Question

Microprogrammed control unit uses fixed logic to interrupt instruction.

True or False.

Comments

it should be false ...

we uses microprogrammed control unit so that we can have a flexibility over CONTROL signals and execution...

ONLY in case of hardwired ..we have fixed logic ...but for Microprogramming ..we can have flexiblity..

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@Shubham, how would you relate this to interrupting instruction?

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I think False because microprogrammed  control unit uses flexible logic.

Answer 1

In microprogrammed control unit, the logic of the control unit is specified by a microprogram.

As we are using a program to generate control signals no fixed logic is required.

For hardwired CU 

Hardwired control units are implemented through use of combinational logic units, featuring a finite number of gates that can generate specific results based on the instructions that were used to invoke those responses. Hardwired control units are generally faster than microprogrammed designs.[4] Their design uses a fixed architecture—it requires changes in the wiring if the instruction set is modified or changed. This architecture is preferred in reduced instruction set computers (RISC) as they use a simpler instruction set

Ref: http://nptel.ac.in/courses/106103068/21

https://en.wikipedia.org/wiki/Control_unit#Hardwired_control_unit

Answer 2

The statement is False.

In a microprogrammed control unit, the control signals for instruction execution are stored in a control memory (often a ROM or PLA) in the form of microinstructions. These microinstructions are typically fetched sequentially, and each microinstruction provides control signals for executing a specific step of an instruction.

The term "microprogramming" refers to the use of a sequence of microinstructions to control the execution of machine instructions. The control memory stores the microinstructions, and the control unit fetches and executes them in sequence.

The idea of a microprogrammed control unit is that the control signals for each machine instruction are stored in a microprogram, and the control unit interprets and executes this microprogram.

The use of fixed logic, on the other hand, typically refers to hardwired control units where the control signals are generated directly by combinational logic circuits. In fixed logic, there is no control memory storing microinstructions; instead, the control signals are generated based on the opcode of the instruction.

In summary, microprogrammed control units use a control memory to store and fetch microinstructions, providing a more flexible and easily modifiable control strategy compared to fixed logic.