VDU 19

Define Logical Colour.

VDU 19

Syntax	VDU 19,<logical>,<physical>,<red>,<green>,<blue>
Character stream (hex)	13 <logical> <physical> <red> <green> <blue>
Description	Set the logical colour <logical> to be the physical colour <physical>.

Description

VDU 19, sets the logical colour, used in a GCOL (VDU 18) or a COLOUR (VDU 17) to the provided physical colour. On the 8-bit machines, the physical colour list is the same as the default for a 16 colour mode, as shown below, and the red, green and blue parameters are given as zero. On 32-bit systems and compatible extensions for 8-bit systems, the individual red/green/blue colour levels can be set with the last three parameters.

Default physical colours

Logical colour	Physical colour
0	Black
1	Red
2	Green
3	Yellow
4	Blue
5	Magenta
6	Cyan
7	White
8	Flashing black/white
9	Flashing red/cyan
10	Flashing green/magenta
11	Flashing yellow/blue
12	Flashing blue/yellow
13	Flashing magenta/green
14	Flashing cyan/red
15	Flashing white/black

The logical colour value is MODed by the number of colours in the mode, so in a four colour mode, defining colour 4 will alter colour 0.

On a BBC Micro, this VDU call performs similar to OSBYTE &9B and will update the ULA colour registers. It will automatically invert the physical colour value as required by the ULA.

Calling from BBC BASIC

On BASIC V and later:

• COLOUR l,p sends VDU 19,l,p,0,0,0
• COLOUR l,r,g,b sends VDU 19,l,16,r,g,b

--Tautology 13:10, 1 May 2011 (UTC)