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Durango colour palette

The Durango-X and Durango-S colour computers have a colour display mode with 128 x 128 pixels. Using 4 bits per pixel, it allows the simultaneous use of 16 colours on the screen. Unlike some old computers like the ZX-Spectrum, Commodore 64, MSX etc there are no restrictions about how many different colours may appear in a certain area.

Palette colour list

Decimal Hex Binary Name HTML equivalent
0 $0 %0000 Black #000000
1 $1 %0001 Green #00AA00
2 $2 %0010 Red #FF0000
3 $3 %0011 Orange #FFAA00
4 $4 %0100 Pharmacy green #005500
5 $5 %0101 Lime #00FF00
6 $6 %0110 Mystic Red #FF5500
7 $7 %0111 Yellow #FFFF00
8 $8 %1000 Blue #0000FF
9 $9 %1001 Deep Sky Blue #00AAFF
10 $A %1010 Magenta #FF00FF
11 $B %1011 Lavender Rose #FFAAFF
12 $C %1100 Navy Blue #0055FF
13 $D %1101 Cyan #00FFFF
14 $E %1110 Pink Flamingo #FF55FF
15 $F %1111 White #FFFFFF

This palette is designed in a way that changing the Least Significant Bit will produce a noticeable luminance change, thus providing adequate contrast.


Depending on your display and component tolerances, some colours may differ in practice -- dark green in particular will usually look darker, thus minimising the difference between colours where this bit changes.

Palette file

You may download a GIMP palette file with the colours available on Durango-X for convenient artwork creation.

Display format

In all video modes, Durango-X uses a linear framebuffer. Its dimensions being powers of 2, any screen position is easily computed into the corresponding memory address.

Colour mode

Display memory follows the "chunky" model -- all bits defining a pixel are packed together into the same byte. At 4 bpp, two pixels are encoded on every byte:

128 64 32 16 8 4 2 1
left B left g left R left G right B right g right R right G

where R=red, B=blue, G=high green (67%) and g=low green (33%)

Greyscale mode

Whenever the colour mode is active, the four bits for each pixel are sent to the video mixer thru a crude Digital-to-Analog Converter (DAC). This mode can be displayed on a SCART-equipped TV by setting the FAST BLANKING pin low, which is done thru software by setting low bit D3 in the video mode register ($DF80).


This control bit is write only, thus the current mode cannot be checked. Software is expected to keep this bit set all the time, as will be ignored in HIRES mode anyway.

The bits on every byte are now interpreted as follows:

128 64 32 16 8 4 2 1
L0 L1 L2 L3 R0 R1 R2 R3

Note the reverse bit order, intended to closely (but not exactly) match the luminance values of the colours.


This mode was intended as an emergency resource for SCART-equipped devices that do not support RGB input (e.g. VCRs) and won't be available in most configurations, like the Sync-on-Green or PAL composite option.

RGB to Component video Converter

For improved compatibility with modern TV sets, this option will be included in Revision 2 of the Durango-X board; however, a standalone converter is also available and suitable for SCART-equipped v1 Durangos.

The Component Video input expects three signals (besides Audio):

  • Pr (Red difference)
  • Pb (Blue difference)
  • Y (Luminance)

The two first signals are generated inside the converter, and the last one is taken straight from the composite video output of Durango-X. But this signal is not really Luminance, but a greyscale signal instead -- close, but not a perfect match. For better colour accuracy when using the Component Video converter, the following changes are suggested in the Durango-X simple DAC:

Designator Value for greyscale Value for Luminance
R107 5K6 8K2
R109 22K 18K
R110 39K 33K


This improved colour accuracy comes with the cost of impairing greyscale linearity but, as mentioned, this is rarely an issue.


Since the aforementioned mod has no effect whatsoever on the RGB output, it is highly recommended to build every Durango-X v1 DAC this way, just in case the Component Video converter is ever used.