copy a matrix into another one, with offset

    Jan 11 2013 | 2:53 am
    hi there, a final output matrix, displaying blank screen at the beginning another matrix with content changing each x seconds. both same width, but the second one is 1/8 height of the first one.
    The big one has to be filled progressively, each x seconds, by the content of the small one, using offset in a cycle, after x second, the first 1/8 is filled. then after x, the second 1/8 (the first 1/8 still contains the previous stuff)
    etc till the end where all become blank again
    struggling with @usedstdim and the other companions in tutorial 16 and the content of the smallest is always copied at the bottom strangely.
    Here is the machine:
    any leads would totally unstick me :)