Although the PCW is a monochrome machine, it nevertheless internally maintains settings for foreground and background colour. That's why the ESC b and ESC c escape codes are still there and still take 6-bit colour values.
What I hadn't realised until today was that there's a little difference of opinion between the two modules in the EMS file responsible for screen handling. SCR, the low-level module responsible for actually drawing characters on the screen, has default colour settings of Border=1, Background=1, Foreground=60 -- that is, bright yellow on dark blue, like the CPC at startup.
cpm_yellow.png
At a slightly higher level is TE, the Terminal Emulator, responsible for interpreting escape codes, setting the cursor position and so on. It initialises after SCR, and decides to set the colours to Background=1, Foreground=63 -- bright white on dark blue.
cpm_white.png
So far, I haven't found anything similar in LocoScript. LocoLink 2.02 incorporates SCR but not TE, so it sticks with the yellow on blue colour scheme.
ha that's neat! If only we had colour plane support in the PCW ASIC. :0 Or an expansion card that hijacked the video so we could implement an 80x32 text expansion with greyscale. :)
-a