3-23
BUS INTERFACE UNIT
Figure 3-21. Typical Write Bus Cycle
Figure 3-22 illustrates a typical 16-bit interface connection to a read/write device. Write bus cy-
cles have many parameters that must be evaluated in determining the compatibility of a memory
(or I/O) device. Table 3-5 lists some critical write bus cycle parameters.
Table 3-4. Write Bus Cycle Types
Status Bits
Bus Cycle Type
S2
S1
S0
0
1
0
Write I/O — Initiated by executing IN, OUT, INS, OUTS instructions or by the
DMA Unit. A15:0 select the desired I/O port. A19:16 are driven to zero (see
Chapter 10, “Direct Memory Access Unit”).
1
1
0
Write Memory —Initiated by any of the Byte/ Word memory instructions or the
DMA Unit. A19:0 selects the desired byte or word memory location.
ALE
S2:0
A19:16
CLKOUT
T1
T2
T3
T4
A18:16 = 0, A19=Valid Status
Valid
A15:0
[AD7:0]
WR
DT/R
DEN
BHE
[A15:8]
Status Valid
Address Valid
Address
Valid
Data Valid
A1047-0A
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...
Страница 81: ......
Страница 127: ......
Страница 128: ...4 Peripheral Control Block...
Страница 129: ......
Страница 137: ......
Страница 138: ...5 ClockGenerationand Power Management...
Страница 139: ......
Страница 154: ...6 Chip Select Unit...
Страница 155: ......
Страница 178: ...7 Refresh Control Unit...
Страница 179: ......
Страница 193: ......
Страница 194: ...8 Interrupt Control Unit...
Страница 195: ......
Страница 227: ......
Страница 228: ...9 Timer Counter Unit...
Страница 229: ......
Страница 253: ......
Страница 254: ...10 Direct Memory Access Unit...
Страница 255: ......
Страница 283: ......
Страница 284: ...11 Math Coprocessing...
Страница 285: ......
Страница 302: ...12 ONCE Mode...
Страница 303: ......
Страница 306: ...A 80C186 Instruction Set Additions and Extensions...
Страница 307: ......
Страница 318: ...B Input Synchronization...
Страница 319: ......
Страница 322: ...C Instruction Set Descriptions...
Страница 323: ......
Страница 371: ......
Страница 372: ...D Instruction Set Opcodes and Clock Cycles...
Страница 373: ......
Страница 396: ...Index...
Страница 397: ......