Match List I with List II. List I: A. Handshaking, B. Programmed I/O, C. Interrupt-initiated I/O, D. I/O processor. List II: I. I/O interface informs the CPU that the device is ready for transfer, II. Requires two control signals working in opposite directions, III. Has local memory and controls a large set of I/O devices, IV. Requires the CPU to check the I/O flag and perform the transfer.

1. AA-I, B-II, C-III, D-IV
2. BA-II, B-IV, C-III, D-I
3. CA-II, B-IV, C-I, D-III
4. DA-IV, B-III, C-II, D-I 3 × 3

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Correct answer: C. A-II, B-IV, C-I, D-III

Explanation

Handshaking uses two control signals in opposite directions; programmed I/O has the CPU polling the flag; with interrupts, the interface tells the CPU it is ready; an IOP has local memory and runs many devices.