ALTERNATE MASTER BURSTING DATA RATE MANAGEMENT TECHNIQUES FOR USE IN COMPUTER SYSTEMS HAVING DUAL BUS ARCHITECTURE

摘要

Methods and apparatus are set forth which optimize andbalance the use of processor card (or complex) resources(e. g., memory, the local bus, etc .), with the use of othersystem resources, such as the card to card communicationsbus and devices attached thereto, in dual bus computingsystems. A new data rate management technique reduces datatransfer overhead particularly for burst mode transfers.The invention promptly services pending memory refreshrequests; limits multiple accesses to on card (or processorcomplex) memory by an Alternate Bus Master to apredetermined number of cycles where the processor requeststhe use of its local bus; and allows an Alternate Bus Masterunlimited accesses to the processor local bus when theAlternate Bus Master owns the card to card communicationsbus and the processor subsequently requests that bus. Theaforementioned balance of resources is achieved using a BusHold On Grant ("BSHOG") scheduling procedure which, assuminga bursting Alternate Bus Master has gained control of thelocal processor bus and is conducting data transfer cycleswhen the processor requests the local bus, allows theAlternate Bus Master to conditionally retain local busownership over a plurality of Alternate Bus Master datatransfer cycles.