Display file format

DISPLAY and function-key help files are text files in either DOS or UNIX format (i.e. with or without <CR>).
See also IsoLinux Mate to help with writing DISPLAY files under Windows (or under WINE).

In addition, the following special codes are interpreted:

Clear the screen and home the cursor

<FF> <FF> = <Ctrl-L> = ASCII 12

Note that the screen is filled with the current display color.

Specify background and foreground colors

<SI><bg><fg> <SI> = <Ctrl-O> = ASCII 15

Set the display colors to the specified background and foreground colors, where <bg> and <fg> are the 2 hex digits representing 1 byte, corresponding to the standard PC display attributes:

0 = black 8 = dark grey 1 = dark blue 9 = bright blue 2 = dark green a = bright green 3 = dark cyan b = bright cyan 4 = dark red c = bright red 5 = dark purple d = bright purple 6 = brown e = yellow 7 = light grey f = white

Picking a bright color (8-f) for the background, results in the corresponding dark color (0-7), with the foreground flashing.

Colors are not visible over the serial console.

See also Examples/message file.

Display graphic from filename

<CAN>filename<newline> <CAN> = <Ctrl-X> = ASCII 24

If a VGA display is present, enter graphics mode and display the graphic included in the specified file. The file format is an ad hoc format called LSS16. The included Perl program, "ppmtolss16", can be used to produce these images. This Perl program also includes the file format specification.

The image is displayed in 640x480, 16-color mode. Once in graphics mode, the display attributes (set by <SI> code sequences) work slightly differently: the background color is ignored, and the foreground colors are the 16 colors specified in the image file. For that reason, ppmtolss16 allows you to specify that certain colors should be assigned to specific color indices.

Color indices 0 and 7 in particular, should be chosen with care: 0 is the background color, and 7 is the color used for the text printed by Syslinux itself.

See also info about mtPaint to help with LSS16 background images.

Return to text mode

<EM> <EM> = <Ctrl-Y> = ASCII 25

If we are currently in graphics mode, return to text mode.

Output printing modes

<DLE>..<ETB> <Ctrl-P>..<Ctrl-W> = ASCII 16-23

These codes can be used to select in which modes to print a certain part of the message file. Each of these control characters selects a specific set of modes (text screen, graphics screen, serial port) for which the output is actually displayed:

Character Text Graph Serial ------------------------------------------------------ <DLE> = <Ctrl-P> = ASCII 16 No No No <DC1> = <Ctrl-Q> = ASCII 17 Yes No No <DC2> = <Ctrl-R> = ASCII 18 No Yes No <DC3> = <Ctrl-S> = ASCII 19 Yes Yes No <DC4> = <Ctrl-T> = ASCII 20 No No Yes <NAK> = <Ctrl-U> = ASCII 21 Yes No Yes <SYN> = <Ctrl-V> = ASCII 22 No Yes Yes <ETB> = <Ctrl-W> = ASCII 23 Yes Yes Yes

For example, the following will actually print out which mode the console is in:

<DC1>Text mode<DC2>Graphics mode<DC4>Serial port<ETB>

End of file

<SUB> <SUB> = <Ctrl-Z> = ASCII 26

End of file (DOS convention).

Beep

<BEL> <BEL> = <Ctrl-G> = ASCII 7

Beep the speaker.

See also

• mtPaint can create/edit/convert/save lss16 graphic files to be used as background images in DISPLAY help message boot screens. Hint: use (or convert to) "Indexed" 16 colors palette, then save as .lss.
  
• IsoLinux Mate can help with writing DISPLAY files under Windows (or under WINE).