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80C186EC/80C188EC Microprocessor User's Manual

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BUS INTERFACE UNIT<br />

After several TI bus states, all address/data, address/status and bus control pins drive to a known<br />

state when Powerdown or Idle Mode is enabled. The address/data and address/status bus pins<br />

force a low (0) state. Bus control pins force their inactive state. Figure 3-3 lists the state of each<br />

pin after entering the HALT bus state.<br />

Table 3-6. HALT Bus Cycle Pin States<br />

Pin(s)<br />

No Powerdown<br />

or Idle Mode<br />

Pin State<br />

Powerdown<br />

or Idle Mode<br />

AD15:0 (AD7:0 for 8-bit) Float Drive Zero<br />

A15:8 (8-bit) Drive Address Drive Zero<br />

A19:16 Drive 8H or Zero Drive Zero<br />

BHE (16-bit) Drive Last Value Drive One<br />

RD, WR, DEN, DT/R, RFSH (8-bit), S2:0 Drive One Drive One<br />

3-30

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