US sales of personal computer software rose 40% last year to total $2,870m, but there was a tailing off in the fourth quarter, reports the US Software Publishers Association, which says that US firms also sold $815m of software abroad: the fourth quarter slowing, to 32%, may have had more to do with a very storng fourth quarter 1987 and a lack of hot new products than on any underlying weakness in the computer end of the economy, and lack of a hot new property hit the biggest sector of the market, MS DOS spreadsheets, which fell by 5% in the fourth quarter to hit $101.7m; for the full year, sales of spreadsheets also lagged, at $473m up 28%, trailing word processing software, which soared 47% to $494.5m.