Processor system having address allocation and address lock capability

Abstract

In order to make use of row address lock mode of operation of a plurality of memory banks comprising synchronous DRAMs or the like and divided into a plurality of real bank groups, for example, for example, more than the memory banks are grouped into a plurality of logical groups each spanning the real bank groups. Addresses are allocated in unit of each logical group in a block-interleaving manner. When a series of requests issued by a given requester include a plurality of requests for accessing the same row address in the same memory bank, that requester requests that the row address be locked for access by the plurality of requests. The lock request is retained by a row address management unit. When a succeeding request from another requester requests access to a row address other than the locked address in the same memory bank, a priority circuit selects a predetermined number of requests from the initial requester having locked the memory in preference to a request made by the other requester.