Functioning of video controller of the Raster scan systems

Question

Define and illustrate the functioning of the video controller of the Raster scan systems?

Answer 1

a) It is a fixed region of the system memory is reserved for frame buffer and the video controller is provided access to the frame-buffer memory.

b) Tow registers are employed to store the coordinates of screen pixels.

c) The value stored in the frame buffer for this pixel place is then retrieved and utilized to set the intensity of CRT beam.

d) At first x register is set up to 0 and y register is set up to ymax

e) Then the x register is raised by 1, and the procedure repeated for the subsequent pixel on the top scan line.

f) This procedure is then repeated for each and every pixel all along the scan line.

g) After that the last pixels on top scan line has been processed, then the x register is reset to 0 and the y register is reduced by 1.

h) The procedure is recurring fro for all successive line.