Hỏi Con 5s Essay

2617 words - 11 pages

Part 1
Introduction
1.1 What is an operating system
1.2 History of operating systems
1.3 Computer hardware review
1.4 The operating system zoo
1.5 Operating system concepts
1.6 System calls
1.7 Operating System Structure
1

1.1 What is an operating system

2

What is An Operating System
A modern computer consists of:




One or more processors
Main memory
Disks
Printers
Various input/output devices

Managing all these components requires a layer of
software – the operating system
3

What is an Operating System

4

The Operating System as an Extended Machine
- Hides the messy details which must be performed
- Presents user with a virtual ...view middle of the document...

x
1995: Window 95
1996: Window NT 4.0
1999: Window 2000
Window 2003
Unix

16

1.3 Computer Hardware Review

17

Computer Hardware Review



CPU
Memory
I/O Devices
Buses

18

Computer Hardware Review
Monitor

Bus

• Components of a simple personal computer
19

Computer Hardware Review
The CPU (1)







PC Program Counter
SP Stack Pointer
PSW Program Status Word
General Registers
Instruction Cycle
Pipeline
Superscalar
System Call
20

Computer Hardware Review
The CPU (2)

21

Computer Hardware Review
The CPU (3)

(a) A three-stage pipeline
(b) A superscalar CPU
22

Computer Hardware Review
The CPU (4)

23

Computer Hardware Review
The CPU (5)
• Dual-mode operation allows OS to protect
itself and other system components
– User mode and kernel mode
– Mode bit provided by hardware
• Provides ability to distinguish when system is
running user code or kernel code
• Some instructions designated as privileged, only
executable in kernel mode
• System call changes mode to kernel, return from call
resets it to user
24

Computer Hardware Review
The CPU (6)
• Transition from User to Kernel Mode

25

Computer Hardware Review
Memory (1)

• Typical memory hierarchy
– numbers shown are rough approximations
26

Computer Hardware Review
Memory (2)
• Storage systems organized in hierarchy.



Speed
Cost
Size
Volatility

27

Computer Hardware Review
Memory (3)
Registers:
• Small number, Fast
• Capacity:
– X*32 bit on 32-bit CPU
– Y*64 bit on 64-bit CPU

28

Computer Hardware Review
Memory (4)
Caching – copying information into faster
storage system; main memory can be
viewed as a last cache for secondary
storage.

29

Computer Hardware Review
Memory (5)
Caching
• Important principle, performed at many levels in a
computer (in hardware, operating system, software)
• Information in use copied from slower to faster storage
temporarily
• Faster storage (cache) checked first to determine if
information is there
– If it is, information used directly from the cache (fast)
– If not, data copied to cache and used there

• Cache smaller than storage being cached
– Cache management important design problem
– Cache size and replacement policy

30

Computer Hardware Review
Memory (6)
Main Memory




RAM (Random Access Memory)
Problem:
– How protect the program from one another and the kernel from
them all
– How to handle relocation
Solution: CPU equipped with two special registers
Base Register and Limit Register
MMU (Memory Management Unit) convert Virtual Address to
Physical Address
Context Switch; switching from one to another

31

Computer Hardware Review
Memory (7)
Relocation and Protection
• Cannot be sure where program will be loaded in memory
– address locations of variables, code routines cannot be absolute
– must keep a program out of other...

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