Examples Of Forming Basic Playfields - Commodore Amiga Hardware Reference Manual

5. Define Modulo. Set registers BPLIMOD and BPL2MOD. Set modulo to 0 for
non-interlaced, 40 for interlaced.
6. Write Copper Instructions To Handle Redisplay.
7. Enable Color Display. Set bit 9 in BPLCONO to enable the color display on a
composite video monitor. RGB video is not affected.
EXAMPLES OF FORMING BASIC PLAYFIELDS
The following examples show how to set the registers and write the coprocessor lists for
two different play fields.
The first example sets up a 320 x 200 playfield with one bit-plane, which is located at
$21000. Also, a Copper list is set up at $20000.
CUSTOM
BPLCONO
BPLCONI
BPLCON2
BPLIMOD
DDFSTRT
DDFSTOP
DIWSTRT
DIWSTOP
VPOSR
COLOROO
COLOROI
COLOR02
COLOR03
DMACON
COPILCH
LEA
MOVE.W
MOVE.W
MOVE.W
MOVE.W
MOVE.W
MOVE.W
MOVE.W
MOVE.W
MOVE.W
EQU $DFFOOO
EQU $100
EQU $102
EQU $104
EQU $108
EQU $092
EQU $094
EQU $08E
EQU $090
EQU $004
EQU $180
EQU $182
EQU $184
EQU $186
EQU $096
EQU $080
CUSTOM,AO
#$1200,BPLCONO(AO)
#O,BPLCONl(AO)
#O,BPLIMOD(AO)
#$0038,DDFSTRT(AO)
#$OODO,DDFSTOP(AO)
#$2C81,DIWSTRT(AO)
#$F4Cl,DIWSTOP(AO)
#$OFOO, COLOROO(AO)
#$OFFO,COLOROl(AO)
; Copper location register 1
; (high three bits)
;AO points at custom chips
; One bit-plane, enable composite color
;Set horizontal scroll value to 0
;Set modulo to 0 for all odd btt-planes
;Set data-fetch start to $38
;Set data-fetch stop to $DO
;Set DIWSTRT to $2C81
;Set DIWSTOP to $F4C1
;Set background color to red
;Set color register 1 to yellow
Playfield Hardware 55