaying text (including special language characters), or that the service requires use of a special communications program or method (as when a service starts by interrogating for the use of an offline reader).

Many online services require that you use certain settings.

Most services, however, may be reached when using the following:

Speed: 2400 bps 8 bits word length, no parity, one stop bit

Some services (notably some Unix hosts) demand 7 bits, even parity, one stop bit.

Sorry, no luck!

--------------- Try again, just in case. The remote computer may have had a temporary problem, when you called. The PTT may have given you a particularly noisy telephone line on this attempt.

If this doesn't help, recheck each point in the communications process. It is so easy to do something wrong.

If nothing helps, read the service's user information manuals.

Only rarely will you be able to blame the communications program (unless you have made it yourself), or the equipment. Most errors are caused by finger trouble and misunderstandings.

Testing the Saltrod Horror Show ------------------------------- First time visitors often experience problems, and in particular if this is their first time online using a Hayes-compatible modem.

Here are some typical problems with suggested solutions:

* Disable Guard Tones from the modem when dialing. If it has this feature, you can often turn it off. Put the required command in your Modem init string.

* Don't press ENTER to "wake" my system. The software will automatically detect your speed and adjust accordingly. The same applies for many services. On some, you're just asking for problems by not waiting patiently (often the case when the remote software starts by checking if you use an offline reader).

* My BBS accepts from 300 to 9600 bps asynchronous, full duplex communication. You may not succeed with 1200 bps half duplex, Bell 300 bps or 1200 bps.

* Start with your communications program set for 8 bits word length, no parity and one stop bit. Try 7 bits, even parity if there is too much noise on the line (you cannot retrieve programs using this setting, though).

* When your modem is set at a low transfer speed, it may not wait long enough for carrier from my modem. Most modems let you set this waiting time longer by giving a value to a S-register.

(Read in your modem's manual about how to do this).

Partial success --------------- Some bulletin boards offer colors and music. If your equipment is set up correctly, you can receive the welcome text in full color graphics accompanied by a melody in your computer's speaker.

If it is not, chances are that you will get many strange codes on your screen, and an ugly feeling that something is wrong.

There are two ways out of this problem: 1. Ask the bulletin board to send text only (select U for Utilities, and then G for Graphics to change setting), 2. Set your computer for colors and graphics. This feature is only available for callers with an MS-DOS computers. You may need to add the line DEVICE=ANSI.SYS in your CONFIG.SYS.

Finally, you must have a communications program that allows you to display colors on your screen. Procomm set with ANSI-BBS does that.

Downloading programs -------------------- We call the transfer of programs and files from a remote computer for downloading. It means "transfer of data to your computer AND storage of the data (down) on YOUR local disk."

You are downloading, when you call my board to retrieve a program.

When you, overwhelmed by grat.i.tude, send one of your favorite programs TO my bulletin board, then we call it uploading.

Data can be many things. It may be news from Washington Post, a digital picture, an executable program, a pile of invoices, a piece of music, a voice file, an animated sequence of pictures and music, or compressed library files.

Downloading "plain text" (also called "plain ASCII" or "DOS text" on MS-DOS machines) is relatively easy. Such text usually only contains characters between number 32 (s.p.a.ce character) and 126 (the ~ character) in the ASCII table.

Characters with lower numbers have special functions (like the control characters ESCape and CTRL+C). These may not even be displayed on your screen. Characters with higher numbers are used for graphics, special national characters, and other applications.

Special transfer methods are often required, when your data contains text with characters outside ASCII number 32 through 126.

Read under "Protocol transfers" below for more information about how to do this.

Downloading text ---------------- Most communication programs require that you begin by opening a file. They ask you to enter a file name. From this point and onwards all incoming text will be stored in this file until you say stop.

Communication programs do this in different ways. Some let incoming data flow through a temporary storage area using the principle first in, first out. When you open a file, it starts storing data from the beginning of the temporary storage area, though this text may have scrolled off your screen some time ago.

Most communication programs start storing data from NOW.

Procomm works this way. You start downloading of text by pressing the PgDn key. A window will appear on your screen giving you a choice between various methods. Select ASCII.

In another window, you are asked to enter a file name. When done, storage of incoming data starts. You stop the process by pressing the ESC key.

Procomm has another method called "file logging." You start this by pressing ALT-F1. Procomm requests the file name, and the storage process starts. (Read under "Strip" about the difference between these methods.)

If you forget to tell Procomm to store incoming data, then you will most probably lose this data for ever.

Do not waste time and money by forgetting to store what you receive!

The term "append"

----------------- When downloading text - or anything - it is important to know whether you are appending information to an existing file, or overwriting it (i.e., destroying the old text).

Most communication programs complain with an audible signal, when you try to overwrite an existing file. They will ask you if you really want to delete it, or append the current data.

