More than ever, people are seeing the advantages of taking a computer with them everywhere except in the shower. The new breed of lap-top computers are getting smaller, lighter and more powerful. The Kaypro 2000, which costs about $2,000, comes standard with 256K, a built-in disk drive, full 80-by-24- line screen and tons of software. The Data General One costs $2,500, has a full-sized LCD screen and a built-in disk drive. The Zenith Z-171 has two disk drives and a full-sized screen that`s the easiest portable screen to read around ($2,699). The Quadram Datavue 25 has an infrared keyboard (no cable attaching the keyboard to the computer). All of these are IBM compatible and will let you do almost as much as you could with a desktop computer.

But there is another type of lap computer, the inexpensive kind (if you can call $1,000 and under inexpensive), and these are represented by the Tandy 200, Radio Shack 100, Epson Geneva, and NEC Starlet. These machines are not MS-DOS compatible, but are great for doing light word processing and other computing on the road.

Considering these two types of lap-tops, Tandy`s newest lap portable, the 600, is an enigma. The 600 doesn`t fit into either of these categories. At $1,599 (with one disk drive and the entire line of questionable Microsoft software on ROM chips), it costs almost as much as the MS-DOS-compatible machines, while at the same time providing almost none of the compatibility.

(You can use data files from the Microsoft line of WORD, FILE, PLAN, but none of the regular MS-DOS programs of which there are thousands and thousands.)

The only software you can use is built-in, contained in ROM chips. The only other programs you can use are a few specially written utilities that come on a disk. That`s it.

So here`s the question. Why this machine? Why now? With the exception of the screen (which has three positions, none of which helps you read it), the hardware is nice enough. Great keyboard, solid feel, convenient disk drive. All well-built, and almost the spitting image of the HP 110, with the addition of a disk drive. The 600 is designed to run the MS-WORKS software exclusively, which, rather than being like an exclusive country club, means you run this stuff to the exclusion of all other programs. You can replace the spreadsheet with BASIC, but right now that`s it.

MS-WORKS, while containing word processor, spreadsheet, filer, communications, calendar and calculator programs, is an anemic and poorly thought-out series of programs.

Here`s an example: Which is more important for simple word processing:

being able to center an entire document, or being able to underline a word?

Pretty obvious, isn`t it? Yet this version of Microsoft Word lets you center an entire document, but not underline a single word.

When I edited this article, my file was only 11K long. Because there wasn`t enough memory, it took me about 15 minutes of finagling to move 2K from one end of the file to another. This is ridiculous. At times, I couldn`t start the communications programs until I had deleted all the other files from memory to the disk drive.

The spreadsheet, a version of Multiplan, requires that you call a cell

''r1c1,'' instead of just ''A1.'' This is a slow and cumbersome way to work with a spreadsheet. The telecommunications mode is adequate and does use the XMODEM protocol, which makes it easy to transfer your files to another machine. The calendar program is similar to the one found in the program Sidekick--most helpful.

Everything in the Tandy 600 is done at a snail`s pace. Sometimes, when you load a file from the disk, you can watch the number of lines load, line by painful line.

I applaud the Tandy 1000 and 1200, and look forward to reviewing the AT-compatible Tandy 3000. The 600 just does not rate as well in comparision.