What do a 27-pound radish and a Ricoh PF-1 have in common? Very little, except that each has been recognized by The Guinness Book of Records. The one that fits handily into a briefcase is cited as the world's smallest facsimile machine, and is thus a strong candidate for inclusion in a record Inc. itself herein attempts to compile: the world's tiniest desktop.

Ricoh's lilliputian fax measures 11 by 7 by 2 inches and weighs 5.5 pounds. It sends and receives conventional letter-size documents at standard rates and resolutions, and serves as a copier as well. When powered by battery and fitted with the appropriate interface, it can be coupled to a cellular phone or even a pay phone. Suggested retail: $1,695; Ricoh Corp., 800-637-4264.

Claim to the tiniest DOS-compatible PC on the market was made this past spring by Hewlett-Packard with the introduction of its 6.25-by-3.5-by-1-inch HP 95LX palmtop. The 11-ounce machine uses an 80C88-type processor and runs Lotus 1-2-3 and other built-in business applications. Suggested retail: $699; Hewlett-Packard, 800-443-1254.

Computers can't get much smaller, since the fingers that type on them aren't likely to shrink. On the other hand -- or head, in this case -- full functionality and minuscule footprint come together in the ComPCap, an 8088-microprocessor computer worn on a hat and activated by voice. By midget mirrors, the computer's "monitor" is seemingly projected a foot or two in front of the user, who views it through a pair of special glasses. Since nothing physically touches a surface (the device is designed for hands-free use in manufacturing, construction, medicine, and the like), the computer takes up no space at all. Suggested retail: $3,995; Park Engineering Asso-ciates, 509-487-6462.

For a high-output, letter-quality printer, we go with the Mannesmann Tally MT735 at 11 by 9 by 2.5 inches -- small enough to snuggle into a briefcase alongside our chosen fax. The 8.3-pound thermal-transfer machine produces six text pages a minute at a respectable 300 dots per inch, and is powered by a rechargeable built-in battery. Suggested retail: $1,295; Mannesmann Tally, 800-843-1347.

The entire workings of our nightstand-size office can be stored on the Disctec RHD 60, a 3.2-by-5-by-.81-inch hard-disk drive that has an ample 60 megabytes of capacity. The IBM-compatible 7-ounce drive is removable; therefore it, too, can be thrown (carefully) into our briefcase. Suggested retail: $895; Disk Technologies, 800-553-0337.

There you have our record-setting basic collection. Granted, serious contenders do exist, but as far as function as a factor of size goes, we'll stand by a computer, a hard disk, a printer, and a fax/copier that occupy a scant one and a half square feet. Plus, of course, a size 7 1/2 cap.

-- Robert A. Mamis