On Mon, Apr 25, 2005 at 01:58:17PM +0100, Shahzad Chohan wrote: > I'm a little confused, could someone please help me explain what is a > terminal, what is it for and why do we need it. Why are there > different types of terminals? Also where does the term vt100 or vt102 > fit in to this? Traditionally, a terminal was an actual piece of hardware -- a CRT monitor plus keyboard that connected to a computer via a serial port. The VT100 and VT102 were two such products from Digital. See <http://vt100.net/vt_history> for pictures and more history. As you can see from that page, there's lots of terminals from DEC alone. And there were many others from many different manufacturers. Each of these spoke a slightly different protocol for rendering text on the screen, so Unix computers have means of speaking these different protocols depending on what's connected. Of course, the personal computer revolution basically wiped out the use for such terminals -- now, we just sit at an actual computer system directly. But, for convenience, when a command prompt is wanted, rather than completely reinventing the wheel, the command prompt windows we use actually act quite like the terminals of old, from the operating system's point of view. So, you can have a terminal program which acts to the OS as if it were a VT100 or VT102 -- although connected over a virtual "pseudo terminal" device (see "man pts" if you want more) rather than connected via a real serial port. Usually these days it's more common to emulate "xterm" (actually a terminal type *invented* for a "fake" terminal, the venerable xterm program itself) or to emulate "linux", the console type linux uses for its own virtual text terminals (what you get in runlevel 3, or when you hit ctrl-alt-f1). Make sense? -- Matthew Miller mattdm@xxxxxxxxxx <http://www.mattdm.org/> Boston University Linux ------> <http://linux.bu.edu/> Current office temperature: 71 degrees Fahrenheit.
