Holographic Memory Storage is a relatively simple concept. Data, rather then being stored in two dimensions, is instead stored three dimensionally. This allows for tighter data compression, as well as massively increased storage space for the same amount of volume. For example, a one-inch cube can now hold as much as 150 gigabytes or more.
Data is stored holographically by being 'burned' into the memory plastic cube by a low-powered laser. This is done layer by layer, until the entire cube is full. Of course, as with any other storage medium, the data-cubes used in this process do not have to be filled to capacity.
Data is retrieved by the simple expedient of shining a low-powered laser through the particular bit of information that is needed, and is then converted into electronic form and carried to the display.