From the user's standpoint, how he interacts with the computer is an issue surpassingly more important than what the computer is built from. The very way in which the user perceives the computer (his mental model of it), the degree to which specialised knowledge and extensive training are required to use it, and therefore the extent to which the computer becomes accessible to a very broad segment of the populace is largely controlled by the means through which the user operates the computer. Let's try to redefine computer generations in terms of modalities of operation.
| Generation | Means of operation |
|---|---|
| First | Plugboards, dedicated setup |
| Second | Punched card batch, RJE |
| Third | Teletype timesharing |
| Fourth | Menu systems |
| Fifth | Graphical controls, windows |