Download TDC 311 - DePaul University

TDC 311
INTRODUCTION TO OPERATING SYSTEMS
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 138.54.101.1
 You submit a batch job with appropriate JCL
// JOB
ID=1234,T=3s
// EXEC
// DD
// DD
PGM=QSAMCOPY
SYSINPUT=RER123.56
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
NEXT
BE
$CREPROC
C
6,FULWD
EQ
XVAL,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 http://tunes.org/Review/OSes.html