Selectively controlling the erasure in a magneto-optic recording medium

In a data recorder adapted to record information-bearing signals onto a magnetic record member along record tracks and to sense signals recorded on the magnetic record member along said record tracks;

• the improvement including, in combination:
• magnetic biasing means for supplying a magnetic field to a magnetic record member in the data recorder said magnetic field identifies one of two recording directions, and said magnetic biasing means including means to alternate the recording directions with one of said recording directions being an erasure direction and the second one of said directions being a data-indicating direction;
• indication means operatively coupled to said magnetic biasing means for indicating the recording directions for predetermined portions of said magnetic record member;
• direction means operatively coupled to said indication means for sensing said magnetic field direction for indicating said recording directions at said predetermined portions respectively;
• erasure control means connected to said direction means for indicating a magnetic erasure direction being the same as said indicated recording direction irrespective if one of the recording directions is for erasure or for data-indicating direction and the data-indicating direction being reversed from said indicated recording direction;
• and
• data channel means connected to said erasure means and being operatively coupled to said magnetic record member for recording and reading information-bearing signals on to and from said magnetic record member in accordance with said erasure means indication such that the erasure and recording directions on said magnetic record member alternate on said magnetic record member between said predetermined portions.