What a difference a year makes. Personal computing has undergone fundamental change, which was apparent at this year's Comdex trade show in Las Vegas, where hardware and software manufacturers competed for the attention of dealers and writers.

At long last, in the IBM-compatible arena of computing we have some real standards that define the common level of hardware and software that business-oriented and many home computer systems will have.

They will be high-performance computers using the Intel 80386 microprocessor in either its low-cost SX variant or higher cost DX chips, equipped with at least 1 megabyte of RAM operating memory, and probably more, a hard disk drive and a color VGA monitor.

These computers will use the DOS operating system along with Microsoft's Windows 3.0 graphical user interface software and various software programs that run with Windows.

Less powerfully equipped computers will continue to be popular among the budget-conscious, of course, but the 386 color system with Windows has become the machine of choice because it achieves a much easier and richer level of computing than DOS computer users have been used to.

Last year at Comdex, Windows 3.0 was just a rumor, 386-based computers were still too expensive to proliferate, as was VGA color, and OS/2, not DOS, was being touted as the PC operating system of the future.

What changed?

For one, 386SX-based computer prices fell to where 80286 machines used to be. For another, color VGA board and monitor combinations fell to little more than we once paid for green-screen monochrome systems.

And Windows 3.0 was such an improvement over previous versions that software developers started focusing their efforts on programs for Windows instead of programs for OS/2.

Last year there was an acrimonious debate between IBM and Compaq engineers over which one of their internal system designs was best -- microchannel architecture (MCA) at IBM or extended industry standard architecture (EISA) at Compaq.

Guess what? Both are alive and doing well this year. Many manufacturers have followed Compaq's lead, offering their own EISA high-performance computers, and IBM's proprietary design MCA machines continue to sell well. The most sales of all are still enjoyed by the older design originated on the IBM PC/AT, which is known these days as ISA, for industry standard architecture. Another significant change was the way more than a dozen manufacturers introduced so-called notebook-sized computers that were more alike than different. The new notebook designs all use 386 chips, mostly the SX version; black-and-white VGA screens able to display 16 or 32 shades of gray; internal hard disks of at least 20 megabyte capacity and often 40 megabytes (or 60 megabytes); a 3.5-inch floppy drive for 1.44 megabyte diskettes; and an internal modem.

Keyboard layouts differed, as did screen contrasts and placement of the various drives and output ports, so buyers will want to shop carefully.

Something that remains expensive and thus not in wide use is optical disk drives that can rerecord data over and over again like magnetic disks. They are still a lot slower than magnetic drives, but the ability to store half a billion bytes or more on a single disk is a powerful incentive for use on network file servers.

In the software arena, William Gates, the founder and chairman of Microsoft, delivered the keynote address. He portrayed a world in which computer users need be concerned only with the words and numbers and images they want in their documents, not the programs needed to put them there. He predicted that such software technology will be available during the 1990s. But you can already buy software that achieves much of that goal for only $200 (probably less) at your neighborhood software store. It is called New Wave and is published by Hewlett-Packard. It runs with Windows 3.0.

Comdex is mostly a show for IBM-compatible computing. Apple had a booth and some Macintoshes were scattered here and there, but not many. Mac developers like to show their wares at Mac-only expositions.

For me, however, the hit of the show was neither PC- nor Mac-related. It was Video Toaster, a $1,595 board and companion software for an Amiga computer that turns it into a broadcast-quality video production machine with real-time image processing. I'll have more about it in a future column.

Richard O'Reilly is a Los Angeles Times staff writer. Readers' comments are welcomed, but the author cannot respond individually to letters. Write to Richard O'Reilly, Los Angeles Times, Times Mirror Square, Los Angeles, Calif. 90053.