DAC

DAC stands for the QBasic Digital to Analog Converter color attributes used in screens 0, 7 and 9.

** IMPORTANT: QB64 screens do not use the DAC index!**

• DAC colors are preset and cannot be changed in QBasic easily(see example).
• DAC color attribute settings cannot be changed using PALETTE or OUT RGB statements.
• Screen 0 and 9 can use up to 64 DAC color hues. Only attributes 0 to 5 and 7 can have RGB values altered using OUT.
• PALETTE swap statements can assign one attribute's DAC color setting to another attribute color in SCREENs 0 to 9.
• Screen attributes 0 to 5 and 7 can have their RGB settings altered using OUT as shown in Bold below:

            ***SCREEN 0 or 9                     SCREEN 7***
        Attribute = DAC setting         Attribute = DAC setting
          ** 0 to 5 = 0 to 5                 0 to 5 = 0 to 5**
                6 = 20                       **   6 = 6**
                7 = 7                           7 = 7**
                8 = 56                          8 = 16
                9 = 57                          9 = 17
               10 = 58                         10 = 18
               11 = 59                         11 = 19
               12 = 60                         12 = 20
               13 = 61                         13 = 21
               14 = 62                         14 = 22
               15 = 63                         15 = 23

    **OUT can change RGB intensities where the DAC value matches the attribute value.**

Changing the DAC attributes to use OUT for custom colors.

SCREEN 9   'use 0, 7 or 9 only"
InitDAC% = INP(&H3DA)    ' prepare DAC port for access
FOR attribute% = 6 TO 15 ' attributes 0 to 5 are already non-DAC
   OUT &H3C0, attribute% ' send attribute to change
   OUT &H3C0, attribute% ' change DAC value to normal number
NEXT attribute%"
OUT &H3C0, 32            ' close port access

Explanation: The procedure is a MUST to import 4 BPP bitmap colors in SCREEN 7 or 9. The InitDAC% value is not used, but that code line opens the DAC color port. Now all color attributes 0 to 15 can be used for custom or imported bitmap RGB color settings.

Disabling blinking colors in fullscreen SCREEN 0 mode enabling high intensity only. (DAC)

D = INP(&H3DA)    'prepares port for access
OUT &H3C0, &H30 
OUT &H3C0, 4 

Explanation: Make attributes 8-15 available to both foreground AND background colors. In other words it will make fullscreen behave like windowed mode. For the same effect in QB64, use _BLINK OFF.

Enabling: The following code disables above code and returns SCREEN 0 blinking to normal.

D = INP(&H3DA)    'prepares port for access
OUT &H3C0, &H30 
OUT &H3C0, 12 

NOTE: QB64 allows blinking mode in both fullscreen and windowed modes without using the code above. To reenable blinking in QB64 after using _BLINK OFF, use _BLINK ON.

See Also

• SCREEN (statement), COLOR
• PALETTE