The US computer industry has clearly come ravenous back to work from Labor Day and predators are prowling everywhere, red in tooth and claw. Scarcely giving itself time to burp, Santa Monica-based Quarterdeck Corp is swallowing two companies, paying $3m for the intellectual property assets of Prospero Systems Research Inc – and getting a commercial Internet chat server and phone connection software to be incorporated into Quarterdeck’s WebPhone two-way on-line phone system. And it is gobbling down Inset Systems Inc, Brookfield, Connecticut, for 933,000 shares worth $17m. Inset develops a graphics utility HiJaak, and forecasts $6.5m turnover for the year to the month-end.