Physical cache unit for computer

Abstract

A physical cache unit (100) is used within a computer (20). The computer (20) further includes a main memory (99) a memory control unit (22), inputs/output processors (54, 68) and a central processor (156). The central processor includes an address translation unit (118), an instruction processing unit (126), an address scalar unit (142), a vector control unit (144) and vector processing units (148, 150). The physical cache unit (100) stores operands in a data cache (180), the operands for delivery to and receipt from the control processor (156). Addresses for requested operands are received from the central processor (156) and are examined concurrently during one clock cycle in tag stores (190 and 192). The tag stores (190 and 192) produce tags which are compared in comparators (198 and 200) to the tag of physical addresses received from the central processor (156). If a comparison is made, a hit, both of the requested operands are read, during one clock period, from the data cache (180) and transmitted to the central processor (156). If the requested operands are not in the data cache (180) they are fetched from the main memory (99). The operands requested from the main memory (99) within a block are placed in a buffer (188) and/or transmitted directly through a bypass bus (179) to the central processor (156). Concurrently, the block of operands fetched from main memory (99) may be stored in the data cache (180) for subsequent delivery to the central processor (156) upon request. Further, a block of operands from the central processor (156) can be transmitted directly to the memory control unit 22 and bypass the data cache (180).