TOKYO -- "It's kind of surprising at first," said Microsoft's head honcho, Bill Gates, one of several top-ranking U.S. computer executives who came here for a computer trade show recently. "Because the technology for multimedia has really gone further in America. But the fact is, there is much, much more interest in this stuff in Japan. These companies are putting a lot of money into multimedia because they can see it is the future."

Before we can assess whether multimedia is the future of personal computing, we'd better slip back to the present and talk about what multimedia is.

"Multimedia" is a buzzword in the computer trade that refers to computer applications combining several different methods of presenting information. A typical multimedia program will involve TV (either live or prerecorded), music, spoken words, still photos and screens full of written text or charts. All this is controlled from the keyboard of a personal computer.

One famous example that is on the market now is the amazing program called "Beethoven Symphony No. 9" (The Voyager Co.), which runs on any Macintosh as a Hypercard stack. The program is a package containing the Mac software plus an audio compact disc of the symphony and a CD-ROM disk containing lots of information.

The program lets you listen to any measure of the 68-minute symphony while watching the score scroll past on the screen. If you want to hear the famous orchestral prelude to the choral part in the fourth movement, you click the Mac's mouse a couple of times and the measures you've chosen play while the music appears on the screen.

But that's just the start of it. If you ask for information about Beethoven's life or his place in music history, the program quickly serves up a biography, complete with maps and pictures. If you click the mouse on "The Art of Listening," the program provides further information. Whenever it refers to a musical example to make its point, it cues the audio CD and you hear the example.

A simpler multimedia product from the MS-DOS world is the children's game-and-education software called "Mixed-Up Mother Goose" (Sierra On-Line). The program is run from a standard PC, but the display is on a high-resolution screen and sound comes from a pair of stereo speakers.

In this program, cartoon characters act out various Mother Goose rhymes, first in English and then in foreign languages. The computer user -- presumably your child -- can shake up the plot lines by ordering Humpty Dumpty, for example, to run up the hill with Jack and Jill. All this takes place in cartoon-like animation on the big screen in response to your commands, with the sound played through speakers attached to the PC.

This concept of a computer-TV-stereo-text combination, using a computer to control information on several types of media, has obvious applications in education and training. Indeed, most of the software on display at the show here was for educational use.

Multimedia will almost surely have countless other useful applications. But, there hasn't been much development of multimedia software because few users have enough hardware to handle it.

As more and more people obtain the necessary hardware -- particularly the CD-ROM reader and CD audio player, both quite expensive today -- more of them will be looking for multimedia software. "Gradually," Gates said, "we will get to the critical mass where pretty much everybody has multimedia capacity in hardware."

The Microsoft founder has a stake in this, of course, because multimedia opens a new world of software for Gates to sell. A multimedia version of Windows, the smash hit "operating environment" Microsoft sells for DOS machines, is due next year. By the end of 1991, Gates said, there should be about 100 Windows-compatible multimedia software titles on the market, mostly in the education category.

Meanwhile, development continues on the Macintosh side. Apple's current Hypercard software provides an excellent format for controlling multimedia devices, and that has spurred software writers. Accordingly, multimedia is further along on Macs than on DOS machines so far.

One prototype program on display was a kind of cinema library, with hundreds of movies included in CD-ROM. If you ask the program to show you, for example, all the movie love scenes that have the Eiffel Tower in the background, the software begins searching and then the various movies start playing on the TV screen, while explanatory text and charts appear on the Mac's display screen.

Back to the basic question, then: Is multimedia the future of personal computing? It sure looks as if the answer is yes, but that future may be far off unless reasonably priced CD-ROM players become widely available.