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Apparatus for selectively loading data blocks from CD-ROM disks to buffer segments using DMA operations

  • US 5,664,224 A
  • Filed: 12/18/1995
  • Issued: 09/02/1997
  • Est. Priority Date: 07/23/1993
  • Status: Expired due to Term
First Claim
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1. A data processing system comprising:

  • (a) means for receiving requests for data from a storage device,(b) a buffer memory having a plurality of segments for storing data in a main memory,(c) a memory location pointer having a plurality of bits, wherein each of the plurality of bits corresponds to a respectively different one of said plurality of segments,(d) a central processing unit including means for writing binary data values into said memory location pointer, wherein said binary data values indicate availability of each of said plurality of segments for data transfer, and(e) a DMA controller unit which includes;

    means for managing a direct memory access by directly reading blocks of data from the storage device and for transferring the blocks of data into selected ones of said plurality of segments responsive to the corresponding bits of the memory location pointer, andmeans for changing the binary values corresponding to the segments into which the blocks of data were stored to indicate that the segments are currently not available for data transfer.

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