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OUT writes values to register and port hardware addresses.



OUT registerAddress%, value%


  • registerAddress% is a value expressed as a decimal INTEGER or hexadecimal.
  • The INTEGER value% sent is normally only 0 to 255 per byte register (8 bit) address.


  • QB64 has limited access to registers. VGA memory and registers are emulated.
  • OUT can be used to change color port and a limited number of other port settings in QB64.
  • Some settings may be set in a specific order to gain access to settings and INP reads.
  • SCREEN modes determine the number of available color palette attributes from 2 to 256 in SCREEN 13.
  • Windows NT may block access to Parallel printer and Serial ports. See Port Access Libraries or other DLLs.
  • _PALETTECOLOR can also be used to set RGB intensity values using 32 bit color values.
  • OUT can toggle the blinking attribute of SCREEN 0 color 16-31 for legacy code. _BLINK is the preferred method. (starting with build 20170816/61).

Color Port Palette access using OUT

OUT &H3C7, attribute : Set port to read RGB settings for start attribute
INP &H3C9, colorIntensity : Reads RGB color intensity settings in order
OUT &H3C8, attribute : Set port to write RGB settings for start attribute
OUT &H3C9, colorIntensity : Writes RGB color intensity settings in order
  • Every 3 reads or writes, changes to next color attribute without a set
  • Color setting is Red, Green and Blue attribute intensities in order.
  • Color attribute intensity values range from 0 to 63.
  • Some DAC color attribute intensities cannot be changed using OUT.


  • In DOS, OUT accesses memory and hardware directly, unlike POKE, and could cause PC damage.


Example 1: Reading the default RGB color settings of color attribute 15.

OUT &H3C7, 15 'set color port attribute 15 for a read red% = INP(&H3C9) green% = INP(&H3C9) blue% = INP(&H3C9) PRINT red%, green%, blue%

63 63 63

Example 2: Changing the color intensity settings of the SCREEN background COLOR 0 to bright white.

OUT &H3C8, 0 'attribute number. 0 for black screen background OUT &H3C9, 63 'red OUT &H3C9, 63 'green OUT &H3C9, 63 'blue

Explanation: In SCREEN 0 this is one way to make high intensity background colors. COLOR ,15 is actually grey (7).

Example 3: Toggling blinking colors in SCREEN beginning with build 20170816/61

OUT &H3C0, &H10 'disables blinking and enables high intensity backgrounds (colors 16-31) OUT &H3C0, 2 ^ 3 'reenables blinking and disables high intensity backgrounds (colors 16-31)

Note: In QB64, the recommended practice is to use the _BLINK {ON|OFF} statement.

Example 4: Restoring colors to a bitmap from the Red, Green and Blue BSAVEd indexed array of color values.

SCREEN 12 OUT &H3C8, 0 ' set color port for output at attribute 0 FOR i = 0 TO 47 ' 48 RGB values is (3 * 16) -1 color attributes from 0 in screen 12 OUT &H3C9, Image%(i) ' changes to next attribute after 3 RGB loops NEXT PUT(clm, row), Image(48) PSET

Explanation: The color RGB intensity settings were imported from a file to the Image array using BLOAD. The color attribute advances to the next one every 3 writes using OUT. The color information was indexed to the start of the array. The image is after the color settings at index 48. Index 48 is the GET image width and 49 is the height.

See also

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