Functions of the control unit
Micro-operation command analysis
Completing an instruction is divided into 4 work cycles
Fetch cycle, address cycle, execute cycle, interrupt cycle
fetch cycle
indirect cycle
execution cycle
interrupt cycle
Functions of the control unit
input signal
output signal:
Example of control signal
Multilevel Sequential System
control method
fixed-length machine cycle
The number of ticks contained in the machine cycle is the same
can be a waste of time
machine cycle of variable length
Another compromise
Using a combination of central and local control
Asynchronous control mode
No reference time scale signal
No fixed cycle beat and strict clock synchronization
Reply
joint control
Combining synchronous and asynchronous
manual control
Reset
Sequential and single instruction execution switch
Meet the shutdown switch (stop if the condition is met)