Tapping into an electronic bulletin board.
As microcomputer hardware and software proliferate, the babble of computer languages creates a 20th-century difficulty: communicating with people using micro-computer systems or software other than one's own. Sitting alone before the screen, working on a program and wishing it weren't continually necessary to reinvent the wheel, the laboratory micro user may long for a professional conversation. Here's a typical quandary:
"I'm developing new DNA probe procedures for our lab. I wish I could discuss the process with other lab people who have already done the same thing."
This wish and many others can be fulfilled with an electronic bulletin board system (BBS)--a centralized computer service. BBSes allow users in far-flung geographic areas and using different brands of software to share ideas and programs with each other. A Delaware physician who keeps tabs on BBSes around the world lists well over 200 medically oriented ones in the U.S. and a couple of dozen outside the country. One specializes in selling and trading used equipment.
Most BBSes provide two main types of service. The first is message areas, representing newfangled old-fashioned bulletin boards on which users exchange messages. The second is file areas, from which files and programs of many kinds can be obtained.
[P]The message area. To simplify access to their extensive bulletin board subcategories, most BBS menus divide their offerings into message areas concentrating on specific subjects. On Med TechNet, the seven-day, 24-hour BBS operated by the department of medical technology at the State University of New York at Buffalo, about 40 different areas are available. Message areas in Med TechNet range from topics in clinical laboratory and general medicine to technical support for WordPerfect software and for PCs in general. Med TechNet will serve as the running example in this article and will be described in this column in greater detail next month.
[P]The file area. The file area represents a collection of related files, including individual programs and information in ASCII (universally readable) format, such as a list of other medically oriented BBSes with their phone numbers and hours of operation. The approximately 14 file areas on Med TechNet include IBM PC and BASIC programming utilities; about 50 files of clinical interest, including health newsletters, QC programs, and statistical analyses; and the resume file area, in which resumes can be posted in open or encrypted form. For the latter, the person posting the resume must provide a simple encryption key before the file is fully readable. * Equipment. To work with a BBS, you need a personal computer; a modem; a communications program, such as ProComm, Telix, Kermit, or CrossTalk; and a standard voice-grade (not necessarily the more expensive computer-grade) telephone line.
[P]The computer. Virtually any type of computer may be used to access Med TechNet, including IBM and IBM clones, Apple, and Commodore. The PC must have a serial port, to accommodate a modem, and a communications package (also called a communications program), which allows the computer to communicate with the modem via the serial port.
Although any computer or simple video terminal may be used to contact Med TechNet and participate in the message areas, obtaining permanent copies of files from the file areas requires a micro-computer, for its memory, and a floppy disk or other mass storage device, such as a hard drive, for its ability to store the file for future use.
[P]The modem. Modems send and receive computer data over phone lines. Med TechNet automatically adjusts to transmission rates of 300 to 2,400 baud (see "Baud basics"). It can also handle 9,600 baud or more with US-Robotics HST modems, which are highly popular with BBS operators but more expensive than most people need ($1,000 or more at list price, about $600 at a discount). Although other brands have 9,600 baud capability, one brand usually cannot communicate with another. Currently, 2,400 baud is considered standard, primarily because its transmission speed is reasonably fast and its cost is reasonably low (about $125 at a discount, $300 at list for top of the line).
Modems come in two types: internal and external. Since an internal modem is plugged directly into an expansion slot in the PC, it does not require a serial port; an external modem needs one. The additional $10 to $20 for the external type add flexibility, permitting the modem to be easily moved from one system to another and for servicing.
A modem's command set incorporates the codes that enable the device to perform various critical functions--dialing, hanging up, and speaker volume, for example. Modems that emulate commands first introduced by Hayes, a pioneer of modem technology, are said to be "Hayes compatible" or "to have an AT command set," since all Hayes commands are prefaced by "AT."
The many communications programs on the market range from the simple, such as terminal emulation packages that allow a micro to act as a basic terminal, to the highly sophisticated, including systems that contain automatic telephone dialing directories, "hot keys" (individual keys programmed to do complex series of functions automatically), and various script languages that automate telecommunications.
A laboratory hacker asks: "We would like a program to automate data analysis for our microplate reader, but the programs are so expensive. Is there an alternative?"
Yes: shareware. Shareware is any software that users may try at no charge but for which they are asked to pay a nominal fee, typically $5 to $20, if they continue to use it later. Many shareware programs are of a quality at least as high as that of commercial packages. * The telephone line. A standard voice-grade phone line enables BBS communications to take place. Over a short distance, the quality of the phone line is not critical for good transmission. For long-distance calls, however, it is important to use a line offering high quality. Some are less suitable than others for data transmission. Many BBS users have found AT & T lines to offer consistent high quality at a reasonable cost. * File transfer protocols. Pulling a file into your computer from a BBS (or from any other source) is called downloading; sending a file from your system to another system is uploading. Once you have downloaded a file, it's yours. You can run it at any time, whether you are on-line with a BBS or not.
