First Generation Computers

Vacuum tubes

1940-1956

   First generation computers were those huge machines with many wires and plugs. As we see in many movies from that period of  time, those machines would take space of an entire room. First computers used technology of vacuum tubes powering electronic circuits. ENIAC was the first computer with vacuum tubes build by Presper Eckert and John Mauchly in America in 1946. Vacuum tube is similar to a simple light bulb, thus, it produces heat to powers central processing unit of the first generation type computer. That kind of technology was very energy inefficient, thus very expensive. We can imagine that it would take a lot of light bulbs to produce enough heat to run a computer. Also, vacuum tubes, like regular light bulbs, were very vulnerable, which made the usage even more expensive.  
   As memory, first computers used magnetic drums called like this because they looked like drums. Those devices were first hard disks with maximum capacity of 62.5 kilobytes according to original design of drum memory. The amount of available memory depended on the size. The first mass produced computer, IBM 650 had capacity of 8.5  kilobytes.

   First computers were able to perform only one task at the time because they used the most simple machine language. The machine language was based on punched cards and paper tapes as inputs. So, as we use keyboard or mouse to use computer, at that time, it was piece of paper with holes. Those holes represented certain commands that computer performed. Output, like display in our times,  was in form of a printout. 

   First generation computers were affordable only for big organizations, like census bureau. The amount of heat produced required complex cooling systems. Also, the size did not fit regular apartments. Vulnerability of tubes made first computers even more expensive and time consuming to fix. Also, tubes required great amount of electricity, while first computers performed very slow. Therefore, first type of computers were inefficient and costly for regular people. 

Computer ENIAC with 19.000 vacuum tubes. In case of failure every light bulb had to be examined.  

Most popular computers from vacuum tubes era:

-ENIAC
-EDVAC
-UNIVAC
-IBM 701
-IBM 650

Main characteristics of first generation computers:

Vacuum Tubes:

Triode

Vacuum tubes allowed to create first computers because they are able to strengthen received signal as well as stop and start receiving electrical energy.

Few out of 4000 vacuum tubes supporting IBM 701 used for scientific purposes.

Drum Memory:

Punched Card from 1964:

Even though operating systems were unheard of during the first generation era, those cards were first from of operating system.