Multi-color bit mapped mode is turned OFF by setting bit 5 of 53265 ($D011) and bit 4 at location 53270 ($D016) to a 0. The following POKE does this:
POKE 53265,PEEK(53265)AND 223: POKE 53270,PEEK(53270)AND 239
As in standard (HI-RES) bit mapped mode, there is a one to one cor- respondence between the 8K section of memory being used for the display, and what is shown on the screen. However, the horizontal dots are two bits wide. Each 2 bits in the display memory area form a dot, which can have one of 4 colors.
|BITS||COLOR INFORMATION COMES FROM|
|00||Background color #0 (screen color)|
|01||Upper 4 bits of screen memory|
|10||Lower 4 bits of screen memory|
|11||Color nybble (nybble = 1/2 byte = 4 bits)|
The VIC-II chip supports smooth scrolling in both the horizontal and vertical directions. Smooth scrolling is a one pixel movement of the entire screen in one direction. It can move either UP, or down, or left, or right. It is used to move new information smoothly onto the screen, while smoothly removing characters from the other side.
While the VIC-II chip does much of the task for you, the actual scroll- ing must be done by a machine language program. The VIC-II chip features the ability to place the video screen in any of 8 horizontal positions, and 8 vertical positions. Positioning is controlled by the VIC-II scrolling registers. The VIC-II chip also has a 38 column mode, and a 24 row mode. the smaller screen sizes are used to give you a place for your new data to scroll on from.
The following are the steps for SMOOTH SCROLLING:
|This page has been created by Sami Rautiainen.|
|Read the small print.||Last updated May 12, 2002.|