The Four Generations of Computers

The history of the computer....

What are the four generations of computers?

The first Generation (1945 - 1955)

Very large computers made up of vacuum tubes and often programmed using wiring plug boards.

Programmed using machine language.

Mostly used for numerical calculations as working out mathematical tables

The Second Generation (1955 - 1965)
Mainframes made up of transistors
At first punch cards were used to provide input, then tapes were used (for batch processing)
Used Assemblers and FORTRAN compilers for program writing
Simple batch processing was used with input files, programs and output on tape
Smaller computers (e.g. IBM 1401) was used to read programs and data on punch cards on to input tapes and for offline printing
Used mainly for scientific and engineering applications
FMS (Fortran Monitor System) and IBM IBSYS as OSs for handling jobs (e.g. to read a job and to run it)

The Third Generation (1965 - 1980)

Mainframes based on small scale ICs were used.
Capable of multiprogramming (running several jobs at the same time)
Fixed disks were used and new jobs on cards to be executed could be read on to the disk while executing other jobs (spooling)
Though the first models used multiprogrammed batch processing, to cater to increased response time, timesharing was introduced later (Time-sharing Systems)
Complex OSs as OS/360 were used.
Used for various applications including scientific and business applications
Mini computers also appeared on the market which were used by small departments etc. and became the platform for UNIX.

The Fourth Generation (1980 )
Mainframes, Minicomputers, Workstations, Personal Computers (Desktop and portable) based on VLSI components
Network operating systems that facilitate file sharing, remote logging etc. and Client Server computing.
Distributed OSs that make use of multiple machines and processors to run applications.
GUI based OS interfaces and applications.
Virtual Machines and Network Computers (NCs)

Very New Computers