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80C186EB/80C188EB Microprocessor User's Manual - CEUNES

80C186EB/80C188EB Microprocessor User's Manual - CEUNES

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BUS INTERFACE UNITAfter several TI bus states, all address/data, address/status and bus control pins drive to a knownstate when Powerdown or Idle Mode is enabled. The address/data and address/status bus pinsforce a low (0) state. Bus control pins force their inactive state. Figure 3-3 lists the state of eachpin after entering the HALT bus state.Table 3-6. HALT Bus Cycle Pin StatesPin(s)No Powerdownor Idle ModePin StatePowerdownor Idle ModeAD15:0 (AD7:0 for 8-bit) Float Drive ZeroA15:8 (8-bit) Drive Address Drive ZeroA19:16 Drive 8H or Zero Drive ZeroBHE (16-bit) Drive Last Value Drive OneRD, WR, DEN, DT/R, RFSH (8-bit), S2:0 Drive One Drive One3-29

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