Atari ST series Technical Reference Manual page 171

*** And wait for mouse button release
wait:
move.w M0USE_BT(a5),d3
btst #l,d3
bne wait
*** end program
move.l #0,-(sp)
trap #1
*** Data for input is stored here
.data
*** mouse pointer data
dc. w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
dc.w
*** storage for old mouse data and sprite save area
.bss
psave:
ds.w
ssave: ds.w
savebuf: ds.w
.end
If you position the mouse pointer over the sprite while
it's moving, a bit of residue will be left on the screen. That's
because part of the pointer is saved to the sprite's save block,
and restored when the sprite moves on. To avoid this prob­
lem, try hiding the mouse pointer before undrawing the
sprite, and showing it again after drawing the sprite.
Text
Since text characters on the ST are really drawn on the
graphic screen, dot by dot, text rendering turns out to be an­
other special case of bit blitting. The function used to copy a
single text character to the screen is called TextBlt ($A008).
Because there are many variations on text printing on the ST,
TextBlt uses a lot of input variables. The primary line A vari­
ables that influence text printing are shown in Table 7-11.
Line A Routines
* GEMDOS terminate command
* call GEMDOS and exit
0 , 2
8 8 1
, , ,
$OFFO, $0FF0, $0FF0, $FFFE
$FFFE, $FFFE, $FEFE, $FC7E
$FEFE, $FFFE, $FFFE, $FFFE
$OFFO, $0FF0, $0FF0,
0 0 0 0 0 0 0 0
$ , $ , $0380, $0380
$0380, $3FF8, $3EF8, $3C78
$3EF8, $3FF8, $0380, $0380
0 0 0 0 0 0 0 0
$0380, $ , $
37
37
133 * enough for 4 bit planes
$0000
$0000
,
163