| Routines

63B5: Set the interruptible subcommand (unused)

This routine is not used. It drops the return address from the stack and copies it into bytes 0x09 and 0x0A of the character's buffer (thus setting the interruptible subcommand), and then jumps to the routine whose address is in BC.
Input
BC | Routine address
H | Character number (0xB7-0xD6)
63B5 | LD A,H | A=character number
63B6 | POP HL | Drop the return address from the stack into HL
63B7 | PUSH BC | Push the routine address in BC onto the stack
63B8 | LD C,L |
63B9 | LD L,$09 |
63BB | JR $63AA | Copy the return address into bytes 0x09 and 0x0A of the character's buffer, and jump to the routine whose address was in BC on entering this routine