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Text File  |  1996-12-24  |  982b  |  32 lines
  1. *************************
  2. *  USR2 Source Code     *
  3. *  MindCraft Assembler  *
  4. *  By Mark R. Craven    *
  5. *  Copyright (c) 1990   *
  6. *  MindCraft Publ. Co.  *
  7. *  Concord, MA 01742    *
  8. *************************
  9.  
  10.                    ORG        $300
  11.  
  12. FP_TO_INT EQU        $E10C
  13. INT_TO_FP EQU        $E2F2
  14. NUM_STORE EQU        $00A1
  15. SPEAKER     EQU        $C030
  16. TMP_STORE EQU        $0008
  17.  
  18.                    JSR        FP_TO_INT
  19.                    LDY        NUM_STORE
  20.                    STY        TMP_STORE     ;Temporarily Store
  21.                    JSR        INT_TO_FP
  22. PITCH         LDX        #$10          ;Tone Pitch
  23. TOGGLE       LDA        SPEAKER       ;Toggle Speaker
  24.                    LDA        TMP_STORE     ;Retrieve Tone Length
  25. PAUSE         DEY
  26.                    BNE        PAUSE   
  27.                    DEX
  28.                    BNE        TOGGLE  
  29.                    DEC        TMP_STORE     ;Decrement Tone Length
  30.                    BNE        PITCH
  31.                    RTS
  32.