操作系統(tǒng)原理緒論(英文課件)-文庫(kù)吧
2024-11-23 09:40 本頁(yè)面
【正文】 ? Manage system resources to make them utilized and shared effectively. ? Organize puter’s workflow reasonably in order to improve system performance (response time /throughput). ? Provide user interfaces to simplify user operations. (Convenience、 Efficiency、 Scalability、 Open) Abstract View of System Components Virtual machine 裸機(jī)在每增加一層軟件后，就成為一個(gè)功能更強(qiáng)的機(jī)器，通常將這個(gè)“新的功能更強(qiáng)的機(jī)器”稱為 “ 虛擬機(jī) ” Chapter 1: Introduction ? What is an Operating System? ? History of Operating Systems ? The Operating System Zoo History of Operating Systems ? First generation 1945 – 1955 ? vacuum tubes, plug boards (no OS) ? Second generation 1955 – 1965 ? transistors, batch systems ? Third generation 1965 – 1980 ? ICs, multiprogramming ? Fourth generation 1980 – present ? personal puters, handheld devices, sensors First Generation 1945 – 1955 ? OS: none (programs were entered by setting some switches) ? Computer designer is: builder, programmer, operator, and “sys admin” ? A physicist who wanted to calculate the trajectory of a missile would sign up for an hour on the puter in advance. ? When his time came, he would e into the room, feed in his program from punched cards or paper tape, watch the lights flash, maybe do a little debugging, get a printout, and leave. ENIAC (Electronic Numerical Integrator And Computer) ? It contained 17,468 vacuum tubes, weighed 30 short tons (27 t), and took up 680 square feet (63 m178。), and consumed 150 kW of power. ? Input was possible from an IBM card reader, and an IBM card punch was used for output. ? No programming language, let alone OS Punched Card A Famous Remark ! I think there is a world market for maybe five puters. Thomas Watson, chairman of IBM, 1943 Second Generation 1955 – 1965 ? Universities started to buy puters (spending millions of dollars) ? OS: batch system ? Programming language: FORTRAN amp。 Assembly ? Computer: Mainframes ? Low CPU utilization slow mechanical I/O devices IBM STRETCH DEC PDP1 Early Batch System ? bring cards to 1401 ? read cards to tape ? put tape on 7094 which does puting ? put tape on 1401 which prints output Batch Systems ? Hire an operator 設(shè)置一個(gè)操作員 ? User ? operator ? Reduce setup time by batching similar jobs 批量處理同類作業(yè)減少了設(shè)置時(shí)間 ? OS’s main task: Automatic job sequencing – automatically transfers control from one job to another. ? Resident monitor ? initial control in monitor 初始化管理程序 ? control transfers to job 轉(zhuǎn)換控制到作業(yè) ? when job pletes control transfers back to monitor 作業(yè) =程序 +數(shù)據(jù) +處理步驟 Memory Layout for a Simple Batch System Control Cards ? Problems 1. How does the monitor know about the nature of the job (., Fortran versus Assembly) or which program to execute? 2. How does the monitor distinguish (a) job from job? (b) data from program? ? Solution ? Introduce control cards Control Cards (Cont.) ? Special cards that tell the resident monitor which programs to run $JOB $FTN $RUN $DATA $END ? Special characters distinguish control cards from data or program cards 特定的字符把數(shù)據(jù)卡片和程序卡片區(qū)分開來(lái) Structure of a typical Fortran Monitoring System job $JOB card specifies: ? the max runtime in minutes ? The account number to be charged ? The programmers name
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