Intel 80C186XL User Manual
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.
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.
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