Storage controller for a personal computer

This invention relates to personal computers, and more particularly to a storage controller for a personal computer. The small computer systems interface (SCSI) controller is coupled directly to the local processor bus for controlling data transfer with storage memory devices such as fixed or removable media electromagnetic storage devices. The personal computer 10 has a high speed local processor data bus 34 and a storage controller 40 coupled directly to the local processor bus for regulating communications between a processor 32 and storage memory devices 36. The storage controller 40 has at least one counter 60 for tracking at least one of address and count data for blocks of data being transferred and capable of signalling through the local processor bus the state of the counter, and a bi-stable device 61 interposed between the local processor bus of data representing an initial state of the counter at the beginning of a transfer of blocks of data and for continuing delivery of initial state data throughout a transfer of blocks of data. The counter and bi-stable device cooperate for permitting one of incrementing and decrementing of the counter during transfer of blocks of data while avoiding changes in counter state data delivered to the local processor bus during transfer of blocks of data.