1. Introduction, Operating System History

Evolution of Operating Systems

• In the begining, one user at a time, working directly at console
• Phase 1
  • Hardware expensive, humans cheap
  • First OS: I/O subroutine libraries shared by users
  • Simple batch monitor: get user away from the computer. OS = program to load and run user jobs, take memory dumps after crashes
  • Overlap of I/O and computation: data channels, interrupts
  • Memory protection and relocation enable multitasking: several users share the system
  • OS must manage interactions, concurrency
  • By mid-1960's operating systems had become large, complicated
  • OS filed emerges as important discipline with principles
• Phase 2
  • Hardware cheap, humans expensive
  • interactive timesharing - File systems, Issues of response time, thrashing
  • Personal computers: computers are cheap, so put one in each terminal
  • Networking: allow sharing and communication between machines
  • Personal devices: put computers in cell phones, stereo players, TVs, light switches
• Phase 3 (recent years)
  • Very small (devices), very large (datacenters, cloud)
• Most of an operating system's functions have to do with managing shared resources efficiently:
  • Concurrency: allow several different tasks to share processors, each appears to have a private machine. To keep track of everything, processes and threads were invented
  • Memory: how can a single memory be shared among several processes?
  • I/O devices: manage basic operations efficiently (e.g. many devices can be operating concurrently). Manage shared resources such as network interfaces
  • Files: allow many files, for many different users, to share space on the same storage devices (disk/flash)
  • Networks: allow groups of computers to work together
  • Security: how to allow interactions while protecting each participant from abuse by the others?
• Characteristics of current OSes
  • Enormous: millions of lines of code, 100-1000 engneer-years
  • Complex: asynchronous, hardware idiosyncrasies, performance is crucial
  • Poorlly understood

 

 

Summary

 

- 시간에 따라 OS가 발전했다.

- 하드웨어의 가격도 싸졌다.

- 공유 자원을 어떻게 효과적으로 관리할 것인지가 OS의 핵심이다.

 

 

정리가 잘 돼 있어서 받아쓰기만 하게 되네요.