This is The Hobbit's line editor. It starts by setting the idle timer at $B604 to 3000 (see 7240), and setting $B5F2 and $B5EB to 1, then prints the '>' prompt and a space.

Characters are collected into the input buffer at 6FF0. B counts the space left, starting at 128 ($80), so bit 7 of B being set means that nothing has been typed yet. C is 0 until the first key has been handled.

Keys are fetched by 7240, which also types WAIT for the player if they are idle for too long. Each key is then handled as follows:

• '@' ($40, SYMBOL SHIFT + 2) as the very first key: repeat the last command (6E71).
• Any key that is the first key of the line: 6E46 checks for the cursor keys, which produce a one-letter movement command on their own.
• $18 (SYMBOL SHIFT + 0): delete the whole line (6E82).
• $08 (CAPS SHIFT + 0 or 5, or 5 on its own): delete the last character, by printing a backspace, putting B back up by one and moving HL back, unless the line is empty.
• Letters (codes $40 and above), space, double quote, full stop, comma and ENTER are accepted. Everything else is ignored.

An accepted character is stored in $B5F5 (the printer uses this to remember the last punctuation mark), echoed to the screen via 7580, and put in the buffer, as long as there is room (B not 0). ENTER ($0D) ends the line: it is stored like any other character, and the routine returns with the Z flag reset.

Note that letters are not converted to upper case here. They do not need to be: the tokeniser keeps only the low five bits of each letter (6F3E), and that is the same for 'a' and 'A'.