Storage of digitized video images on disk

A multiple channel parallel transfer digital disk recorder is used to record digitized circular video images at the video frame rate. The digital pixel values for each image frame are written onto successive pages of a disk buffer memory (DBM) under video frame timing and are read from memory and written on disk under disk timing. When the last page image of the DBM is reached readout is switched back to the first page which is now filled with a frame of image data. Reading image data from disk and writing into successive pages of the DBM is done similarly. Only DBM locations containing pixels representative of actual image data within the circular boundaries of the image are addressed when reading from DBM and writing on disk and when reading from disk and writing onto DBM. Adjacent pixels in the image having predetermined bit lengths are written on disk with their bits in series. A group of adjacent pixels are written simultaneously and in coincident locations on the several disks under clocks that are derived from disk. A circuit is provided for correcting for the skew that can exist as a result of asynchronism between the timing of the disk. A programmable serial-to-parallel converter is provided for converting the serially recorded pixel of any bit length back to parallel bits of the same number as before they were serialized. The commands for the disk drive such as read, write, step and select cylinder are put in registers in response to occurrence of a disk index pulse for one multiple disk rotation and they are shifted to corresponding registers and are ready for execution when the next index pulse occurs so what is to be done by the disk drive during the next disk rotation is anticipated.