OS development and classification
Manual stage
Tape punching machine
disadvantages
The user monopolizes the whole machine, the man-machine speed contradiction leads to the use efficiency is very low
Batch stage
Single channel batch system
The principle of
Offline I/O technology (done on tape), and the supervisor is responsible for controlling the input and output of the job
disadvantages
There is only one program running in the memory, and the next program can be called only after the program runs. The CPU has a large amount of idle time waiting for I/O completion, resulting in low resource utilization
Multichannel batch system
The principle of
Enter multiple programs into memory at a time
advantages
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Multiple programs execute concurrently, sharing computer resources. Substantial increase in resources
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A phase in which CPU and other resources remain busy and throughput increases
disadvantages
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The user response time is long
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There is no human-computer interaction
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Users can only wait for the program to finish execution, not control their own job execution
Time-sharing operating system
The principle of
The time slice is unit in turn for each user/job service, each user can interact with the computer through the terminal
advantages
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Instant response
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It has man-machine interaction function
disadvantages
There is no priority processing, which is fair to all programs
Real time operating system
advantages
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Ability to prioritize urgent tasks
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Events can be processed within tight deadlines
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Timeliness and reliability
classification
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Hard real-time systems: processing must be done within absolutely strict rules
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Soft real-time system: can accept the occasional time violation