Tandy 1000 SL Technical Reference Manual page 540

BIOS Services
Write String
Display a string of characters on screen.
Entry Conditions
AH
=
13H
ES:BP
=
pointer to start of string
CX
DX
BH
BL
AL
=
length of string (attributes do not count)
=
startingcursorposition (DH
=
row, DL
=
column)
=
page number (for text modes)
=
attribute for characters (graphics modes)
=
00: Characters only string, cursor not updated
=
01: Characters only string, cursor updated
=
02: Character, attribute alternating string, cursor
=
03: Character, attribute alternating string, cursor
not updated
updated
19.