Re: What is a head ?

[Justin C. <jp...@do...>]

>    Okay I was hoping for more response or ideas. Their seems to be much
> confusion on what a head is and how to handle it properly in Linux. The
> confusion comes out of not knowing what we really need done and what
> things like a head are. It's hard to think of it off the top of your head.  
> I have thought about it and realized the wway to look at it is from a
> historical view point.

Sorry, had Stuff To Do(TM).


>   So you can see that in the days of mainframes multihead was done with
> ttys and their didn't exist the extra devices like their is today. So now
> we have migrated from a terminal to a head. What is the difference? Well a
> head can be though of as a extenstion of a terminal or better yet a
> terminal is a subset of a head. So a head is a place where a person can
> sit down and interface with a machine. The person experiences the
> virtual computer. The computer seems to belong to just him or her. You
> have a bunch of input devices that can manipulated by a single user and
> have a effect on what he/she experiences (usually a video screen). A
> terminal can now be one of these devices alongside other devices such as
> joysticks. Now that we know what a head is the next question is what makes
> a device belong to a head? A device belonging to a head means that data
> goes from the devices attached to that head to be displayed on a device
> attached to that head. In plain english what you do doesn't end up on
> someone elses head. You don't move someone else cursor or display your
> text on their screen. Now we have different types of devices that can be
> attached to a head. A input device or a output device or a device that
> does both. A input device would be a mouse. A output device would be a
> video card or a sound card. A device that does both would be a serial or
> video terminal. Also a device can behave as different types of devices. A
> sound card for example. You might want to have different sound card belong
> to different heads or you might have one sound card and have that piped
> into the entire office. So these are things to think about when it comes
> to the design of this new system.  

Also devices are often virtual now, not physical. For example an xterm is
the equivalent of a display in the old sense, with window focus allocating
one physical keyboard to the virtual keyboard inputs of the different
terminals.

We need to fix the console permissions model, because there are strange
controls on what you can do depending whether you are logged in on a
physical console.

I would also like to see network transparency: I would like for example to
be able to create a head using a keyboard on one machine and a display on
another (yes, so my working environment is particularly odd, but why not).
Hey, why not have a mouse somewhere else again... Moving input devices
should be quite easy with a single event queue model, though again there
are security issues (hey, just imagine someone hacks your box and you
see them actually type rm -rf /).

Justin