Compact discs, the medium that has all but rendered conventional audio records obsolete, is poised to make a major impact in the personal computer field as well.

CD-ROM, an acronym for compact disc read-only memory, is to computers what CD players are to the audio enthusiast. And the terms share much in common because they are based upon identical technology. With CD-ROMs, computer information is stored on a small disk in digital form, along groups of tiny pits and spaces molded into the surface of the disk. A laser beam is reflected off the irregular surface and into a sensor, which translates the light into pulses of electrical energy.

Computer electronics then translate the energy into the information that was originally stored.

With hard disks getting so cheap (a 10 megabyte one can be purchased now for $150), why bother with CD-ROMs?

It's a legitimate question until you attempt to store anything so large that it makes your typical spreadsheet and data base files pale by comparison. Hard disks are fine for storing 5,000-name mailing lists. But just try saving the text of a series of reference works on your hard disk. One CD-ROM can hold the equivalent of more than 1,500 floppy disks. The text of the entire Encyclopaedia Britannica, for example, could fit onto a single CD.

Another problem is, who's going to input all that data onto your hard disk? With CDs, once the masters have been stamped, thousands of CDs can be produced relatively inexpensively. These traits make CD-ROMs ideal for the storage of bibliographic information, reference works, legal citations and large financial data bases.

Such gee-whiz technology is nice to dream about, but when will it be available? The answer is now, and from a number of vendors.

CD-ROM disk drives that connect to your computer and work like a hard disk start in the $1,000 to $2,000 price range, and prices are quickly pushing down toward the $1,000 barrier. Even IBM has given its sanction to the emerging technology by introducing a CD-ROM disk drive for its PS/2 series of machines.

Microsoft has been active in the software area, hosting annual CD-ROM conferences in Seattle, where the latest products and promising technologies are shown. Microsoft also has provided software hooks that allow DOS to read CD-ROM drives as if they were the same as ordinary disk drives. More than 150 titles have been released in the past year, so there doesn't seem to be a shortage of software on CD-ROM.

You'll soon begin to see increasing amounts of CD-ROM technology used in PCs, for a simple reason. Manufacturers have made large investments in plants to produce CD players and disks for the audio world. These same plants can be used to turn out computer disk drives and CD-ROM software, with little retooling.

What I would love to see is a portable CD player that could connect to headphones (for audio), or to my PC (as an external disk drive). Perhaps some manufacturer out there is listening.