Thomas Ledbetter acquired a portable Hyperion personal computer in November. Previously, the president of Pennvest Corp., a 20-person financial planning and real estate investment company in Radnor, Pa., had been lugging an IBM PC from the office to his house night after night, an effort that proved hazardous to his health.

"I literally strained my back the first time I moved the IBM to my home," he remembers.

Ledbetter had acquired two IBMs last September for the Pennvest operation. He and his associates frequently develop real estate plans for investors that analyze cash flow, taxation, and expenses over as much as a 14-year span. Ledbetter had discovered that an 8-bit computer didn't have sufficient memory for his needs. With the PCs, he could do calculations that he says "would take two or three weeks to create" if he did them manually.

Although the IBMs saved him time, Ledbetter found that he rarely had the opportunity to use them during office hours. "I'm on the phone all the time," he says. "I just don't have enough 'alone time' during the day to fiddle."

His only alternative was to do most of his "fiddling" at home, playing what-if games with a VisiCalc spreadsheet program and shuffling numbers to maximize tax breaks for his clients. But getting the PC home was an operation that took an hour of disassembling and reassembling. "The IBM was such a burden," says Ledbetter. "And my wife would object, saying that I was home but I wasn't with her and the kids. They would all be upstairs watching a late movie, and I would be stuck downstairs in the game room with the computer."

When Ledbetter read in a trade magazine that Dynalogic Info-Tech Corp. was introducing the Hyperion, a 16-bit portable the company says is compatible with the IBM PC, he saw the answer to his problems. He immediately obtained one of the new machines. Now he can pack up his portable in just 15 minutes for the trip home and can transfer it easily from room to room once he is there.

"The Hyperion is almost always with me," says Ledbetter. "And, because I can bring it into any room where my family is, I don't feel guilty about bringing work home anymore." He even took it with him on a trip to El Paso, where he chose to "play" with it in his hotel room in the evening rather than go out to a movie.

Ledbetter has been able to use all the software he bought for the IBM on the Hyperion, including VisiCalc and Total Information Management, a database system he uses to maintain a mailing list and organize correspondence. He also can swap files back and forth between the Hyperion and the PCs.

Ledbetter sees portability as the key element in attracting executives to the computer market. "The personal computer has been used mostly for secretarial work," he says. "The executive, by nature, is not going to be tied down to a desk. The portable adapts to your lifestyle, while the personal computer makes you adapt to it."

While the two IBMs remain an integral part of Pennvest's office system, the Hyperion's portability has made it the more popular computer. Both law partner Marc Zaid and Pennvest's CPA, Kathleen Callaghan, compete with Ledbetter for the portable computer for weekend homework or road trips. Ledbetter frequently capitulates -- and gets stuck once again with the IBM. "I wish I had a dozen portables," he says wistfully.