A book on MS-DOS, the most popular operating system for personal computers, would be a welcome gift for a friend or relative, but you do have to know a few things before you buy one.
First, and most important, is whether the recipient's computer runs DOS.
The personal computers made by the International Business Machines Corp., and all the machines compatible with them, are DOS machines. (To be quibbling, true-blue IBM computers use PC-DOS, rather than MS-DOS, but they amount to the same thing.)
Brand names are legion: Compaq, NEC, Dell, Gateway, Zeos, Leading Edge, and on and on. You can't tell from the name, unless it is IBM, whether the computer can use DOS, but you could always ask.
If the computer is a Macintosh, Amiga, Atari, Commodore 64 or Apple II, it does not ordinarily run DOS. You also should know whether the recipient of the gift has updated to version 5.0, the latest incarnation of the operating system.
There are innumerable books on the subject. A dozen sit on my bookshelf, and that is just a representative selection. Several good ones have been mentioned in this space in the last year; the following are newer ones.
Especially helpful for a beginner, although by no means to be scorned by experts, is "PC World DOS 5 Complete Handbook," by John Socha and Clint Hicks (IDG Books Worldwide; $29.95).
It starts with the most basic concepts, teaching through a special edition of the Norton Commander program, which is supplied on a disk with the book.
The pages are well illustrated with depictions of what you should see on the screen as you go through various operations.
The Norton Commander is just one of many "shells" -- programs that simplify DOS -- but both the authors formerly worked at Peter Norton Computing, so their bias is forgivable. In fact, Mr. Socha wrote the program that became the Commander.
If the reader is already an expert, or becomes one by working through the first half of this 600-page book, there is a feature that will remain useful for some time to come: detailed descriptions of virtually every command employed with DOS, from version 2 to version 5, that are much fuller and clearer than the ones in the official Microsoft manual.
The DOS 5 Handbook is a new book, starting at the beginning level. "Supercharging MS-DOS," by Van Wolverton and Dan Gookin (Microsoft Press; $24.95), is the third, revised edition of a classic for seasoned users.
This is for people who are not cowed by AINSI.SYS, DEBUG or the writing of customized menus.
As an example of the differences between the books, "Supercharging MS-DOS" devotes a chapter to DEBUG, the program that lets you change files right down at the level of individual bytes.
The reference section of "PC World DOS 5 Complete Handbook" mentions it only to warn that "this is a very advanced command that is almost always used by programmers," and not by ordinary people.
The truly computer-obsessed will revel in the 15th edition of "The Secret Guide to Computers," by Russ Walter, although not everyone will be charmed by a grown man who calls himself "Russy-poo."
Mr. Walter covers just about every subject in the microcomputer universe: buying and getting started with a system, whether DOS or Macintosh, and many of the standard applications and programming languages, not to mention history, gossip and personal advice.
In the unlikely event that you have a question his book doesn't answer, Mr. Walter gives his phone number and invites you to call any time, day or night. ("I'm almost always in and sleep lightly.")
If that's not enough, he also gives his address, in Somerville, next to Boston, and directions for how to get there by subway or car. ("Park on the left side of Ashland.")
Not in this edition, Mr. Walter pointed out in a telephone interview (Sunday afternoon, phone picked up on second ring), is MS-DOS 5.0. "We hope to get it in the next edition," he said; it will probably appear in March.
Aside from free computer help, Mr. Walter is a tutor. Details of his 20-hour weekend "blitz" course, as well as both private and group classes, come with his book. It is $15, and may be ordered from The Secret Guide to Computers, 22 Ashland St., Floor 2, Somerville, Mass. 02144. There are special rates for multiple orders.