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Video memory with flash fill

  • US 5,422,998 A
  • Filed: 11/15/1993
  • Issued: 06/06/1995
  • Est. Priority Date: 11/15/1993
  • Status: Expired due to Term
First Claim
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1. An apparatus for addressing and modifying data in a row addressable memory which stores a plurality of lines of information and is placed on an integrated circuit, said row addressable memory receiving row address, color data, start address, end address, and logic function data, said start address and said end address defining a portion of data at said row address to be modified according to said color data and said logic function data, wherein modification of said portion of data is to be performed simultaneously, and said start address and said end address to permit as a maximum size an entire row of said row addressable memory corresponding to an entire line of displayed video, said apparatus on said integrated circuit comprising:

  • a memory array with row address circuitry for selecting a row in said memory array, wherein an entire row of memory cell data, of said row, being simultaneously available during read operations, and said entire row of memory cells being simultaneously available during write operations;

    a data latch means for storing said entire row of memory cell data of said row of said memory array;

    a fill unit with a plurality of stages corresponding to all memory cell addresses in said row of said memory array, each fill unit stage employing one address compare unit and an individual bit processing unit for each bit plane of said memory array, said address compare unit employing a first address comparator to compare said start address with a fixed address corresponding to said fill unit stage, a second address comparator to compare said end address with said fixed address of said fill unit stage, and a combinatorial logic circuit to combine outputs of said first address comparator and said second address comparator, each said bit processing unit employing logic gates which modify data from said data latch means according to said logic function data, said color data, and the combinatorial logic circuit, wherein when said fixed address of said stage is greater than or equal to said start address and less than or equal to said end address, said data from said data latch means is modified according to said color data and said logic function data, otherwise said data from said data latch means is not modified.

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