git.defcon.no Git - z80cpm/blob - soundtest1.asm

   1 ; soundtest1.asm
   2 ; Requires an AY-3-891x or YM2149, with address decoding making
   3 ; a write/read to $50 a data write/read, a write to $51 an address write,
   4 ; and any other combination being an AY Idle condition.
   5 ; Supernaive bruteforce approach, with random delay values.
   6 ; Produces a frequency sweep by counting down 0..255
   7
   8 CPU Z80
   9 OUTPUT HEX
  10
  11 * = $100
  12 START           LD A, 7
  13                 OUT     ($51), A
  14                 LD A, $FF
  15                 OUT     ($50), A
  16
  17                 LD A, 8
  18                 OUT     ($51), A
  19                 LD A, 9
  20                 OUT     ($50), A
  21
  22                 LD A, 9
  23                 OUT     ($51), A
  24                 LD A, 0
  25                 OUT     ($50), A
  26
  27                 LD A, $A
  28                 OUT     ($51), A
  29                 LD A, 0
  30                 OUT     ($50), A
  31
  32                 LD A, 7
  33                 OUT     ($51), A
  34                 LD A, $FE
  35                 OUT     ($50), A
  36
  37                 LD A, 1
  38                 OUT     ($51), A
  39                 LD A, 1
  40                 OUT     ($50), A
  41
  42                 LD A, 0
  43                 OUT     ($51), A
  44
  45                 LD A, $FF
  46 LOOP1           OUT     ($50), A
  47                 PUSH AF
  48                 LD A, 8
  49                 CALL DELAY
  50                 POP AF
  51                 DEC A
  52                 JR NZ, LOOP1
  53
  54                 LD A, 7
  55                 OUT     ($51), A
  56                 LD A, $FF
  57                 OUT     ($50), A
  58
  59                 RET
  60
  61 ; End of main code.
  62
  63 ;Start of delay routine..
  64 DELAY           PUSH BC
  65 DLY_START       LD C, 10
  66 DLY_LOOPO       LD B, 0
  67 DLY_LOOPI       DJNZ DLY_LOOPI
  68                 DEC C
  69                 JR NZ, DLY_LOOPO
  70                 DEC A
  71                 JR NZ, DLY_START
  72                 POP BC
  73                 RET