/* WIZ registers */
    #define WIZ_MODE 0x27
    #define WIZ_ADR0 0x2F
    #define WIZ_ADR1 0x37
    #define WIZ_DATA 0x3F

    /* WIZ modes */
    #define WIZ_MODE_STD 1  // indirect addressing
    #define WIZ_MODE_INC 3  // indirect addressing, auto increment

    unsigned char wiz_r(unsigned int adr)
    {
      #asm
      pop de ; caller address
      pop hl ; address to be read
      push hl; restore stack
      push de

      ld a,WIZ_MODE_STD    ; set indirect address mode
      out (WIZ_MODE),a

      ld a,l               ; set read address
      out (WIZ_ADR1),a
      ld a,h
      out (WIZ_ADR0),a

      in a,(WIZ_DATA)      ; read value
      ld h,0               ; return value in HL
      ld l,a
      #endasm
    }

    void wiz_s(unsigned int adr, unsigned char data)
    {
      #asm
      pop de ; caller address
      pop bc ; data
      pop hl ; address to be written
      push hl; restore stack
      push bc
      push de

      ld a,WIZ_MODE_STD    ; set indirect address mode
      out (WIZ_MODE),a

      ld a,l               ; set write address
      out (WIZ_ADR1),a
      ld a,h
      out (WIZ_ADR0),a

      ld a,c               ; write data
      out (WIZ_DATA),a
      #endasm
    }