Unisys Corporation

Sperry Corporation

William L Borgerding

Mitchell A Bauman

Kelvin S Vartti

Conrad S Shimada

Vithal R Patel

An apparatus for and method of improving the efficiency of a level two cache memory. In response to a level one cache miss, a request is made to the level two cache. A signal sent with the request identifies when the requester does not anticipate a near term subsequent use for the requested data element. If a level two cache hit occurs, the requested data element is marked as least recently used in response to the signal. If a level two cache miss occurs, a request is made to level three storage. When the level three storage request is honored, the requested data element is immediately flushed from the level two cache memory in response to the signal.

Leaky cache mechanism

A method and apparatus for performing a two's complement, single or double precision digital multiply, whereby the multiplication is performed in a one's complement format in a gate array assembly and then converted to a two's complement format. The gate array assembly generally multiplying successive eight bit bytes of the multiplier two bits at a time in each of four ranks to the full width multiplicand and producing a partial sum and carry at the end of each cycle. Each partial sum and carry then being fedback, aligned and added into the partial sum and carry produced during the multiplication of the next successive multiplier byte, until the multiplication is complete and at which time the final partial carry is converted and added to the final partial product to produce the final product.

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Minneapolis, MN, United States of America

William L Borgerding