As personal computers go, the TRS 100 isn't the most versatile machine in the world, but it can go wherever you do.

This little lap-sized PC has won a slew of fans for its relative ease of use, its portability and because -- with a modem -- it easily becomes a telecommunications terminal. The machine is a particular favorite with country- and globe-trotting journalists, who can write and file their stories from virtually any phone anywhere. Salesmen, technical service folks and other information-intensive traveling types have made the Model 100 their data-entry device of choice, too.

A price drop to about $299 at Tandy's Radio Shack stores also is nice and helps minimize the 100's limitations: a memory and display screen dimmer than a dying light bulb and only marginally larger than a credit card.

Still, the 100 is wonderfully utilitarian and, because there are Radio Shacks (what a name!) around the country, getting the thing fixed or replaced while you travel shouldn't be all that difficult.

Needless to say, though, there's an awful lot of room for improvement in the 100. While it may have been the first of the lap-sized models, the 100 is a few light years away from being as well designed or as powerful as it could or should be. Clearly, Tandy was more interested in being first to the market than in being best. (By the way, the folks at Tandy don't like criticism of their machines -- they recently canceled all their advertising in CW Communications computer publications after a nasty column appeared in Infoworld.)

Fortunately for Tandy, some third-party suppliers out there have figured out interesting ways to add value to the 100. My current favorite is something called "The Ultimate ROM" from Travelling Software of Seattle (1-800-343-8080)

Ignore the name, but pay attention to the technology. Using a process developed by Polar Engineering of Nikisi, Alaska, Travelling Software has created a custom ROM chip that fits easily into the 100 or 200 Radio Shack PCs. Effectively, the chip is crammed with the software for three programs: a ThinkTank-like outline program, a word processor and a database.

Yes, you can exchange files among the three on a limited basis, so you have the lap-sized counterpart to Lotus 1-2-3 when it comes to integrated software. The software isn't bad and it frees up most of the system's 32K of RAM. That's the beauty of it; you don't need to use the audiocassette programs that eat up valuable RAM.

The chip costs about $230.

I also think that Polar will have a nice growth business in doing semicustom ROMS for companies and government agencies that buy 100s in volume and need to standardize their software. The custom ROM approach is ideal for standardizing communications protocols and sign-ons.

And because the company offers quantity discounts, my guess is that you'll see corporate clients buying the chips in large numbers and giving them out to employes who use the machine. Similarly, if Tandy is smart (not a sure bet), you'll see the company bundling the chip into its lap sales.

Speaking of lap sales, Tandy's strategy is still up in the air. It's not clear how and when the company will drop the price of its Model 200 upgrade from the current $900, or when it will introduce the 102 upgrade to the Model 100. Radio Shack denies there is a 102 upgrade on the way. However, stocks of 100s are low at several of the Radio Shacks I called, and the folks there said they didn't know when the next shipment of 100s was coming.

Clearly, the company needs a good low-priced lap machine; the catch is Tandy's definition of low priced. The 100 shouldn't cost more than $150. If the company were smart, it would trade margin for volume: in other words, keep the price of the 100 low and make up the margins selling the modem and other accessories. I think there's a market out there for low-cost and inexpensive lap machines. For those who have a 100 or are thinking of buying one, the machine's limitations are many. But the software enhancements like Travelling Software's three-in-one ROM can turn the machine into the sort of portable database/outliner/word processor/terminal that information workers on the go can really use.