[CentOS] how does the bootup screen move the cursor around?

Bart Schaefer barton.schaefer at gmail.com
Sat Mar 20 17:34:48 UTC 2010


On Fri, Mar 19, 2010 at 10:18 PM, Frank Cox <theatre at sasktel.net> wrote:
> My question is, how does that happen?  Does it write its own esc codes
> directly to the screen?  If so, how does it know what terminal we're
> using and, therefore, what esc codes to send?

Modern "terminals" aren't text-based devices like the ones that used
to be connected as serial consoles on old refrigerator-sized
"mini-computers" and mainframes.  Instead they're effectively
framebuffer devices and anything that looks like text-character
drawing is done by the display chipset on the graphics card or built
into the motherboard.  Those in turn all have a common set of minimal
operations that can be accessed before the full set of OS-level
drivers is loaded and that are supported by all types of monitors, so
the boot loader doesn't need to know what specific chipset or monitor
you have available as long as the basic hardware is considered
supported.


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