Resources Contact Us Home
Multi-processor DRAM controller that prioritizes row-miss requests to stale banks

Image Number 6 for United States Patent #5745913.

Memory requests from multiple processors are re-ordered to maximize DRAM row hits and minimize row misses. Requests are loaded into a request queue and simultaneously decoded to determine the DRAM bank of the request. The last row address of the decoded DRAM bank is compared to the row address of the new request and a row-hit bit is set in the request queue if the row addresses match. The bank's state machine is consulted to determine if RAS is low or high, and a RAS-low bit in the request queue is set if RAS is low and the row still open. A row counter is reset for every new access but is incremented with a slow clock while the row is open but not being accessed. After a predetermined count, the row is considered "stale". A stale-row bit in the request queue is set if the decoded bank has a stale row. A request prioritizer reviews requests in the request queue and processes row-hit requests first, then row misses which are to a stale row. Lower in priority are row misses to non-stale rows which have been more recently accessed. Requests loaded into the request queue before the cache has determined if a cache hit has occurred are speculative requests and can open a new row when the old row is stale or closed.

  Recently Added Patents
Method for manufacturing non-volatile memory device, non-volatile memory element, and non-volatile memory device
Maintenance guidance display device, maintenance guidance display method, and maintenance guidance display program
Authenticating and off-loading IPTV operations from mobile devices to fixed rendering viewing devices
Method and apparatus for transmitting and receiving a signal in a communication system
Tire tread
Pyridylphenyl compounds for inflammation and immune-related uses
Inhibitor of casein kinase 1delta and casein kinase 1E
  Randomly Featured Patents
Packaging for food and method of producing same
Equalized earphones
Method for evaluating a local flare, correction method for a mask pattern, manufacturing method for a semiconductor device and a computer program product
Method of moving a through-the-flowline installed safety valve through a curved flow line
Dimmer switch
Selective suppression of dry-etch rate of materials containing both silicon and oxygen
Boat with canted wing fins
Self-propelled colonoscope
Apparatus and method for digital up converting in a mobile communication system
Microbial esterase for the enantioselective cleavage of 1-phenylethyl acetate