(19)

(11)

EP 0 290 465 A1

(12)

(43) Date of publication: 17.11.1988 Bulletin 1988/46 (21) Application number: 87901236.0 (22) Date of filing: 29.01.1987

(51) International Patent Classification (IPC):  G06F 9/ 28( . ) G06F 9/ 38( . ) G06F 9/ 22( . ) (86) International application number: PCT/US1987/000178 (87) International publication number: WO 1987/004821 (13.08.1987 Gazette 1987/18)

(84) Designated Contracting States: CH DE FR GB IT LI NL (30) Priority: 29.01.1986 US 19860823776 (60) Divisional application: 92201162.2 / 0500193 (71) Applicant: DIGITAL EQUIPMENT CORPORATION Maynard Massachusetts 01754-1418 (US)	(72) Inventors: CLARK, Douglas, W. Medford, MA 02155 (US) BERNSTEIN, Debra Sudury, MA 01776 (US) (74) Representative: Goodman, Christopher, et al  Eric Potter & Clarkson St. Mary's Court St. Mary's Gate Nottingham NG1 1LE Nottingham NG1 1LE (GB)