BUS INTERFACE UNIT
3-36
Figure 3-32. Qualifying DEN with Chip-Selects
3.6.2
Synchronizing Software and Hardware Events
The execution sequence of a program and hardware events occurring within a system are often
asynchronous to each other. In some systems there may be a requirement to suspend program ex-
ecution until an event (or events) occurs, then continue program execution.
One way to synchronize software execution with hardware events requires the use of interrupts.
Executing a HALT instruction suspends program execution until an unmasked interrupt occurs.
However, there is a delay associated with servicing the interrupt before program execution can
proceed. Using the WAIT instruction removes the delay associated with servicing interrupts.
A
B
D15:8
OE
T
DEN
MCS0
Buffer
8
AD15:8
8
A
B
D7:0
OE
T
Buffer
8
AD7:0
8
DT/R
8
Buffered
Data
Bus
Local
Data
Bus
8
A1058-0B
Summary of Contents for 80C186XL
Page 1: ...80C186XL 80C188XL Microprocessor User s Manual...
Page 2: ...80C186XL 80C188XL Microprocessor User s Manual 1995...
Page 18: ...1 Introduction...
Page 19: ......
Page 27: ......
Page 28: ...2 Overview of the 80C186 Family Architecture...
Page 29: ......
Page 79: ......
Page 80: ...3 Bus Interface Unit...
Page 81: ......
Page 127: ......
Page 128: ...4 Peripheral Control Block...
Page 129: ......
Page 137: ......
Page 138: ...5 ClockGenerationand Power Management...
Page 139: ......
Page 154: ...6 Chip Select Unit...
Page 155: ......
Page 178: ...7 Refresh Control Unit...
Page 179: ......
Page 193: ......
Page 194: ...8 Interrupt Control Unit...
Page 195: ......
Page 227: ......
Page 228: ...9 Timer Counter Unit...
Page 229: ......
Page 253: ......
Page 254: ...10 Direct Memory Access Unit...
Page 255: ......
Page 283: ......
Page 284: ...11 Math Coprocessing...
Page 285: ......
Page 302: ...12 ONCE Mode...
Page 303: ......
Page 306: ...A 80C186 Instruction Set Additions and Extensions...
Page 307: ......
Page 318: ...B Input Synchronization...
Page 319: ......
Page 322: ...C Instruction Set Descriptions...
Page 323: ......
Page 371: ......
Page 372: ...D Instruction Set Opcodes and Clock Cycles...
Page 373: ......
Page 396: ...Index...
Page 397: ......