The term "strip"

---------------- The purpose of 'strip' is to remove something from incoming data or to change it on the fly.

When you use ASCII downloading with Procomm, ALL incoming data are being stored. This includes so-called ESCape sequences. If you use File Logging, all control characters (except the line feed and new page characters) are being removed (filtered).

If you download text from a computer that uses other ASCII characters for linefeed and return, save time by having the communications program convert them on the fly to their correct form for your computer.

You define strip procedures through Procomm's SetUp menu (ALT- S). You can also request automatic conversion of characters to graphics values, or local language variants.

National characters ------------------- Special national characters cause problems in many countries. One reason is that they are represented by different internal codes on various hardware platforms, and that some networks are unable to transmit 8-bits data.

Some systems represent these special characters by a 7-bit code, others by an 8-bit code. Some depend on the computer having an internal national language ROM, or that it uses a special (resident) conversion program.

What gives good results on an MS-DOS computer, may give rubbish on a Macintosh, Amiga, Atari, or a PC using MS Windows.

Many communication programs have features that can help you solve at least some these problems. They let you make translation tables for automatic conversion of special incoming and outgoing characters.

If you call a Scandinavian online service using 7 bits even parity, many transfer the national special characters using the ASCII code equivalents of number 91, 92, 93, 123, 124, and 125.

Similar, more or less formal standards are in place in other countries.

Protocol transfers ------------------ If your purpose is to transfer digitized pictures, a computer program, a batch of invoices, a piece of music or an animated sequence of pictures, it's important that each character (bit) arrives correctly. We achieve this by using protocol transfers.

These files often contain control or binary characters. You cannot transfer binary files without the use of special methods.

It is easy to understand why we need protocol transfers when retrieving plain text as tables of numbers, statistics, and financial reports. Transfer errors may have fatal consequences.

Protocol transfers are also required when transferring word processor text files having imbedded control codes (like text made with WordPerfect), and compressed files.

Here is an example:

Downloading public domain software ---------------------------------- First, you need the names and features of the programs that can be downloaded from a service. On most bulletin boards, you must enter a command to navigate to the File Library. Here, they normally greet you with a menu listing available commands.

Try H (for Help!) or ? when you are stuck.

Public domain and shareware programs are stored in subdirectories on my bulletin board. The directories have numerical names. Utility programs for MS-DOS computers are stored in directory 10. Games are stored in directory 17.

Enter L for a list of available directories (other bulletin boards may use different commands). Enter "L 17" to list the files in directory 17. This will give file names, lengths in characters (to help you estimate download time), creation dates, and a short description of each file.

You can search for files of interest. When looking for programs that can help you get more out of a printer, you may search using keywords like "printer."

Some programs are made available in text form. This is the case with older BASIC programs. (The file name extensions .BAS, .ASC or .TXT suggest that the files contain plain text.) You can download these files using ASCII.

Most programs are stored in their executable form, or as one executable file among several in a compressed transfer file (a library of files). On my board, most of these files have the file name extension .EXE or .COM.

What transfer protocol to use, depends on what is available in your communications program.

The protocol transfer method explained -------------------------------------- The protocol transfer algorithms use methods to check the transfer with automatic error correction. In principle, they work like this: The sending program calculates a check sum based on the contents of the file. The receiving program does the same calculation and compares the result with the senders' check sum. If the figures match, the transfer was successful. If not, all or part of the file will be retransmitted.

These are some popular protocols:

XMODEM ------ has automatic error detection and correction. Most modern programs have this feature. XMODEM exists in programs for MS-DOS computers, CP/M computers, Apple, TRS-80 Model 100, etc. It is the most commonly used transfer protocol.

XMODEM a.s.sumes 8-bit settings in your communications program.

The file to be sent is split up into 128 bit sized blocks (or "packets") before transfer. The sender calculates the check sum and adds a check sum bit at the end of each packet. (Packing, sending and checking is done automatically by the software.) The receiving program calculates its own check sum and compares with the sender's. If an error is detected, XMODEM will request retransmission of the last block.

XMODEM is reasonably good when there is little noise on the telephone line is low. When the line is bad, however, there is always a chance that the transfer will stop. You cannot use XMODEM on computer networks that use ASCII flow control or ESCape codes.

The transfer commands must be given to both computers. You can only transfer one file per command.

XMODEM's "packet size" (block length) is short. This has an impact on transfer speed, and especially when downloading from timesharing systems, packet switched networks, via satellites, and when using buffered (error correcting) modems.

The control method (8-bit check sum) and unprotected transactions give a low level of safety against errors in the transmission. The transferred file may contain 127 bytes with noise characters (at the end). The creation date of the file is lost in the transfer.