BUS INTERFACE UNIT
3-10
Figure 3-9. T-State and Bus Phases
3.4.1
Address/Status Phase
Figure 3-10 shows signal timing relationships for the address/status phase of a bus cycle. A bus
cycle begins with the transition of ALE and S2:0. These signals transition during phase 2 of the
T-state just prior to T1. Either T4 or TI precedes T1, depending on the operation of the previous
bus cycle (see Figure 3-8 on page 3-9).
ALE provides a strobe to latch physical address information. Address is presented on the multi-
plexed address/data bus during T1 (see Figure 3-10). The falling edge of ALE occurs during the
middle of T1 and provides a strobe to latch the address. Figure 3-11 presents a typical circuit for
latching addresses.
The status signals (S2:0) define the type of bus cycle (Table 3-1). S2:0 remain valid until phase
1 of T3 (or the last TW, when wait states occur). The circuit shown in Figure 3-11 can also be
used to extend S2:0 beyond the T3 (or TW) state.
T4
or TI
T1
T2
T3
or TW
CLKOUT
Address/
Status Phase
Data Phase
T4
or TI
A1113-0A
Содержание 80C186XL
Страница 1: ...80C186XL 80C188XL Microprocessor User s Manual...
Страница 2: ...80C186XL 80C188XL Microprocessor User s Manual 1995...
Страница 18: ...1 Introduction...
Страница 19: ......
Страница 27: ......
Страница 28: ...2 Overview of the 80C186 Family Architecture...
Страница 29: ......
Страница 79: ......
Страница 80: ...3 Bus Interface Unit...
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Страница 127: ......
Страница 128: ...4 Peripheral Control Block...
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Страница 137: ......
Страница 138: ...5 ClockGenerationand Power Management...
Страница 139: ......
Страница 154: ...6 Chip Select Unit...
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Страница 178: ...7 Refresh Control Unit...
Страница 179: ......
Страница 193: ......
Страница 194: ...8 Interrupt Control Unit...
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Страница 227: ......
Страница 228: ...9 Timer Counter Unit...
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Страница 254: ...10 Direct Memory Access Unit...
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Страница 284: ...11 Math Coprocessing...
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Страница 302: ...12 ONCE Mode...
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Страница 306: ...A 80C186 Instruction Set Additions and Extensions...
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Страница 318: ...B Input Synchronization...
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Страница 322: ...C Instruction Set Descriptions...
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Страница 372: ...D Instruction Set Opcodes and Clock Cycles...
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Страница 396: ...Index...
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