User talk:GABRIEL GERMAN

1 Fall 1998, Lecture 01 What is an Operating System? n An operating system (OS) is the interface between the user and the hardware l It implements a virtual machine that is easier to program than bare hardware n An OS provides standard services (an interface) which are implemented on the hardware, including: l Processes, CPU scheduling, memory management, file system, networking n The OS coordinates multiple applications and users (multiple processes) in a fair and efficient manner åThe goal in OS development is to make the machine convenient to use (a software engineering problem) and efficient (a system and engineering problem) 2 Fall 1998, Lecture 01 Why Study Operating Systems? n Abstraction — how do you give the users the illusion of infinite resources (CPU time, memory, file space)? n System design —tradeoffs between: l performance and convenience of these abstractions l performance and simplicity of OS l functionality in hardware or software n Primary intersection point — OS is the point where hardware, software, programming languages, data structures, and algorithms all come together n Curiosity — “look under the hood” n “Operating systems are among the most complex pieces of software yet developed”, William Stallings, 1994 3 Fall 1998, Lecture 01 Modern OS Functionality n Concurrency l Multiple processes active at once l Processes can communicate l Processes may require mutuallyexclusive access to some resource l CPU scheduling, resource management n Memory management — allocate memory to processes, move processes between disk and memory n File system — allocate space for storage of programs and data on disk n Networks and distributed computing — allow computers to work together n Security & protection 4 Fall 1998, Lecture 01 What is an Operating System? n A magician — provides each user with the illusion of a dedicated machine with infinite memory and CPU time n A government — allocates resources efficiently and fairly, protects users from each other, provides safe and secure communication n A parent — always there when you need it, never breaks, always succeeds n A fast food restaurant — provides a service everyone needs, always works the same everywhere (standardization) n A complex system — but keep it as simple as possible so that it will work