Apparatus and method for observing the mode of a memory device
DCFirst Claim
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1. A method for observing a control register in a memory device, the control register defining an operation of the memory device, the control register not observable from the memory device, the method comprising the steps of:
- storing a received value in the control register responsive to a first signal;
outputting the received value responsive to a second control signal when no output is expected from the memory device; and
disabling the operation of the memory device responsive to the second control signal subsequent to the step of outputting.
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Abstract
A method and apparatus observes a mode register (102) in a synchronous memory device. A multiplexer (306) selects the value of the mode register (102) or the conventional data path of the memory array (302) through the output buffer. The invention outputs the stored value of the control register (102) on output pins, such as address pins when no signal is expected. The multiplexer (306) maybe responsive to a variety of control signals.
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15 Claims
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1. A method for observing a control register in a memory device, the control register defining an operation of the memory device, the control register not observable from the memory device, the method comprising the steps of:
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storing a received value in the control register responsive to a first signal; outputting the received value responsive to a second control signal when no output is expected from the memory device; and disabling the operation of the memory device responsive to the second control signal subsequent to the step of outputting. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for observing a mode of a memory device comprising:
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a multiplexer selectively outputting either a first input or a second input responsive to a first control signal; a first register storing a first value defining an operation of the memory device, the first register generating the first input; a memory array storing a plurality of data bits responsive to received addresses, the memory array generating the second input; and control logic generating the first control signal responsive to a received signal indicative of a power down command, the control logic generating the first control signal when no output is expected from the memory device. - View Dependent Claims (7, 8, 9)
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10. An apparatus for observing a mode of a memory device comprising:
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a gating means for selectively outputting either a first input or a second input responsive to a first control signal; a register storing a value defining an operation of the memory device, the register generating the first input; storage means for storing a plurality of data bits responsive to received addresses, the storage means generating the second input; and control logic generating the first control signal responsive to a predetermined value of the register. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification