• 1.1 what is an operating system? • 1.1.1 the operating system as an extended
machine[※※※※]
– Hides the messy details which must be performed – Presents user with a virtual machine, easier to use,
• The distinction between kernel mode and user mode, however, is sometimes blurred in embedded systems and some other systems
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What is an Operating System
machines, the operation of the data path is controlled by software, called the micro-program
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Machine language
• Machine language (instruction set architecture) it consists of:
• 1.2.3 Third generation (1965-1980) ICs (integrated circuits )and multiprogramming
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现代 操作 系 统
引论
• 1.1 什么是操作系统 • 1.2 操作系统发展史 • 1.3 操作系统大观 • 1.4 计算机硬件概述 • 1.5 操作系统概念 • 1.6 系统调用
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Introduce
• A computer system consists of:
– hardware – system programs – application programs
• Micro-architecture level: in which the physical devices are grouped together to form functional units, this level consists of:
– Registers internal to the CPU – A data path containing an arithmetic logic unit: on some
• 1.2.2 Second generation (1955-1965) Transistors and batch systems
– Typical OS:FMS(the Fortran monitor system) and IBSYS (IBM’s operating system for the 7049);
• Tholled by loading values into special device registers
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User mode and kernel mode
• Kernel mode (supervisor mode): [※※※※]
– The programs in it can be protected from user tampering by the hardware
– The operating run in it
• User mode: [※※※※]
– Compilers and editors run in user mode – If a user does not like a particular compiler, he is free to
write his own
Introduce
• 1.1 What is an operating system • 1.2 History of operating systems • 1.3 The operating system zoo • 1.4 Computer hardware review • 1.5 Operating system concepts • 1.6 System calls
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History of Operating Systems
• 1.2 history of operating systems
• 1.2.1 First generation (1945-1955) vacuum tubes, plug boards
– Operating system were unheard of
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Physical devices and micro-architecture level
• Physical devices consists of :
– Integrated circuit chips – Wires – Power supplies – Cathode ray tubes, and so on
– The hardware – Instructions visible to an assembly language programmer
• The function of machine language:
– Moving data around the machine – Doing arithmetic – Comparing values
Hide the truth about the hardware from programmer
• 1.1.2 the operating system as a resource manager[※※※※]
– Each program gets time with the resource: Different programs take turns to use resource – Each program gets space on the resource: Each get parts of the resource