5. The principle of computer composition of toad Note five input/output system

5. The principle of computer composition of toad Note five input/output system

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1. Input/output system

1.1 I/O software

(1) I/O instructions

Part of the CPU instruction

(2) Channel instruction

Instructions for the channel itself

1.2 control mode for I/O device and host information transfer1. Program Query Method

2. Program Interrupt mode

Program Interrupt Mode Process

3. DMA Mode

There is a direct data channel between main memory and I/O

No interruption of current procedures

Periodic misappropriation (cycle stealing)

three ways to compare CPU productivity

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5. The principle of computer composition of toad Note five input/output system