ORG 256
        JP CONT
        JP KEY
        JP ALLKEY
        JP JOY
        JP BEEP
KEY     EX (SP),HL
        LD A,(HL)
        INC HL
        EX (SP),HL
        OUT (0B5H),A
        IN A,(0B5H)
        RET
ALLKEY  PUSH BC
        LD BC,0AFFH
A1      LD A,B
        DEC A
        OUT (0B5H),A
        IN A,(0B5H)
        AND C
        LD C,A
        DJNZ A1
        POP BC
        RET
JOY     PUSH BC
        LD B,0
        CALL JOY1
        LD A,C
        LD (JOY2+1),A
        CALL JOY1
        LD A,C
JOY2    OR 0
        POP BC
        RET
JOY1    LD C,8
JOY3    LD A,B
        INC B
        OUT (0B5H),A
        IN A,(0B6H)
        RRA
        CCF
        RL C
        JR NC,JOY3
        RET
BEEP    LD A,L
        SRL L
        SRL L
        CPL
        AND 3
        LD C,A
        LD B,0
        LD IX,L03D1
        ADD IX,BC
        LD A,(L5C48)
        AND 38H
        RRCA
        RRCA
        RRCA
        OR 0
L03D1   NOP
        NOP
        NOP
        INC B
        INC C
L03D6   DEC C
        JR NZ,L03D6
        LD C,63
        DEC B
        JP NZ,L03D6
        XOR 18H
        OUT (0A7H),A
        LD B,H
        LD C,A
        BIT 4,A
        JR NZ,L03F2
        LD A,D
        OR E
        JR Z,L03F6
        LD A,C
        LD C,L
        DEC DE
        JP (IX)
L03F2   LD C,L
        INC C
        JP (IX)
L03F6   EI
        RET
L5C48   EQU 5C48H
CONT    LD SP,STACK
        LD B,1
        LD C,28
        LD D,0
        EXOS 16
        LD C,0FAH
        EXOS 25
        LD A,0FAH
        OUT (0B2H),A
        LD C,0FCH
        EXOS 25
        LD A,0FCH
        OUT (0B1H),A
        LD A,192
        LD DE,4000H
        EXX
        LD DE,4000H
        LD HL,4004H
        LD BC,13
L1      EX AF,AF'
        EXX
        LD HL,LINE
        LD BC,16
        LDIR
        EXX
        LD (HL),E
        INC HL
        LD A,D
        RRA
        RRA
        RRA
        AND 3
        OR 58H
        LD (HL),A
        INC HL
        LD (HL),E
        INC HL
        LD (HL),D
        ADD HL,BC
        INC D
        LD A,D
        AND 7
        JR NZ,L2
        LD A,E
        ADD A,32
        LD E,A
        CCF
        SBC A,A
        AND 0F8H
        ADD A,D
        LD D,A
L2      EX AF,AF'
        DEC A
        JR NZ,L1
        EXX
        LD HL,SYNC
        LD BC,HOSSZ
        LDIR
        XOR A
        OUT (82H),A
        LD A,192
        OUT (83H),A
        LD C,0FDH
        EXOS 25
        LD C,0FBH
        EXOS 25
        LD A,0FBH
        OUT (0B3H),A
        LD A,0FDH
        OUT (0B1H),A
        LD DE,SCREEN
        LD A,1
        EXOS 1
        LD DE,4000H
        LD BC,1B00H
        LD A,1
        EXOS 6
        LD A,1
        EXOS 3
        LD A,1 
        LD DE,ALSO
        EXOS 1
        LD DE,7776H
        LD BC,38A4H
        LD A,1
        EXOS 6
        LD A,1
        EXOS 3
        LD A,1
        LD DE,FELSO
        EXOS 1
        LD DE,0E8C4H
        LD BC,173CH
        LD A,1
        EXOS 6
        LD A,1
        EXOS 3
        LD A,48
        OUT (0B4H),A
        LD A,195
        LD HL,ENABLE
        LD (7777H),A
        LD (7778H),HL
        LD HL,ISR
        LD (38H),A
        LD (39H),HL
        LD HL,JOY
        LD (28H),A
        LD (29H),HL
        LD A,20H
        OUT (0A8H),A
        OUT (0ACH),A
        XOR A
        OUT (0B1H),A
        LD HL,4000H
        LD DE,STACK
        LD BC,4000H-STACK
        LDIR
        LD A,0FDH
        OUT (0B1H),A
        JP 77B2H
ISR     PUSH AF
        LD A,30H
        OUT (0B4H),A
        POP AF
        EI
        RET
ENABLE  PUSH AF
        LD A,30H
        OUT (0B4H),A
        POP AF
        JP 0EE00H
SCREEN  DEFB ALSO-$-1
        DEFM "CRESTA.SCR"
ALSO    DEFB FELSO-$-1
        DEFM "ALSO"
FELSO   DEFB LINE-$-1
        DEFM "FELSO"
LINE    DEFB 255,14H,15,2FH,0,0,0,0
        DEFB 0,32,72,104,144,176,216,248
SYNC    DEFB 0F5H,02H,0,0,0,0,0,0
        DEFB 0,0,0,0,0,0,0,0
        DEFB 247,8,11,73H,0B8H,0FEH,0E9H,1
        DEFB 0,216,216,0,0,0,0,0
        DEFB 217,12H,63,0,0,0,0,0
        DEFB 0,0,0,0,0,0,0,0
        DEFB 253,16,63,0,0,0,0,0
        DEFB 0,0,0,0,0,0,0,0
        DEFB 252,16,6,63,0,0,0,0
        DEFB 0,0,0,0,0,0,0,0
        DEFB 255,90H,63,32,0,0,0,0
        DEFB 0,0,0,0,0,0,0,0
        DEFB 252,12H,6,63,0,0,0,0
        DEFB 0,0,0,0,0,0,0,0
        DEFB 207,13H,63,0,0,0,0,0
        DEFB 0,0,0,0,0,0,0,0 
HOSSZ   EQU $-SYNC
STACK   EQU+200