Abstract: A disk address controller includes: a random access memory for storing the upper and lower limit addresses of the access area of each of processing units which are allotted to a disk unit, and storing the disk address specified by a disk input/output instruction from the processing unit; a read only memory for storing a microprogram corresponding to the disk input/output instruction; a microprocessor for executing the microprogram; disk channel units provided corresponding to the respective disk units; and a direct memory access control unit for performing data transfer with the disk unit via the disk channel. The disk address controller sets up the upper and lower addresses of the area arbitrarily allotted to the disk unit by the processing unit.

Abstract: A roll-up method for a display unit according to this invention consists of supplying data for designating a roll-up region to a roll-up address counter to designate an address for a refresh memory storing a character display data portion and a control data portion and modifying the contents of said address counter to modify the stored information of said refresh memory in a fly-back time of the display unit by means of a roll-up instruction, thereby rolling up said region.