A frame buffer graphics device
is an idealization
of your computer
's video hardware
in order to make programming
it simple. It simulates
or provides in actual memory
a space which maps to the screen byte
for byte (or word
for word, or 32 bit longword
for longword), in such a way that the data
0 stands for the pixel
(0,0), and so on until the end of line 0 (which has, for example, 1024 pixels), so that byte 1024 represents (0,1), etc.
This makes creating
easy, since you only have to allocate
and write to a memory block
of the same size as the frame buffer, and then copy the off- screen buffer into the frame buffer.
Frame buffer devices may fulfill more complex
tasks, but the thing here is the minimum.