Colours

INK n, PAPER n and BORDER n take any value from 0 to 255. The compiler already checks all three against that full range - they are declared as a generic value parameter, not a colour-specific one - so nothing needed to change there; only what the interpreter does with the upper part of the range is new.

Row 0 is the classic block, 0-15. Every row after it is the extended range, 16-255, left to right in numeric order - read a cell's number straight into INK, PAPER or BORDER.

0 to 15 are the classic Spectrum colours, unchanged: 0 to 7 are the eight ULA colours in the usual INK/PAPER order, and 8 to 15 are the same eight again, bright.

16 to 255 are the standard Next colour of that same number - the RRRGGGBB byte convention already used for location art and Gfx2Next: bits 7-5 are red, bits 4-2 are green, and bits 1-0 are blue. It is one mental model for pictures and text alike - whatever a number means to Gfx2Next, it means the same thing here.

There is no palette file to supply, and none is needed. Every one of the 256 standard Next colours is already addressable by its own number, so INK, PAPER and BORDER simply reach further into the same fixed palette location art draws from - there is nothing to load, generate or ship alongside your database.

For any n from 16 to 255:

red   = (n >> 5) & 7      -- 0-7
green = (n >> 2) & 7      -- 0-7
blue  =  n       & 3      -- 0-3

or build a number from the three components the other way round:

n = red*32 + green*4 + blue

A few worked examples: 224 is full red (7,0,0), 28 is full green (0,7,0), and 255 is white (7,7,3, the maximum of everything). 3 works out to pure blue by the same arithmetic, but 3 is inside 0 to 15, so it reads as the classic colour it already was rather than as blue - every value below 16 keeps its classic meaning regardless of what the RRRGGGBB arithmetic would say about that same byte; only 16 and above are decoded this way.

Because blue only has two bits, the same thing is true of every pure blue: with red and green both 0, the value never climbs past 3, so a saturated blue with no red or green in it is always a classic colour (1, or 9 for bright), never one from the extended range. Add a touch of red or green and the value moves above 15, with a matching shift in the resulting hue.

If you would rather see the numbers than compute them, the colour chart above is exactly this palette, indexed. Any paint or sprite tool that lets you pick from the Next's standard RGB332 palette - the same one described under Custom mouse pointer - previews colour n at index n too, since it is the identical 256-colour palette INK, PAPER and BORDER draw from.

One value is reserved: PAPER 227 makes the paper transparent rather than magenta, because 227 is #FF00FF, the transparent colour throughout NextDAAD; INK 227 likewise makes the glyph shapes transparent; BORDER 227 is unaffected and renders magenta; and any other colour that would land on the transparent value is shifted one step up the green scale, which is why colour 11 renders as a very slightly different magenta.