3-31
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.
Figure 3-26. Returning to HALT After a HOLD/HLDA Bus Exchange
HOLD
A19:16
HLDA
CONTROL
AD15:0
AD7:0
A15:8
CLKOUT
Valid
Valid
Previous Value
A1053-0A
Содержание 80C186EA
Страница 1: ...80C186EA 80C188EA Microprocessor User s Manual...
Страница 2: ...80C186EA 80C188EA Microprocessor User s Manual 1995...
Страница 19: ......
Страница 20: ...1 Introduction...
Страница 21: ......
Страница 28: ...2 Overview of the 80C186 Family Architecture...
Страница 29: ......
Страница 79: ......
Страница 80: ...3 Bus Interface Unit...
Страница 81: ......
Страница 129: ......
Страница 130: ...4 Peripheral Control Block...
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Страница 139: ......
Страница 140: ...5 ClockGenerationand Power Management...
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Страница 165: ......
Страница 166: ...6 Chip Select Unit...
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Страница 190: ...7 Refresh Control Unit...
Страница 191: ......
Страница 205: ......
Страница 206: ...8 Interrupt Control Unit...
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Страница 239: ...INTERRUPT CONTROL UNIT 8 32...
Страница 240: ...9 Timer Counter Unit...
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Страница 265: ......
Страница 266: ...10 Direct Memory Access Unit...
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Страница 295: ...DIRECT MEMORY ACCESS UNIT 10 28...
Страница 296: ...11 Math Coprocessing...
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Страница 314: ...12 ONCE Mode...
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Страница 318: ...A 80C186 Instruction Set Additions and Extensions...
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Страница 330: ...B Input Synchronization...
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Страница 334: ...C Instruction Set Descriptions...
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Страница 383: ...INSTRUCTION SET DESCRIPTIONS C 48...
Страница 384: ...D Instruction Set Opcodes and Clock Cycles...
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Страница 408: ...Index...
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