(19)

(11)

EP 0 148 204 A1

(12)

(43) Date of publication: 17.07.1985 Bulletin 1985/29 (21) Application number: 84902210.0 (22) Date of filing: 25.05.1984

(51) International Patent Classification (IPC):  G11B 23/ 07( . ) (86) International application number: PCT/GB1984/000183 (87) International publication number: WO 1984/004846 (06.12.1984 Gazette 1984/28)

(84) Designated Contracting States: AT BE CH DE FR GB LI LU NL SE (30) Priority: 26.05.1983 GB 19830014559 (71) Applicant: SINCLAIR RESEARCH LIMITED Cambridge CB1 2AQ (GB)	(72) Inventors: WILLIAMS, John, Vaughan Cambridge CB4 4TB (GB) SOUTHWARD, David, Connor Cambridge CB4 4QTB (GB)