CGS 3763 Operating Systems Concepts Spring 2013 Dan C. Marinescu Office: HEC 304 Office hours: M-Wd 11:30 - 12:30 AM

Lecture 4 – Monday, January 14, 2013 Last time: State and events; Event-driven-software Discussion of problems from the textbook Today: Types of systems User access; user interfaces OS services The management of computer resources: CPU, memory, I/O devices Next time Protection – user and kernel mode execution System calls Kernel data structures Reading assignments: Chapter 2 of the text book The computer architecture material 11/30/2018

Questions Why there are different types of operating systems? Why do we need to distinguish the mode in which an OS and an application run? What is a process? What is a thread? Why do we need to share the CPU of a system among multiple processes/threads? What do we mean by a memory hierarchy? Why do we need a hierarchy of memory? What is virtualization? What is virtual memory? What is an interrupt? What types of interrupts can you identify? 11/30/2018

User-computer relationship Many-to-one  time-shared systems One-to-one  PCs One-to-many  Computational grids, network computers Many-to-many  Computing clouds Different resources and OS for each class of systems 11/30/2018

Kernel functions Program execution: Interrupt handling: Error handling: Job sequencing: Input/Output operations: File system manipulation: Scheduling: Resource Allocation: Accounting of computer resources: Protection: 11/30/2018

Management of system resources Processor Memory hierarchy I/O devices 11/30/2018