- <Ctrl+X> - Sets white text on a black background.
- <Esc>, "L" - Reads the character under the cursor and stores the ASCII code in (WKAREA) (0xFE1A). This is equivalent to SPK$ except for how it returns the result. What is interesting is that it will work even for the graphics screen, where the VDP does not have the ASCII code. In this case it works by matching the bit pattern at the cursor against the text pattern table.
- <Esc>, "R", cc - Where cc = 16 * paper + ink. Sets the printing colours as specified and clears the printing attributes.
- <Esc>, "U", 0xFF - Resets virtual screens 0, 1, 4, 5 & 7 to their default states. Reloads the text pattern table. Selects VS 4 (Graphics screen) and clears the screen.
- <Esc>, "V", 0xFF - Resets virtual screens 0, 1, 5 & 7 (text screens) to their default states for Basic. Leaves virtual screen 5 selected.
- <Esc>, "W", 0xFF - Resets virtual screens 0, 1, 5 & 7 (text screens) to their states for PANEL. Leaves virtual screen 5 selected.
I expect that the ROM makes use of most of these elsewhere in the code, but <Ctrl+X> is a strange one.