Vertical bloch line memory

A method for improving the reliability of readback in VBL memory system of the type having a plurality of stripes, some of such stripes having a VBL pair representing a binary "1" and some of such stripes not having such a VBL pair, the absence of a VBL pair representing a binary "0";

• the method comprising the steps of:
• (a) applying a chopping current to all of said stripes, said chopping current having a sufficient magnitude to chop all of the stripes of said memory system irrespective of whether a VBL pair is contained within each such stripe;
• said chopping current forming chiral bubbles from stripes having a VBL pair and forming unchiral bubbles from stripes not having a VBL pair;
• (b) sorting said chiral bubbles and said unchiral bubbles for collapsing all of said unchiral bubbles;
• and
• (c) detecting said chiral bubbles.

A method of reading data in a VBL memory system, the system of the type having a plurality of stripes in grooves of a magnetic material subjected to a bias magnetic field and further having a stripe expansion conductor adjacent an end of each such stripe and a first chopping conductor connected to a major line for propagating bubbles in said VBL memory system, the first chopping conductor being adjacent the expansion conductor for chopping an expanded stripe head in each said stripe for transferring a bubble onto the major line for determining whether a VBL pair is contained within such bubble, the presence or absence of a VBL pair being determinative of whether the corresponding stripe stored a binary "1" or "0", respectively;

• the method comprising the steps of:
• (a) providing a second chopping conductor not connected to said major line, said second chopping conductor being displaced from said first chopping conductor connected to said major line;
• (b) positioning said chopping conductors so that upon activation of said expansion conductor said stripe head expands into adjacency with either said second chopping conductor or said first chopping conductor connected to said major line depending upon whether said stripe has no VBL pair or has a VBL pair, respectively;
• (c) applying energy to said first chopping conductor connected to said major line for transferring a bubble containing a VBL pair to said major line.