Abstract: A method and apparatus for performing efficient reseeks in an optical storage device. As data sectors are read by the optical storage device, address information corresponding to sectors being processed by the optical storage device is stored in a stack. The stack may be composed of shift registers that shift the address information of new sectors down the stack as they are read. When an interrupt occurs, a selector determines which stack location contains address information for the sector being processed, and transfers the address information to a register. The address information is held in the register until it is accessed by a microprocessor. The microprocessor uses the address information to determine a reseek location, and causes the sector being processed to be read again.

Abstract: A method and apparatus for performing efficient reseeks in an optical storage device. As data sectors are read by the optical storage device, address information corresponding to sectors being processed by the optical storage device is stored in a stack. The stack may be composed of shift registers that shift the address information of new sectors down the stack as they are read. When an interrupt occurs, a selector determines which stack location contains address information for the sector being processed, and transfers the address information to a register. The address information is held in the register until it is accessed by a microprocessor. The microprocessor uses the address information to determine a reseek location, and causes the sector being processed to be read again.

Abstract: A virtual monitor controller includes a data storage device coupled to receive and output data; an instruction storage device coupled to receive and output instructions; a status storage device coupled to receive and output status data; and a mode storage device coupled to receive and output mode data. The virtual monitor controller is included in a debugger/monitor controller. A debugger/monitor system comprises a host system; the debugger/monitor controller; and a digital processor. Preferably, the controller is coupled between the processor and IC logic. A method of operating a virtual monitor comprises the steps of intercepting an instruction fetch from a microprocessor; downloading instructions from a host computer; and operating the microprocessor with the instructions. Preferably, the instructions are sequentially downloaded.

Abstract: The dual port disk drive interface circuit enables a plurality of dual port disk drives to be interconnected with a plurality of control units in a manner that is transparent to both the dual port disk drives and the control unit. The dual port disk drive interface circuit is interposed between the two channels from n control units and the dual ports of m dual port disk drives to switchably interconnect each control unit with an available dual port disk drive. The interface circuit intercepts the control signals that are generated by both the control units and the dual port disk drives and modifies these control signals to emulate the interconnection of each control unit with a dedicated dual port disk drive. The interface circuit controls the routing of data between the control unit and the available ports on the plurality of dual port disk drives to multiply the number of ports available on the dual port disk drive without modification of the control unit or the dual port disk drive.