PFCA401SF 3BSE024387R4 Control unit ABB

(1) Instruction register.
The opcode portion of an instruction from an instruction register. The control unit decodes the opcode part. Indicate what this instruction does so that different control signals are given to different instructions during the execution phase of the instruction.

(2) Clock signal.
The control unit works under the control of the clock signal. A variety of microoperation commands are issued at a specified point in time under the control of a clock signal. A clock pulse can issue one or a group of microoperation commands that can be executed in parallel.

(3) All kinds of signs,
For example, the mark of the running result of the previous instruction in the conditional transfer instruction is the basis for whether this instruction is skipped.

(4) External signals. Through the system bus, the control signals outside the CPU can enter the control unit. Such as interrupt request signal and bus request signal.

Output signal:

(1) CPU internal control signals, control the execution of CPU internal components, such as data transmission in registers and registers, modify the value of PC, and complete the control signals of various operations.

(2) Control signals sent to the system bus, such as control bus, memory, and operation of external IO devices.

2. Example for Control Signals 1. The CPU internal bus is not used
Do not use the CPU internal bus:

It does not use the internal bus of the CPU, that is, each component in the CPU is connected separately. Take ADD@X as an example. This addition instruction uses indirect addressing.