Before downloading a file, you must choose a file transfer protocol--that is, a procedure for transferring files between systems. What's important is not which protocol is used but that both the sending and the receiving computers use the same one.
The exchange is called handshaking, meaning that the two computers "agree" to send certain signals back and forth in a systematic way. Typically, the system from which a file is about to be sent sends a message describing what's coming and waits for the receiving system to indicate that it is ready to receive. The sender then begins to transmit.
Characters (bytes) are sent in groups, called packets, of a size predetermined by the protocol used. After sending each packet, the sender waits for confirmation from the receiving system. If the packet has arrived intact, a message tells the sender to continue. If not, the sender is instructed to send the previous one again.
File transfer protocols--for example, XMODEM, YMODEM, ZMODEM, Kermit (from Columbia University, popular with users of mainframe computers, especially in academic settings), and SEAlink (System Enhancement Associates, Wayne, N.J.)--differ in packet size, frequency of handshaking exchanges required, adaptability to telephone line conditions, and error detection/correction techniques. XMODEM--an early protocol that virtually every BBS and communications program supports--is slow and prone to error, among other draw-backs. One of the more sophisticated protocols in use today is ZMODEM, which works exceptionally fast and has an error correction feature, so that even a huge transfer won't be wholly lost if interrupted.
Since the modem determines the baud rate, and therefore the speed of transmission, how can one transfer protocol be faster than another? The variable is the efficiency of transfer. Not only the data transmission itself but also the frequency of handshaking required varies considerably.
A simple analogy will illustrate this concept. Suppose you want to count to 100 to a friend on the phone. If you used XMODEM or a similar protocol, you would count 1-2-3-4-5-6-7-8-9-10, then stop and wait for the other person to say, "Yes, I heard all 10 numbers correctly." Additional acknowledgments would interrupt the proceedings after every 10 numbers. With ZMODEM or a similar protocol, you would count directly from 1 to 100, being interrupted only when the protocol detected an error. Using the faster system to transfer a document consisting of hundreds of thousands of bytes would save a considerable amount of time. On a long-distance call, it would also save money. * File compression (archives). Transferring files can be extremely time consuming. A handy technique to remedy this problem is archiving, in which one or more files are compressed into a single file, called an archive. The degree of compression depends on the type of file being archived and the compression method used. In general, program files--identificable by the endings of their file names: .EXE or .COM--can be decreased in size by about 20 to 30 per cent; text files, by 50 to 70 percent; and other files, such as spreadsheets, by as much as 90 per cent. Imagine storing a 100K file as a 10K file!
One of the first popular archiving programs was ARC.EXE (System Enhancement Associates, Wayne, N.J.). Others quickly followed. Developers, largely independent programmers, are currently competing to create archives that provide the greatest degree of compression in the least amount of time. All these utilities are either on shareware or have been released into the public domain and are therefore available free of charge. File names ending with .ARC, .ZIP, .PAK, .LZH, and .ZOO are examples of archives. Archives commonly contain a program, documentation, and other support files.
File compression, highly popular for sending files over phone lines quickly, is equally useful for freeing space on a hard drive (by archiving seldom-used files) and for packing more information onto individual floppy disks. * Fighting fragmentation. "The hard disk in my two-year-old PC seems to take forever to load and save files; it seemed faster when it was new. Is that possible?"
It certainly is. The usual reason for a gradually slowed response by a hard drive is a process called fragmentation. Over time, information in MS-DOS and PC-DOS stored on a disk is broken up; the computer places the pieces wherever they fit on the disk. It then takes longer to load the program from disk to memory. Several commercial and shareware utilities are available to defragment disks, including one from Med TechNet, to be discussed in more detail next month. * Across the miles. "I live in Florida and use WordPerfect on an IBM PC. I'm working on a project with a colleague in Chicago who uses WordPerfect on her Apple. Exchanging files is an expensive nightmare on our tight deadline. We actually use an overnight delivery service!"
Sorry, Pony Express and Federal Express--BBS to the rescue. BBSes are format insensitive; that is, they serve as a central data depot for many different computer systems. A pathologist in Arizona, for example, can use an Apple to upload a program or document, which is then immediately available to a medical technologist using an Epson in Ohio. Even international communication is possible on BBSes that offer direct electronic mail (E-Mail)--and many, though not all, do. Med TechNet is connected with 4,000 other BBSes around the world.
One caution: Interchangeability can go only so far. It does not enable programs designed for one type of machine to run on another. The facility of BBSes to transfer files between machines quickly has made it easy--and increasingly common--for groups of people separated by many miles to collaborate, even on projects with a short lead time.