This module extends the VDU23,17,5 sequence with a flags parameter. In addition to the default behaviour of swapping the text colours, this allows both the text and graphics colours to be swapped independently.

VDU23,17,5,flags,0,0,0,0,0,0

Where flags is defined to be:

b0	swap the text colours
b1	swap the graphics colours

b2-b7	reserved

If both b0 and b1 are clear, the default behaviour of swapping only the text colours applies. Otherwise you can choose what to swap.

The zip contains a little demo program and no other documentation.