Abstract: A memory control unit (MCU) 22 includes a first interface for interfacing the memory control unit to one or more memory units; a second interface for interfacing the memory control unit to a system bus, including a system data bus for expressing information units, including memory read and write requests, and a system address bus. The MCU further includes logic, responsive to a write request from the system bus, for storing one or more information units within a memory unit at an address specified by the system address bus. The storing logic includes write request receiving and buffer logic having a plurality of storage locations for storing received write requests and associated write addresses prior to the execution of the write requests. The MCU further includes logic, responsive to a read request from the system bus, for reading one or more information units from a memory unit at a location specified by the system address bus.

Abstract: A system bus 12 for an information processing system 10 includes a first group of signal lines 16 whereon command/ID information is time multiplexed with data, and a second group of signal lines 14 for conveying address information. During a first bus cycle command/ID information is presented on the first group of signal lines while the address is presented on the second group of signal lines. During a subsequent bus cycle, and for a data write or data return operation, the first group of signal lines conveys data. Other bus connections, such as cache memories, are thus apprised of the address a full bus cycle before the data is presented thereby providing the bus connections with sufficient time to decode and otherwise operate on the bus information. Multiple word data returns from a system memory are characterized as having the address associated with a particular word of data presented in the immediately prior bus cycle, facilitating the pipelining of data and address information through the system bus.

Abstract: A system console 30 is enabled to read registers from memory boards 12 and 14 and to set registers within the memory boards which control the disabling of one or more memory arrays 16-22. The information read from the memory boards is indicative at least of which of the memory arrays has malfunctioned. The registers are within a memory logic array 40, one of which is disposed upon each of the memory boards 12 and 14 and also upon a memory controlling unit 26, the memory logic arrays being coupled together by a bit serial scan bus 42. In a preferred embodiment of the invention the memory logic arrays 40 are comprised of a highly integrated gate array semiconductor device, each of which is identical. Each memory logic array is provided with a base address input from a preceding memory logic array and computes a base address for a subsequent memory logic array.