o High resolution:
*
640
pixels
in
each horizontal line.
* Set bit
15
in
register
BPLCONO
(HIRES).
e. Specify interlaced or non-interlaced mode:
o Interlaced mode:
* 400 vertical lines.
* Set bit 2
in
register
BPLCONO
(LACE).
o Non-interlaced mode:
* 200 vertical lines.
* Clear bit 2 in
BPLCONO
(LACE).
2.
Allocate
Memory.
To
calculate data-bytes
in
the total bit-planes, use the
follow-
ing formula:
Bytes per line * lines
in
playfield * number of bit-planes
3.
Define
Size
of
Display
Window.
o Write
start
position of display window
in
DIWSTRT:
* Horizontal position in bits 0 through 7 (low-order bits).
* Vertical position
in
bits 8 through
15
(high-order bits).
o Write stop position of display window in DIWSTOP:
* Horizontal position in bits 0 through
7.
* Vertical position
in
bits 8 through
15.
4.
Define
Data
Fetch.
Set registers DDFSTRT and DDFSTOP:
o For DDFSTRT, use the horizontal position as shown
in
"Setting the Display
Window Starting Position."
o For DDFSTOP,
use
the horizontal position as shown
in
"Setting the Display
Window Stopping Position."
54 Playfield Hardware
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