(19)

(11)

EP 0 490 969 A1

(12)

(43) Date of publication: 24.06.1992 Bulletin 1992/26 (21) Application number: 90913848.0 (22) Date of filing: 05.09.1990

(51) International Patent Classification (IPC):  G06F 15/ 02( . ) (86) International application number: PCT/GB1990/001372 (87) International publication number: WO 1991/003787 (21.03.1991 Gazette 1991/07)

(84) Designated Contracting States: CH DE FR GB LI NL SE (30) Priority: 06.09.1989 GB 19890019680 (71) Applicant: ST ANDREWS ELECTRONICS LIMITED St. Andrews, Fife KY16 9SR (GB)	(72) Inventor: BRADBURY, Charles, Kinder Fife KY6 3PB (GB) (74) Representative: Pattullo, Norman  Murgitroyd and Company 373 Scotland Street Glasgow G5 8QA Glasgow G5 8QA (GB)