UNIX PC Graphics Questions

[Alex S. Crain]

In article <700 at naucse.UUCP> rrr at naucse.UUCP (Bob Rose ) writes:
>In article <267 at uncle.UUCP>, jbm at uncle.UUCP (John B. Milton) writes:
>> In article <2271 at inco.UUCP> todd at inco.UUCP (Todd O'Connell) writes:
>> > [Is there any way to directly access screen memory?]
> 
>> The UNIXpc screen memory is located at $420000, and the only way to access
>> that area of memory would be through a loadable driver. This kind of access
>> would screw up the window manager's view of things.
>
>What about opening `/dev/mem' for reading and writing.
>Note, I'm note responsible if you miss the screen and hit
>the drive controller crashing your hard disk.

	It is easier to load a device driver that to do io to /dev/mem, and
/dev/mem carries ALL of the dangers of device drivers. Be warned that playing
with device drivers can do more damage than simply crashing the machine, a 
friend of mine thinks that he wrote over the partition table on his hard
drive, ther wasn't enough left to be sure. If you want to play with this,
PLEASE know what you are doing.

	On this train of thought though, Does anyone know how works the 
keyboard controller? and does the mouse do its work through the controller
registers, or is that different? If one of the folks with a hardware manual
could breifly explain it, I would be most appreciative.

	For those interesed in poking the video memory, look in <sys/iohw.h>
-- 
					:alex.

nerwin!alex at umbc3.umd.edu
alex at umbc3.umd.edu