Range count and main memory address accounting system

摘要

In a peripheral controller of a data processing system having a plurality of system units electrically coupled to a common communication bus for asynchronous intercommunication, an array of counters responsive to both hardware and firmware are connected in a manner to form a serial control data path. Prior to a data transfer, a serial data stream including an offset range count, a range count and a main memory address is shifted through the counters under firmware control. During a data transfer, the firmware enables the hardware control to increment the memory address and decrement the range count to accommodate the higher data transfer rates characteristic of hardware control.