Commodore Amiga A500 Technical Reference Manual page 208

1
LINE D
W
1
LINE MODE (line draw)
BIT# BLTCONO BLTCON l
1 5 START3 0
14 START2 0
1 3 START 1 0
1 2 START0 0
11 1 0
1 0 0 0
09 1 0
08 1 0
07 LF7 0
0 6 LF6 SIGN
0 5 LF5 OVF
0 4 LF4 SUD
0 3 LF3 SUL
0 2 LF2
AUL
0 1 LF1 SING
0 0 LFO LINE(= 1)
START3-0 Starting point of line (0 thru 1 5 hex)
LF7-0
Logic function minterm select lines
should be preloaded with
4A
in order
to select the equation D
=
(AC
+
ABC).
Since A contains a single bit true
(8000), most bits will pass the C field
unchanged (not
A
and C), but one bit
will invert the C Field and combine it
with texture (A and B and not C). The
A bit is automatically moved across
the word by the hardware.
LINE
Line mode control bit (set to 1)
SIGN Sign flag
OVF Word overflow flag
SING
Single bit per horiz. line
for use with subsequent Area Fill
SUD Sometimes Up or Down
(
=
AUD*)
SUL Sometimes Up or Left
AUL
Always Up or Left
The 3 bits above select the Octant for line draw:
OCT SUD SUL AUL
-
0
1 1
0
1 0 0 1
2 0 1 1
3
1
1 1
4 1 0 1
5 0 1
0
6 0 0 0
7
0
0 0
Blitter start and size (Window, width height)