Outline of topics covered 4/19/96

Examples of current operating systems:

	DOS, Windows, Unix

HISTORY OF OPERATING SYSTEMS

-- computer cost millions of dollars --  had to be shared --

Burroughs 220 (last vacuum tube machine) (1963)
	cards/paper tape input
	debugged programs with console switches
	machine sat idle 
		while debugging
		between jobs
		between users
	essentially no operating system

Earliest operating systems
	essentially a monitor program to read in on job
	 right after another.
	minimized idle time between jobs.

Early batch operating systems
	(even with monitor, lots of computer time wasted
	 waiting for slow I/O to/from cards readers and printers.)
	Auxiliary machine copies batch of jobs from card reader to tape
	Tape taken to computer.
	Jobs run one after another from tape with output written to tape
	Tape taken to auxiliary machine
	Auxiliary machine copies output on tape to printer.

Multiprogramming
	several programs run at the same time.  Occupy different parts
	 of memory.  Processor shared among programs

SPOOLing (Simultaneous Peripheral Operation On Line)  Batch like system.
	disk replaces tape.  Auxiliary machines replaced by spooling
	 programs in memory run in multiprogramming mode.

-- Large Computer Facilities -- Users don't touch computers --

IBM System 360 (1965)
	System 360 was a spooling system
	Duke ran it trough Triangle Universities Computation Center (TUCC)
	 located in RTP.  Jobs sent out there through telephone lines.
	 (This communication process was then called teleprocessing)

Time Sharing
	A multiprogramming system where multiple users jobs were in
         memory at the same time.  The processor was shared among the
         programs so each user thought they had the machine to themselves.
	 Many additional users were able to "simultaneously" use
	 machine by having user's programs swapped to disk when it
	 was idle.  Users usually accessed jobs through low-speed
	 terminal (such a teletype machines) over phone lines and slow
	 modems. (110 - 300 bits/second typical) [Now 14400 - 28000 bits
  	 /second typical]
	
	Time sharing services were provided by System 360.

-- Computer Get Cheaper -- Lab Computers --

Minicomputers (1970's)
	Lab computers costing only around $100,000 became available
		Digital Equipment Company made its mark

		UNIX designed at Bell Laboratories
			supported multiple users
			more hands on

Microprocessor (computer on a chip)  Intel

	Hobbyists get into the personal computer game/build their own

IBM introduces the IBM PC (Intel 8088 processor)  (1980's)
	legitimizes the personal computer movement for business
	adopts "open architecture"   
		many different vendors make equipment for PC
		eventually many different vendors make PC clones.

Operating System for Personal Computers | Apple
	DOS 				|
	UCSD Pascal			| Macintosh
	OS/2				|
	Windows				|	ease of use
	Xenix (UNIX adapted to PC)	|

	These operating systems did many of the things that the
	 big operating systems like System 360 did.

Computer Workstations (1990's)
	High Power
	High Resolution Graphics
	typically UNIX

	Sun Microsystems and others