Video display system using memory with parallel and serial access employing selectable cascaded serial shift registers
First Claim
1. In a memory device having an array of memory cells, address terminals, a data input terminal, a data output terminal, means responsive to address signals received by said address terminals for addressing a memory cell in said array, means for writing data presented at said data input terminal to an addressed memory cell, and means for reading data contained in an addressed memory cell so that said data is presented at said data output terminal, the improvement comprising:
- a register comprised of a plurality of memory cells;
means, coupled to said array and to said register, for transferring the contents of a predetermined number of memory cells in said array to memory cells in said register;
a serial output terminal;
serial output means, connected to said serial output terminal and connectable to a memory cell in said register, for communicating the contents of said selected memory cell to said serial output terminal;
means for selecting a memory cell in said register to be connected to said serial output means, responsive to an address signal received by said address terminals;
a serial clock terminal for receiving a clock signal;
shifting means, connected to said serial clock terminal, for shifting the contents of another memory cell in said register to said serial output means so that, responsive to a series of said clock signals received by said serial clock terminal, the contents of a series of memory cells in said register are presented at said serial output terminal, beginning with the contents of the memory cell in said register selected by said selecting means;
a transfer control terminal for receiving a transfer control signal; and
transfer control means, connected to said transfer control terminal and to said transferring means, for enabling and disabling said transferring means responsive to said transfer control signal, so that during such time as said transferring means is disabled, data may be written to and read from any of said memory cells in said array independently from the presentation of data at said serial output terminal.
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Accused Products
Abstract
In a computer system, an improved memory circuit is provided for accomodating video display circuits with CRT screens having different resolutions. The memory circuit includes a bit-mapped RAM unit or chip having sufficient cells to accomodate any CRT screen intended to be used, and it further includes a serial shift register having a plurality of taps at locations corresponding to different preselected columns of cells in the chip. In the system, provision is included for selecting taps to unload only the portion of the shift register containing the bits of interest, whereby unused portions of the chip may be effectively excluded and the time for transferring data of interest to the CRT screen is reduced.
169 Citations
26 Claims
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1. In a memory device having an array of memory cells, address terminals, a data input terminal, a data output terminal, means responsive to address signals received by said address terminals for addressing a memory cell in said array, means for writing data presented at said data input terminal to an addressed memory cell, and means for reading data contained in an addressed memory cell so that said data is presented at said data output terminal, the improvement comprising:
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a register comprised of a plurality of memory cells; means, coupled to said array and to said register, for transferring the contents of a predetermined number of memory cells in said array to memory cells in said register; a serial output terminal; serial output means, connected to said serial output terminal and connectable to a memory cell in said register, for communicating the contents of said selected memory cell to said serial output terminal; means for selecting a memory cell in said register to be connected to said serial output means, responsive to an address signal received by said address terminals; a serial clock terminal for receiving a clock signal; shifting means, connected to said serial clock terminal, for shifting the contents of another memory cell in said register to said serial output means so that, responsive to a series of said clock signals received by said serial clock terminal, the contents of a series of memory cells in said register are presented at said serial output terminal, beginning with the contents of the memory cell in said register selected by said selecting means; a transfer control terminal for receiving a transfer control signal; and transfer control means, connected to said transfer control terminal and to said transferring means, for enabling and disabling said transferring means responsive to said transfer control signal, so that during such time as said transferring means is disabled, data may be written to and read from any of said memory cells in said array independently from the presentation of data at said serial output terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A memory device comprising:
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an array of memory cells, said memory cells arranged in rows and columns; address input means, for receiving row address, column address, and serial address signals; row address means, for selecting a row in said array responsive to said address input means receiving a row address signal; column address means, for selecting a column in said selected row responsive to said address input means receiving a column address signal; random input means, for writing data to said memory cell selected by said column address means; random output means, for presenting the contents of said memory cell selected by said column address means; a register comprises of a plurality of memory cells; means for transferring the contents of the memory cells in said selected row of said array into the memory cells of said register; serial output means, connected to a selected memory cell in said register, for presenting the contents of said selected memory cell in said register; serial selecting means for selecting, responsive to said address input means receiving a serial address signal, a memory cell in said register to be connected to said serial output means; means, responsive to a serial clock signal, for shifting to the serial output means the contents of another memory cell in said register so that, upon a series of said serial clock signals, the contents of a series of memory cells in said register will be presented by said serial output means; and transfer control means, responsive to a transfer control signal, for selectively enabling and disabling said transferring means so that, when said transferring means is disabled, data may be written to and read from any of said memory cells in said array independently from the presentation of data by said serial output means. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A data processing system comprising:
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a data processing unit; utilization means for utilizing data processed by said data processing unit; and memory means for storing data, comprising; an array of memory cells, said memory cells arranged in rows and columns; address input means, for receiving row address, column address, and serial address signals; row address means, for selecting a row in said array responsive to said address input means receiving a row address signal; column address means, for selecting a column in said selected row responsive to said address input means receiving a column address signal; random input means, for writing data to said memory cell selected by said column address means; random output means, for presenting the contents of said memory cell selected by said column address means; a register comprised of a plurality of memory cells; means for transferring the contents of the memory cells in said selected row of said array into the memory cells of said register; serial output means, connected to a selected memory cell in said register, for presenting the contents of said selected memory cell in said register; serial selecting means for selecting, responsive to said address input means receiving a serial address signal, a memory cell in said register to be connected to said serial output means; means, responsive to a serial clock signal, for shifting to the serial output means the contents of another memory cell in said register so that, upon a series of said serial clock signals, the contents of a series of memory cells in said register will be presented by said serial output means; and transfer control means, responsive to a transfer control signal, for selectively enabling and disabling said transferring means so that, when said transferring means is disabled, data may be written to and read from any of said memory cells in said array independently from the presentation of data by said serial output means. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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Specification