- 2067 Asar (old course) · 4 marks
Types of I/O commands
Short answer
The four I/O commands are: control to activate and direct the peripheral, status to test conditions like ready or busy, data output to write data from the bus to the device, and data input to read data from the device into the interface buffer.
What are the four types of I/O commands that an interface receives during the communication link between the processor and peripherals?
When the processor communicates with a peripheral through the interface, the interface can receive four types of I/O commands:
- Control command: activates the peripheral and tells it what to do (for example rewind a tape, move the disk head, start a motor).
- Status command: tests the conditions of the interface and the device (ready, busy, error) before a transfer begins and after it finishes.
- Data output command: makes the interface take a word from the data bus and send it to the peripheral (a write).
- Data input command: makes the interface take a word from the peripheral and place it in its buffer register so that the processor can read it from the data bus (a read).
✓ Answer checked by Claude Opus 5.5 (high effort)
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