5 temporarily exiting the halt bus state, Figure 326. returning to halt after a hold/hlda b – Intel 80C188XL User Manual

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BUS INTERFACE UNIT

3-30

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.

Figure 3-26. Returning to HALT After a HOLD/HLDA Bus Exchange

HOLD

A19:16

HLDA

CONTROL

AD15:0

AD7:0

A15:8

CLKOUT

A1516-0A

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