William M Ledbetter

US Patent:

56665091, Sep 9, 1997

Filed:

Mar 24, 1994

Appl. No.:

8/216998

Inventors:

Daniel M. McCarthy - Phoenix AZ
Joseph C. Circello - Phoenix AZ
Richard Duerden - Scottsdale AZ
Gregory C. Edgington - Scottsdale AZ
Cliff L. Parrott - Austin TX
William B. Ledbetter - Austin TX

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

G06F 1210

US Classification:

711206

Abstract:

A processor (10) has a data cache unit (16) wherein the data cache unit includes a memory management unit (MMU) (32). The MMU contains memory locations within transparent translation registers (TTRs), an address translation cache (40), or a table walk controller (42) which store or generate cache mode (CM) bits which indicate whether a memory access (i. e. , a write operation) is precise or imprecise. Precise operations require that a first write operation or bus write instruction be executed with no other operationsnstructions executing until the first operation/instruction completes with or without a fault. Imprecise operations are operations/instruction which may be queued, partially performed, or execution simultaneously with other instructions regardless of faults or bus write operations. By allowing the logical address to determine whether the bus write operation is precise or imprecise, a large amount of system flexibility is achieved.