Command-level interface (users can issue commands to jobs through this interface to control the running of jobs. This interface is further divided into online user interface and offline user interface)

Program level interface (composed of a set of system function calling commands and program modules that complete these commands)

graphic interface

Processor management (the task of the processor is to run the program, and the process of a program running on a certain data object is called a process, so processor management is also called process management)

Storage management (In a multiprogramming environment, to store multiple programs in memory at the same time, the memory must be reasonably managed to ensure the smooth operation of the program and improve memory utilization) multiple choice questions

Device management

File management

The first generation: the tube era (1946-1955)

Second Generation: The Transistor Era (1955-1965)

Third Generation: Integrated Circuit Era (1965-1980)

The fourth generation: the era of large-scale integrated circuits (1980-present)

Speed, capacity, stability, and reliability have all been gradually and steadily improved!

Manual operation (no operating system) early 1950s

Single-channel batch processing system in the 1950s (can read pictures and recognize)

Multi-channel batch processing system, early 1960s (can read pictures and recognize)

Time-sharing system mid-1960s

interrupt technology

channel technology

Features of time-sharing system (high-performance host, multiple terminals)

real time control

real-time information processing

Single-user multitasking operating system (Win)

Multi-user multi-tasking operating systems (UNIX and Linux)

In a single-processor system, concurrency refers to "multiple programs running simultaneously at the macro level and alternate execution at the micro level"

Resources in a computer system are used by multiple tasks

Microscopically, processes are executed alternately, and the execution, suspension and other states of the process are unpredictable and asynchronous.

Physical entities are mapped into multiple logical entities, and user programs use logical entities

structure

It is a Unix-like operating system that is free to use and freely disseminated.

Types of logical structures

CPU status

memory

Events that cause system interrupts are called interrupt sources

Windows startup process

Operation interface

system call

sequentiality

closedness

Reproducibility

Multiple programs occur simultaneously within the same time interval

discontinuity

lose closure

irreproducibility

ready state

Execution status

blocking state

Process is the basic unit of resource allocation

Thread is the basic unit for allocating processors and has nothing to do with resource allocation.

A thread can only belong to one process, and a process can have multiple threads, but there must be at least one thread

ready state

Operating status

blocking state

priority scheduling algorithm

time slice rotation algorithm

It consists of programs, data, and work instructions

According to processing method

Online jobs (interactive jobs/terminal jobs)

static priority

dynamic priority

Preemptive priority scheduling algorithm

Non-preemptive priority scheduling algorithm

Device initialization

equipment control

Device interrupt handling

System area

user area

Once a region is allocated to a job, the remaining space cannot be used again.

When a job loads memory, if the length of the partition in the memory is less than the length of the job program, the program cannot be loaded.

from front to back

From front to back, connected from front to back

Sort from small to large

Sort from large to small

In paged storage management, main memory is divided into a number of equal-sized physical blocks

The program's address space is divided into logical pages

Logical pages are the same size as physical blocks

Usually the size of the physical block is 2n sectors, such as 1K, 2K, 4K, etc.

The question gives the page size L and the address A of the logical address space. Calculate the page number P and the page address W.

P =(int) [A/L] W=A%L

If the page table is entirely placed in the main memory, fetching one data (or one instruction) requires at least two memory accesses.

Address space protection

access control protection

File system functions

FAT file system

NTFS file system

EXT file system

Source File

Target file

executable file

System Files

Library file

user files

read-only file

Read and write files

executable file

Temporary Files

Archives

permanent file

Ordinary document

catalog file

special document

Access files sequentially according to their logical addresses

For record files, they are accessed sequentially according to the sort order of the records.

Sequential files are files stored sequentially. The order of physical records and the order of logical records are consistent.

Also known as direct access method

It accesses any record in the file according to the record number or address.

For fixed-length record file random access, a file is regarded as a number of numbered blocks or records, and the size of each block is the same.

Random access allows blocks to be read and written to at will. Therefore, there is no defined sequence for random access to files. When an access request is received, the logical address of the record is calculated and then the record is accessed.

For variable-length record files, it is very inconvenient to determine the read and write displacement by calculating the length from the beginning to the specified record. Index table organization is usually used.

Access based on a certain data item value (called a key) in the logical record as an index

The key access method is essentially a random access method

A fixed-length record file means that all records in the file have the same length.

An indefinite-length record file refers to several records in the file that are of different lengths, such as name, home address, notes, etc., which may be longer or shorter.