In a television viewing system, a VCR adapted for use with a source of cable TV, a remotely controllable cable box and a remotely controllable TV receiver provides means to determine all channels tunable by the various tuners, including pay channels. A memory disposed within the VCR stores operative...http://www.google.com.hk/patents/US5420647?utm_source=gb-gplus-share專利 US5420647 - T.V. viewing and recording system
