In programationWhen programming, the raster is often referred to as the act to modify of modifying the setting of inks between 2 scanlines, in interrupt mode.
This is a way to display more than the usual [[Video modes]] number of colours.
The time between the display of 2 Scanlines by the CRTC allow the CPU to order the Gate array to modify the setting of inks.
The screen display at is updated with a frequency of 50Hz...The [[CPU]] ([[Z80]]) runs at about 4 MgHzMHz.
So It has enough cycles between 2 scanlines to order this.
You can also use Split raster to "actually" display 2 different screens, sometimes with different Video Modes. This also allows a Graphic heavy [[HUD]] with no interference with [[Scrolling]].
==Links==
*[http://en.wikipedia.org/wiki/Raster Wikipedia link to Raster concepts]
*[[Synchronising with the CRTC and display]]
*[[Programming:Simple Raster Example 1]]