INTRODUCTION TO OPERATING SYSTEMS TDC 311

What is an Operating System? It is a provider of services What kind of services?  Creation, support, and termination of threads  Operation of all I/O functions  Support of the file system  Detecting process and system errors and making corrections  Allocating system resources such as memory, the processor, and I/O devices  Support of all accounting functions  Support security operations  Support of network operations

How Does an OS Offer These Services? You click on an icon You type a command line prompt ping You submit a batch job with appropriate JCL //JOB ID=1234,T=3s //EXEC PGM=QSAMCOPY //DD SYSINPUT=RER //DD SYSOUT=DISK3

How Does an OS Offer These Services? From within a higher level language application, you call on an OS function seekp( loc_address, ios::beg); write( &Taken,1); no_records++; $create_proc(&Param1, &Param2, 0, 0);

How Does an OS Offer These Services? From within a lower level language application, you call a macro or subroutine NEXTC6,FULWD BEEQ $CREPROCXVAL,YVAL,0,0 A currently existing OS function calls on another OS function

Types of Operating Systems Mainframe (IBM VM/ESA for IBM 390 systems, Unix, Linux) Personal computers (Windows, MAC OS, Unix, Linux) Local area networks (Windows, Unix, Linux) Distributed systems (Amoeba)  Real-time  Embedded Palm-based systems  PDAs  Cellphones

Actual Operating Systems Think there is only a couple operating systems out there? Think again Look at