Abstract: A method and apparatus for addressing a peripheral interface by mapping into the memory address space of a processor contained in a peripheral controller. The processor in the peripheral controller initializes interface logic within the peripheral controller and in the host system peripheral interface logic to which the peripheral controller is attached to either transmit or receive a block of data. Once initialized, units of data are transmitted across the interface between the peripheral controller and host system using a strobe and acknowledge signal to indicate when data can be taken or placed on data lines. The processor is placed in a wait state as each unit of data is transferred and a watch dog timer is provided to detect any transfer that is not completed within the normal response time of the interface.

Abstract: A method and apparatus for generating a repetitive serial pattern using a recirculating shift register. Use of a recirculating shift register during a disk formatting operation permits a reduction in the amount of memory contained in a peripheral controller that would otherwise be required to format the disk prior to its being available for normal write and read operations.

Abstract: A method and apparatus for defining magnetic disk track field lengths using a programmable counter. Use of a programmable counter in a disk controller permits a reduction in the amount of combinational logic that would otherwise be required to be able to perform the various formatting, reading and writing operations involved in use of just one type of disk and makes it possible to perform these operations on a wide variety of disks having different track and sector formats.