International Data Corp has now done its own sums on the personal computer market in 1996 and reckons that worldwide unit shipments rose 16% last year, marking the first year since 1991 in which sales did not increase by at least 20%. US shipments rose 15% following a very strong 1995, it says, adding that the fourth quarter was weak worldwide, growing only 11%, mainly because of depressed sales in Europe. Compaq Computer Corp was number one in both the US and the global markets for the third straight year, but IBM Corp gained market share for the first time since 1993 at the expense of Apple Computer Inc, and Hewlett-Packard Co made the top five worldwide for the first time.