The monitor on your computer was probably specially designed for your computer. When you dial who-knows-where over the phone, you can easily be talking to some computer with a com-pletely different screen design than your own. Con-sequently, certain standards (rules of behavior for monitors to follow) have been devised. If you call up a hundred different computers, there will be many differences between the characters each can display, the control codes used to perform various screen functions, and so on. Your communications program, or "comm program," should be able to adjust to a wide range of these codes and charac-ters. This feature is known as terminal emulation. Software that can't do that will often represent data
from the remote computer in peculiar ways, or as garbage characters. Your comm program must be able to emulate a good number of terminals, such as ANSI, VT52 and VTIOO. It is also handy for the software to have a translation table - the ability to translate incoming and outgoing characters to other characters.
The terminal program you choose should be able to send and receive files using the Xmodern, Ymodem, Zmodern, and Kermit protocols. A proto-col is a set of rules. You see, if you're "ing to move files between two completely dissimilar computers, those machines need to know how to talk to each other. These file transfer protocols set up specific guidelines for the two computers to follow regard-ing how the file should be sent and received. Each protocol has its own set of advantages and applica-tions. The Zmodem protocol transfers files fast, and with good error recovery, but it isn't as prevalent as the original Xmodem. Ymodem is another improvement on Xmodern, but its error detection isn't as keen - only use it on clean phone lines. Kermit is used on many university mainframes for speedy, efficient file transfer. Make sure your terminal software has at least these four protocols. Choose software that allows you to enter "AT" commands. ATtention commands were developed by Hayes to allow the user to control the modem. They have been
adopted for most makes of modern. AT commands allow you to program the modem to dial, go on line, go off line, and perform various other functions. You should also be able to shell to your computer's operating system while maintaining the connection - sometimes you will want to run another program while on-line. The software should allow you to be able to store many phone numbers, names, and comments for a large number of dialups. You should be able to store more than just the ten digit phone number extensions and special codes should be pro-grammable, as well as sign-on macros for faster connections. It is also helpful to have auto-dial capacity, which repeatedly calls a busy phone num-ber until the line is free. Overall, the program you use must be pleasant and easy to use. If one program doesn't
suit all your needs keep several on hand and use whichever you need when you need its special services. Generally I tend to stick with the PC Tools Desktop comm program. It doesn't have too many advanced features, but its ease of use more than makes up for that. ProComm Plus for the IBM and Macintosh is the Lotus 1-2-3 of communications, software. It's a huge package that includes every conceivable feature you'll ever need. There are also many low price (free) alternatives in the world of shareware and public domain software. QModem is one good shareware communication program for IBM computers.
There is one final necessity for the hacker:
