Prints one character in the story window, which fills the upper part of the screen and uses the game's own 6-pixel font (77BC). The screen address is kept at $768F, the pixel offset within the byte at $7691, and the number of characters left on the line at 768E (42 per line).

Letters are converted to lower case, except that the first letter after a full stop or a new line is capitalised: the flag at $B5F5 is set by those, and cleared once a capital has been printed. This is why the game's text needs no capital letters in the dictionary.

A carriage return sends the finished line to the ZX Printer if it is switched on (7B15), then scrolls the story window up (775E) and starts a new line. Before scrolling, the game checks the line counter at B606, which is set to 9 each time the player enters a command: after that many lines, each further line waits (for about half a second, or until a key is pressed) so that long bursts of text do not rush past unread. A key held down at that point has to be released before the text continues.

A backspace moves back 6 pixels (7754) and rubs out the character there. A full line wraps automatically.

If $7692 is non-zero, that many spaces are printed at the start of the line first (an indent). This is the routine I used as a hook in the emulator to capture everything the game printed.