Hooking up your computer to the world, or at least to an online service, means making choices and, inevitably, compromises.
At the extremes, Compuserve is huge, but it is all too easy to rack up hefty bills. Prodigy is relatively small and inexpensive, but does not offer the full range of services an enthusiast expects.
America Online falls between.
It is certainly easy enough to get started. Put the installation floppy disk into the drive of most DOS computers, Macintoshes or Apple II's equipped with a modem, type a word, and it guides you the rest of the way.
In most parts of the country, you can select a local or nearby telephone number, avoiding running up a big phone bill.
Next you fill in a form on the screen, including that vital piece of information, a Visa or Mastercard or checking account transit number, and in a few moments you are welcomed on line.
You have to go through this process only once. In subsequent sessions, you type a command, click a button and enter a password.
Now it is time to browse. There are eight departments: Computing and Software; News and Finance; Learning and Reference; Travel and Shopping; What's New and Online Support; People Connection; Lifestyles and Interests, and Games and Entertainment.
Travel and Shopping, for example, offers the Easy Sabre airline service, travel news from USA Today and foreign exchange rates.
There are also classified advertisements, and you can buy computer hardware and software, send flowers or have your documents printed out by a laser printing service.
One of the attractions of online services is meeting new people, even if you never encounter them in the flesh.
To this end, you are encouraged to write a profile of yourself and your interests and enter it into the directory of members.
Of course, in this kind of communications, baby blue eyes are irrelevant, but a passion for stamp collecting, hang-gliding or travel may lead to electronic friendships.
America Online costs $7.95 a month, which includes two free hours, plus 10 cents a minute when used beyond that.
Sign-up kits are free; to order one call (800) 827-6364. For more information, write America Online, 8619 Westwood Center Drive, Vienna, Va., 22182, or telephone (703) 448-8700.
Students and teachers, writers on science and even practitioners of it often turn for help to the "McGraw-Hill Concise Encyclopedia of Science and Technology" and its companion volume, the "McGraw-Hill Dictionary of Scientific and Technical Terms."
The books have been on CD-ROM disk since 1987, and now there is an updated and improved version, Release 2.0.
The new release contains the complete texts of the second edition of the encyclopedia and the fourth edition of the dictionary -- about 7,700 articles and 117,000 terms and definitions -- along with all of the illustrations from the encyclopedia, 1,700 photographs, line drawings, formulas and representations of chemical structures.
It is much easier to find things on a disk than in a book; keywords are linked and it is possible, for example, to look up an unfamiliar word in the dictionary while reading an article in the encyclopedia.
There are also more conventional tables of contents, one arranged alphabetically, the other by topic. And for those who are not sure exactly what they are looking for, the first screen presented is the Mirror of the Cosmos, a colorful Renaissance-style rendering of fields of knowledge on a series of circles within circles.
The Reference Set requires, at a minimum, a PC with a 286 CPU, a megabyte of expanded memory, a hard disk with two megabytes of available space and a CD-ROM drive (ISO 9660 compatible with Microsoft Extensions).
Optional, but desirable, are a Microsoft compatible mouse or trackball, a VGA display and an HP Laserjet printer or one that can emulate it.
The McGraw-Hill Science and Technical Reference Set, Release 2.0, has a suggested list price of $495. It is available at many CD-ROM vendors, as well as directly from the publisher by calling (800) 262-4729.
Owners of the previous version should phone (800) 842-3075 for special upgrade prices.