The manufacturer was a heavily indebted, four-person firm located between a massage parlor and a laundromat in a suburban shopping center outside Albuquerque.

The computer this obscure company produced was a plain rectangle of gray metal that came equipped with a microprocessor, a jury-rigged input/output circuit and a full 256 (not 256K, but 256) bytes of memory -- barely enough to store one short paragraph.

There was no operating system, no off-the-shelf software. Niceties like a keyboard and a monitor were still under development. To load in data, you flipped a bunch of switches on the front of the box. The answers came out in the form of a row of blinking red lights representing binary numbers.

It was all thoroughly primitive, and yet we can say without much doubt today that this antediluvian machine, the MITS Altair 8800, was one of the most important and most influential developments in the history of personal computing.

The coming of the Altair, in fact, marks the real beginning of personal computer history. It wasn't the first computer built just for personal use, but it was the first one of this new breed that caught on and demonstrated that a "personal computer" could be more than just a pastime for obsessed electronics hobbyists with solder in the blood.

This month the computer world is celebrating the anniversary of the Altair: The first units of that venerable trailblazer were shipped in February 1975 -- just 10 years ago.

Only 10 years? It's astonishing how much this prescient child has grown in a single decade.

Ten years after he finished his first telephone, Alexander Graham Bell was still traipsing around to trade shows trying to convince the world that this gimmick was real. Ten years after the first working television, the boob tube was found only in the homes of a few dozen electronics engineers.

But the personal computer, in the decade since Altair, has grown up precociously and become nearly ubiquitous.

From our present vantage point, it is hard to appreciate what a stunning break with the past Altair was.

In February 1975, the smallest computer on the market was a $35,000 mini that filled the better part of a small office. The folks at Digital Equipment had recently stunned the industry with a computer small enough to be jammed into the trunk of a large car -- if it was disassembled first.

Some visionaries at Digital and other places already were talking about a computer small enough and cheap enough to be bought by individuals and used on a desktop. But the person to make this dream a reality was a moonlighting Air Force officer in Albuquerque named Edward Roberts, who had founded a struggling electronics firm called Micro Instrumentation and Telemetry Systems.

Roberts worked up the design of his simplistic, 256-byte computer and shipped it off to Popular Electronics magazine. The editors loved it, splashing the machine all over the cover of their January 1975 edition ("PROJECT BREAKTHROUGH! World's First Minicomputer Kit to Rival Commercial Models . . . ").

Although the Altair could do almost nothing useful, orders poured in by the thousands. The list of buyers reads like a Who's Who of the computer world today. A couple of teen-agers named Paul Allen and Bill Gates, who were running a little computer firm called "Traf-O-Data," were enthralled by Altair and wrote a BASIC interpreter for the machine. When the program became a hot seller, they changed their corporate name to MicroSoft -- today the dominant force in software.

One of the first Altairs was displayed at a meeting of the "Homebrew Computer Club" in Palo Alto, Calif. Two club members looked it over, liked what they saw, and decided to build a similar machine of their own. When it was done, the two hackers, Stephen Wozniak and Steven Jobs, named their machine the "Apple I" and set out to see if they could sell the thing to anybody. Back in Albuquerque, Ed Roberts was making ambitious plans for peripheral gear -- a disk drive, a memory expansion to 4K bytes of RAM, a monitor and keyboard -- and for a new, more powerful personal computer.

But then a buyer came along and made Roberts a rich man overnight in return for the controlling stock in MITS. Without the founder's guiding spirit, the Altair fell far behind in the increasingly competitive world of microcomputers; by 1979, the Altair computer was dead.

When you think about all that has happened in the single decade since Altair was born, you realize how hopeless it is to try to predict what personal computers will be like by Altair's 20th birthday. We can guess with some confidence that the personal computer of 1995 will have completely different storage devices -- today's RAM chips and magnetic disk drives will be nothing more than memories. Software will be genuinely integrated and personalized to each individual user's needs. Computers will be so cheap that people will have separate machines for each task -- word processing, number crunching, networking, etc.

But what things will actually look like then is impossible to say. Probably the only safe prediction is that today's Macintosh and IBM-AT will look as antique and outmoded as the Altair does from our vantage point in 1985.