Abstract: The present invention is useful in a data processing system having a data processor coupled to a SCSI channel disposed for transmitting and receiving data between the data processor and a peripheral storage subsystem. The present invention is a method for controlling a bridge controller that permits expanding the maximum allowable number of disk drives connectable to the SCSI channel. In particular the method comprises the steps of receiving a command from the SCSI channel; initializing queue pointers from a memory in response to the command; determining the command type and setting flags and pointers in response thereto; when the command is a write operation, transferring data from the SCSI channel and storing the data in the memory; selecting a disk drive to receive the data by sending message and command bytes to the disk drive; and, transferring the data from the memory to the selected disk drive.

Abstract: A peripheral-controller (called a Data Link Processor) optimizes the rate of data transfers between a host computer and magnetic tape peripherals by use of a block counter sensing system for monitoring the occupation-status of word-blocks in a buffer memory. The peripheral-controller provides Automatic Read/Write Logic for buffer-peripheral tape transfers and a burst mode routine for rapid host-buffer transfers of data words. The sensing system provides means to inform a microcode sequencer when certain action routines should be executed in order to maintain steady error-free data transfer operations which minimize the need for retries of data transfer cycles previously initiated.