; soundtest1.asm
; Requires an AY-3-891x or YM2149, with address decoding making
; a write/read to $50 a data write/read, a write to $51 an address write,
; and any other combination being an AY Idle condition.
; Supernaive bruteforce approach, with random delay values.
; Produces a frequency sweep by counting down 0..255

CPU Z80
OUTPUT HEX

* = $100
START 		LD A, 7
		OUT	($51), A
		LD A, $FF
		OUT	($50), A

		LD A, 8
		OUT	($51), A
		LD A, 9
		OUT	($50), A

		LD A, 9
		OUT	($51), A
		LD A, 0
		OUT	($50), A

		LD A, $A
		OUT	($51), A
		LD A, 0
		OUT	($50), A

		LD A, 7
		OUT	($51), A
		LD A, $FE
		OUT	($50), A

		LD A, 1
		OUT	($51), A
		LD A, 1
		OUT	($50), A

		LD A, 0
		OUT	($51), A

		LD A, $FF
LOOP1		OUT	($50), A
		PUSH AF
		LD A, 8
		CALL DELAY
		POP AF
		DEC A
		JR NZ, LOOP1

 		LD A, 7
		OUT	($51), A
		LD A, $FF
		OUT	($50), A

		RET

; End of main code.

;Start of delay routine..
DELAY		PUSH BC
DLY_START	LD C, 10
DLY_LOOPO	LD B, 0
DLY_LOOPI	DJNZ DLY_LOOPI
		DEC C
		JR NZ, DLY_LOOPO
		DEC A
		JR NZ, DLY_START
		POP BC
		RET