| Routines

7EF1: Make BOY WANDER write on a blackboard

Used by BOY WANDER's command lists 0x20, 0x2E, 0x32, 0x36 and 0x38. Makes BOY WANDER write on the blackboard he's standing next to unless a certain event has already happened or the board is dirty.
Input
H | 0xCE (BOY WANDER)
7EF1 | CALL $627D | Collect the event identifier parameter from the command list
7EF4 | CALL $7C8F | Check whether the event (the arrival of a teacher or the end of the lesson) has happened
7EF7 | LD BC,$6880 | Redirect control to the routine at 6880 (write on board) if the event has not happened, then return to 7EFD (below)
7EFA | CALL Z,$639F
7EFD | JP $638C | Move to the next command in the command list