30534: Place stack return address into character's buffer
This routine is used by several others to place the address of the instruction following
"CALL 30534" into the character's buffer (so that it takes over control of the character
from that point)
H
Character number
30534
C1
POP BC
Get the return address in BC
30535
2E11
LD L,17
Place it in bytes 17 and 18 of the character's buffer