In the world of personal computers for business --a world, despite Apple's best efforts, that consists almost entirely of the IBM-PC and its clones -- you really won't find a much better computer today than the Zenith Z-150.

In this space last week, as loyal readers may remember, I set forth the frustrations I encountered in building a personal computer from a kit -- a kit supplied by Heathkit Co. (Benton Harbor, Mich. 49022). But that sad story had a happy ending. When the kit was finally finished, I had a great computer: the Heathkit H-151, the kit version of the Zenith Z-150 (this is possible because Heathkit is a subsidiary of Zenith).

The Zenith/Heathkit entry in the IBM-compatible sweepstakes is a winner because it has followed closely the pattern set by the most successful maker of IBM-aping personal computers, Compaq. Like the Compaq line, Zenith offers its MS-DOS computer in both desktop (the Z-150) and portable (Z-160) models. Like Compaq, Zenith keeps its prices a little below IBM's, and it responds to IBM price cuts with comparable cuts.

Like Compaq, the Zenith offers so-called "100 percent compatibility" with the IBM; the Zenith machine can read and write IBM disks and can run just about any software written for the IBM-PC with no need for adaptation or patching. In tests over the past month, my Z-150 had no trouble with two dozen examples of IBM software, including "acid test" programs such as Flight Simulator, Microsoft WORD and Frontrix -- software that many alleged "compatibles" can't handle. The Zenith also can take standard IBM peripherals and expansion boards without adaptation.

The only IBM program I couldn't get to run on the Zenith was IBM's BASIC, which needs the proprietary IBM read-only memory to operate. This problem is fairly easily solved by buying ($100) the GW-BASIC program, which Zenith, inexplicably, does not include with its computer.

Like Compaq, Zenith solves the text/graphics problem by providing as standard equipment a video board that will run both monochrome and color monitors. The Zenith video board also can run graphics software written for the IBM color monitor on a standard monochrome screen. This important feature means you can use a monochrome screen, and the high-resolution words and numbers it displays, and still run programs that would require a separate color/graphics display on the IBM and most other computers.

Like Compaq, Zenith makes its computers in the United States, which means you can buy one without incurring the wrath of this column. And like Compaq, Zenith seems to be a healthy company with a long future -- an important concern for anybody buying a personal computer in today's tumultuous market.

And yet, for my money, Zenith has done some things even better than Compaq and IBM.

For starters, Zenith was smart enough to provide a regular, Selectric-style keyboard, rather than blindly copying the bungled keyboard that IBM inexplicably provides with its PC and XT. Although the Zenith has a self-diagnostic routine that runs every time you turn it on, the designers have made it an extremely fast operation. Instead of the 40- to 60-second delay that IBM users put up with, the Zenith is ready to use about five seconds after it's turned on.

Zenith's prices tend to be about 5 to 10 percent lower than Compaq's, and Zenith periodically offers a small bundle of free business-oriented software (my H-151 came with Microsoft WORD and Multiplan) in the bargain. Reflecting its connection with Heathkit, which caters to serious computer buffs, the Zenith computer provides a number of useful functions and features that greatly enhance an advanced user's ability to make the most of the computer.

The MS-DOS manual that comes with the Zenith machine is by far the most complete and detailed MS-DOS book I've ever seen. It might overwhelm a beginner, but for power users it is a treasure. Zenith's version of MS-DOS includes a number of utilities not provided with the IBM-PC, including the ability to read disks written under the CP/M operating system.

Also provided is a utility that will create a RAMdisk in memory. This little bonus feature has two great assets. For one, it's provided free; IBM and many clones require that you go out and buy a separate RAMdisk program. Second, the Zenith program lets the user decide precisely where in memory the RAMdisk will reside. This is an enormous boon to those of us who use other memory-resident programs, such as SideKick and Maxam. The inclusion of this small feature, which I've never seen on any other RAMdisk software, reflects Zenith's admirable concern for the serious computer user.

To sum up my two columns on this subject, then, I would say that the Zenith Z-150 is a terrific IBM clone that I can recommend -- if you buy it fully assembled. Unless you're a glutton for confusion and frustration, I can't recommend buying the kit version of this computer, the Heathkit H-151, which you put together yourself.