INT 15 - TopView - SEND MESSAGE - "ADDTO" - WRITE CHARS AND ATTRIBS TO WINDOW
AH = 12h
BH = 0Ah
BL = window to write to
00h window handle is DWORD on top of stack
01h current task's default window
0Ch (DV 2.26+) default window of task owning handle on top of stack
0Dh (DV 2.26+) default window of parent of current task
STACK:  DWORD count of attributes
DWORD address of attribute string
DWORD count of characters
DWORD address of character string
Notes:  if one string is longer than the other, the shorter one will be reused
until the longer one is exhausted
the cursor is left just after the last character written

See also: 1512

1512 - TopView - SEND MESSAGE - "ADDTO" - WRITE CHARS AND ATTRIBS TO WINDOW