Version 2.0 15 Jan-90
CALL SB the SCAN LINE CONTROL BYTE commands
There are 2 commands that control the Scan line Control Bytes (SCB's). A Scan line Control Byte describes the behavior of the pixels for each row of the screen. The screen has 200 rows of pixels that can be either 320 or 640 pixels wide depending on the mode setting.
Figure 2.14 Scan Line Control Byte
Binary is a convienient method to specify scan line control bytes. To set all 200 SCB's to 640 mode graphics use the following program line:
You will usually use palette 0 for all of your needs even though there are 16 palette spots avaliable. It should be noted that specifying a palette that has not been filled by a CALL PL will produce unpredictable results.
A value as described in Figure 2.14.
Top row of the range of SCB's to be set.
Bottom row of the range of SCB's to be set.
Line number of SCB to read.
Returned value ... must be an Applesoft FP (real) variable.