1.2.1. Stone Age

In 1940s, computers were built by Howard Aiken at Harward University, John von Neumann at Princeton University, and others. The computers used relays or vacuum tubes, the former notoriously unreliable, the latter plagued with power consumption and heat generation. The computers were used to perform specialized calculations, which were initially programmed, or, rather, wired into the computer using plug boards. Plug boards were later replaced by punch cards or paper tapes. There was no notion of an operating system.

HardwareYearSoftware
Mark I or Automatic Sequence Controlled Calculator - a computer developed by IBM and Harward University, uses relays, program stored on paper tapes, a multiplication operation takes 6 seconds, a division operation takes 12 seconds. 1944  
Electronic Numerical Integrator And Computer (ENIAC) - a computer developed by University of Pennsylvania, uses vacuum tubes, program stored on plug boards, a division operation takes 25 miliseconds. 1946  
Selective Sequence Electronic Calculator - a computer developed by IBM, uses relays and vacuum tubes, program stored on paper tape and in internal memory, a multiplication operation takes 20 miliseconds, a division operation takes 33 miliseconds. 1948  
Electronic Delay Storage Automatic Calculator (EDSAC) - a computer developed by University of Cambridge, uses vacuum tubes, program stored on paper tape and in internal memory, a multiplication operation takes 4.5 miliseconds, a division operation takes 200 miliseconds. 1949  
Electronic Discrete Variable Automatic Computer (EDVAC) - a computer developed by University of Pennsylvania, uses vacuum tubes, program stored on magnetic wires and in internal memory, multiplication and division operations take 3 miliseconds. 1951  

References. 

  1. Weik M. H.: The ENIAC Story. http://ftp.arl.mil/~mike/comphist/eniac-story.html

  2. The Columbia University Computing History Website. http://www.columbia.edu/acis/history

  3. The Manchester University Computing History Website. http://www.computer50.org

  4. The EDSAC Website. http://www.cl.cam.ac.uk/UoCCL/misc/EDSAC99