A history of how the personal computer came to be; Fire in the Valley: The Making of the Personal Computer, by Paul Freiberger and Michael Swaine. Berkeley, Calif.: Osborne/McGraw-Hill. Paperback, 288 pp. $9.95.

Fred Guidry is a member of the Monitor's team of computer systems supervisors.

Although the personal computer industry is still very, very young, it is fitting that a quick and detailed history should already have been written about it.

From the intimate account provided by ''Fire in the Valley'' we get fresh evidence that a great new industry can start from humble beginnings. We knew this, of course, from the fairly recent examples of the automobile and the airplane. But to have such dramatic new proof can only be encouraging to those who see few opportunities for spectacular accomplishment in a mature industrial society.

In addition, we get useful glimpses from this book of the vital importance of good management. The true pioneers in the personal computer industry did not make fortunes. Almost without exception their little companies, started in so many garages and run-down old buildings, had brief lives. Taken one by one, the stories of companies like MITS, Processor Technology, and IMSAI should make useful case studies for business schools. They are classic examples of too little vision, or capital, or marketing know-how, or all of these - and more.

For all its serious intentions, both as to thoroughness and accuracy, and its agreeable writing style, this modest-size history is likely to appeal mostly to readers who have been immersed in personal computers all along. But the newcomer to the subject will surely learn a great deal, too, because events of the earliest years - the early 1970s - were generally covered only in electronic hobby magazines.

The authors have done a good job of explaining such computer elements as operating systems, high-level languages, and memory boards as they go along, without unduly slowing up knowledgeable readers. And there are helpful evaluations of events and personalities, which give even the newcomer a perspective at each stage of the industry's development.

''Fire in the Valley,'' though not an ideal book for popular tastes, may prove a landmark volume among secondary sources, to be used by authors of compelling and sweeping analyses still to come.