Question

Match List-I with List-II.

List-I	List-II
A. Registers	I. Ready by the host to get input
B. Control Register	II. Written by the host to send output
C. Status Register	III. Contains bits that can be read by the host
D. Data-in Register	IV. Can be written by the host to start a command

Choose the correct answer from the options given below:

• A. A-IV, B-III, C-I, D-II
• B. A-III, B-IV, C-II, D-I
• C. A-I, B-II, C-III, D-IV
• D. A-II, B-I, C-IV, D-III

Hint:

Control register → commands, Status register → state, Data register → data flow.

Answer 1

The Correct Option is B

Concept: Registers in I/O systems are used for communication between CPU and devices.

Step 1: Understand Registers. Registers generally:
• Store temporary data
• Can be read by host \[ A \rightarrow III \]

Step 2: Control Register.
• Used to send commands to device
• Written by host to initiate operations \[ B \rightarrow IV \]

Step 3: Status Register.
• Provides information about device status
• Host reads these bits \[ C \rightarrow II \]

Step 4: Data-in Register.
• Used when data is received from device
• Ready for host input \[ D \rightarrow I \]

Step 5: Final mapping. \[ A-III,\ B-IV,\ C-II,\ D-I \] \[ \boxed{(2)} \]