History of Operating Systems Computers and their operating

History of Operating Systems • Computers and their operating systems have evolved over the years. • Let us fist take a bird’s eye view of the generations of the hardware. Generation Technology 0 Mechanical (Analytical Engine of Charles Babbage) First Vacuum Tubes (mainframes) Second Transistors (mainframes) Third Integrated circuits (IC’s) (mainframes and minis) Fourth LSI and VLSI and PC’s

Generations of the Operating systems • • First generation (1945 -55) – Operating systems were unheard of. – A single group of people designed, built, programmed, operated and maintained each machine. – By the early 1950’s punch cards were introduced to feed programs and data to the computers. Second Generation (1955 -65) – – – Usage of transistors in building the computers made Computers reliable and smaller in size; these machines were called mainframes. But the machines were very expensive; only organizations could afford. programmers used to write programs (in FORTRAN or Assembly language ) on papers and these were punched into special cards readable by the computers. Compilers and assembles were developed. Operating procedure evolved but with lot of human intervention; this wasted a lot of computer’s valuable time Batch system was introduced to save time. Computers were mostly used for scientific and engineering calculations.

Generations of the Operating systems • • • Third Generation (1965 -80) IBM developed System/360 using (small scale) IC’s; the opwerating system OS/360 was developed for this machine. Several key techniques were introduced; these include; – – – Multiprogramming Time sharing Spooling Online documentation Unix was developed for minicomputers

Generations of the Operating systems • • Fourth Generation (1980 - present) Microcomputers (PC’s) were developed Networking gained popularity; network operating systems emerged. Distributed systems emerged and hence distributed Operating systems. WWW and internet emerged Databases gained more importance GUI’s were developed ( first Mac OS X then windows) All Unix systems have GUI’s