the cutting room mirror

Zaxxan

Most. Obvious. Zaxxon clone. Ever.

Source Code Fragment#

Beginning at 68B2 in the .tap dump, there's a piece of code lying in it.

                ,E 
        INC HL
        LD  (HL),D
        DEC H
        POP BC
        LD  DE,(#DA06)
        LD  A,141
        LD  (DE),A
        JP  STOR
REVERS  LD  A,B
        CP      L
        LD  B,A
        LD  A,C
        CP      L
        INC A
        LD  C,A
        EX  DE,HL
        ADD HL,BC
        EX  DE,HL
        LD  (HL),B
        DEC HL
        LD  (HL),C
        JR  POK
TST PUSH    HL
        PUSH    DE
        EX  DE,HL
        LD  DE,-240
CHCO    LD  A,H
        CP  #D0
        JP  M,RETU
        JR  NZ,NICH
        LD  A,L
        CP  10
        JP  P,NICH
        CP  0
        JP  M,NICH
        LD  A,255
        JR  POP
NICH    ADD HL,DE
        JR  CHCO
RETU    LD  A,0
POP POP DE
        POP HL
        RET
TSM LD  HL,#DC00
        LD  B,64
SLP CALL    LOAD
        LD  A,D
        CP  0
        JR  Z,SCD
        PUSH    HL
        EX  DE,HL
        LD  DE,-10
        ADD HL,DE
        LD  (HL),0
        EX  DE,HL
        POP HL
        CALL    TST
        CP  255
        JR  Z,DS
        PUSH    HL
        EX  DE,HL
        LD  DE,-10
        ADD HL,DE
        EX  DE,HL
        POP HL
        LD  A,(DE)
        CP  0
        JR  NZ,DS
        CALL    TST
        CP  255
        JR  Z,DS
        LD  A,139
        LD  (DE),A
SSTO    LD  (HL),D
        DEC HL
        LD  (HL),E
        INC HL
SCD INC HL
        DJNZ    SLP
        RET
DS  LD  DE,0
        JR  SSTO
CHECK   PUSH    HL
        LD  HL,(#DA02)
        LD  A,(HL)
        CP  0
        JP  Z,PARE
        CP  133
        JP  Z,PARE
        CP  10
        JP  Z,THVOR
YLF LD  HL,(#DA02)
        LD  (HL),135
        CALL    PRINT
        LD  E,0
        LD  D,8
L91 LD  HL,#5800
        LD  BC,768
L90 LD  A,(HL)
        AND 199
        ADD A,E
        LD  (HL),A
        INC HL
        DEC BC
        LD  A,B
        OR  C
        JR  NZ,L90
        LD  A,E
        ADD A,8
        LD  E,A
        LD  C,100
        SLA A
        ADD A,12

References#


  1. HomeComputerWeekly-041, p. 36-37↩︎
  2. Popular Computing Weekly (1983-11-24), p. 76↩︎