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BUS INTERFACE UNIT
3.5.5
Temporarily Exiting the HALT Bus State
A DMA request, refresh request or bus hold request causes the BIU to exit the HALT bus state
temporarily. This can occur only when in the Active or Idle power management mode. The BIU
returns to the HALT bus state after it completes the desired bus operation. However, the BIU
does not execute another bus HALT cycle (i.e., ALE and bus cycle status are not regenerated).
Figures 3-26, 3-27 and 3-28 illustrate how the BIU temporarily exits and then returns to the
HALT bus state.
CLKOUT
HOLD
HLDA
AD15:0
AD7:0
A15:8
A19:16
CONTROL
Figure 3-26. Returning to HALT After a HOLD/HLDA Bus Exchange
3-30
A1516-0A
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