Use the OPL3 YMF262

The YMF262 is inside the FPGA of some machines

The F256 machines, except the F256Jr., have in their Beatrix FPGA a YMF262 capable of Yamaha OPL3 that uses up to 36 operators. You can also use it in compatible OPL2 that uses a subset of up to 18 operators

F256 registers for 6502, 65816, 6809(?) cores

Register Name	Address	Description
OPL_ADDR_L	0xD580	Register for addressing ports 0x000 to 0x0FF
OPL_DATA	0xD581	Data register for all ports
OPL_ADDR_H	0xD582	Register for addressing ports 0x100 to 0x1FF

Usage:

When targetting a port in the 0x000 - 0x0FF range, send the port byte to 0xD580, then its data byte to 0x581.

When targetting a port in the 0x100 - 0x1FF range, send the port byte masked with 0x0FF to 0xD582, then its data byte to 0xD581.

Example 1: to start the chip using port 0x01, send 0x01 to 0xD580, then 0x01 to 0xD581.

Example 2: to enable OPL3 using port 0x105, send 0x05 to 0xD582, then 0x01 to 0xD581.

Chip wide ports

Port Name	Port Address	Description	B7	B6	B5	B4	B3	B2	B1	B0
Test Register / Waveform Select Enable	0x01	Must be used to "start the chip"	Test Register		Wave Select Enable	Test Register
		Set all Test Register bits to 0 to start the chip. B5 clear = all sine waves B5 set= enables wave choices in 0xE0-F5
Timer 1 Count	0x02	8bit timer with resolution of 80 us.
		If overflow occurs, status register is set and preset value is loaded
Port Name	Port Address	Description	B7	B6	B5	B4	B3	B2	B1	B0
Timer 2 Count	0x03	8bit timer with resolution of 320 us.
		If overflow occurs, status register is set and preset value is loaded
IRQ-Reset/Mask/Start	0x04	Timer controls	Reset	T1Mask	T2Mask	-	-	-	T2Start	T1Start
		B7 resets and IRQ flags status reg and ignore all others when this is set B6 timer 1 mask. status reg is not affected in overflow B5 timer 2 mask. same for timer2 B1 Timer 2 start. timer on/off B0 Timer 1 start, same
Port Name	Port Address	Description	B7	B6	B5	B4	B3	B2	B1	B0
Four-Operator Enable	0x104	Sets up four-operator channels	-	-	4-OP B-E	4-OP A-D	4-OP 9-C	4-OP 2-5	4-OP 1-4	4-OP 0-3
		When fully set 0, 18 two-operator pairs are formed. When non-zero, four-operators are formed at specific locations B5: channels 11-14 (decimal) are grouped B4: channels 10-13 B3: channels 9-12 B2: channels 2-5 B1: channels 1-4 B0: channels 0-3
OPL3 Mode Enable	0x105	enables OPL3 extensions	-	-	-	-	-	-	-	Enable
		set B0 to enable 36 operators, 4-OP synth, 8 waveforms, stereo output. When cleared, OPL2 is enabled.
Port Name	Port Address	Description	B7	B6	B5	B4	B3	B2	B1	B0
Tremolo/Vibrato/Percussion	0xBD	Bits 0-4 are treated as key-on/key-offs.	Tre	Vib	Perc Mode	BassDrum	SnareDrum	Tom-Tom	Cymbal	Hi-Hat
		B7 and B6 set = more present effect. B5 being set enables these 4 default percussive instruments When using B0-B4, key-on in channels 6,7,8 and their fnums have to be cleared! Their ADSR must be appropriate This register is only used in OPL2 lower half, it does not affect higher half OPL3.

Channel wide ports

Port Name	Port Address	Description	B7	B6	B5	B4	B3	B2	B1	B0
Frequency Number (LO)	0xA0	The first 8 out of 10 bits of frequency value	Frequency Number (L)
		One only needs to generate 12 semi-tones once and use them over and over for western equal temperament music {0x205, 0x223, 0x244, 0x267, 0x28B, 0x2B2, 0x2DB, 0x306, 0x334, 0x365, 0x399, 0x3CF} this array also includes the top 2 bits used in the next register base of 0xB0.
Key On - Freq Block - Freq Num (Hi)	0xB0	Last 2 out of 10 bits of frequency value.	-	-	Key On	Freq Block			FNum (H)
		Key On toggles in the playing of the note on/off. Block kinda switches octaves
Feedback - Algorithm	0xC0		OutChD	OutChB	R	L	Feedback			Synth
		Digital audio outputs R = right speaker, L = left speaker, B = 3rd output, D = 4th output Feedback: sends a portion of its output back to itself if set between value of 1-7 Synthesis types: Op 1&2 Op 3&4 Type 0 None FM 1 None AM 0 0 FM-FM 1 0 AM-FM 0 1 FM-AM 1 1 AM-AM

Operator wide ports

Port Name	Port Address	Description	B7	B6	B5	B4	B3	B2	B1	B0
Various Effects	0x20		Tremolo	Vibrato	Sus	KSR	Multiplication
		Tremolo and Vibrato turn the effects on and off Sustain until key off Enveloppe scaling KSR, when 1, higher notes are shorter than lower notes Bits 0-3: Frequency Mutiplication, adds a multiplication coefficient to the note frequency multi 0 is a factor of 0.5 multi 1 is 1 multi 2 is 2 and so on
KSL and output levels	0x40		KSL 0-3		Output Level 0-32
		Key Scale Level is the attenuation of output level at higher pitch KSL 0 : none KSL 1: 3dB/octave, KSL 2: 1.5 dB/octave, KSL 3: 6.0 dB/octave Output level works in reverse: 0 is the loudest, 0x3F is the softest.
Port Name	Port Address	Description	B7	B6	B5	B4	B3	B2	B1	B0
Attack and Decay	0x60		Attack 0x00 to 0x0F				Decay 0x00 to 0x0F
Sustain and Release	0x80		Sustain 0x00 to 0x0F				Release 0x00 to 0x0F
Waveform select	0xE0							Waveform
		Chip wide register 0x01's bit 5 must be set to 1 to enable all of the following Waveforms of 4-7 are only available with OPL3 Value Type 0 Sine 1 Half-sine 2 Absolute value sine 3 Pulse Sine 4 Sine with even periods only 5 Absolute sine with even periods only 6 Square 7 Derived Square

Accessing all the operators

In order to access all the operator's registers, you must apply an offset to all of the previous addresses from the above section, which were all relevant to operator 0.

Here are a couple of examples to help visualize this:

	Operators of bank 0 (OPL2 and OPL3)
	Channel 1		Channel 2		Channel 3		Channel 4		Channel 5		Channel 6		Channel 7		Channel 8		Channel 9
Operators---->	1	4	2	5	3	6	7	10	8	11	9	12	13	16	14	17	15	18
Modulator or Carrier ---->	M1	C1	M2	C2	M3	C3	M4	C4	M5	C5	M6	C6	M7	C7	M8	C8	M9	C9
Register for Various Effects	0x20	0x23	0x21	0x24	0x22	0x25	0x28	0x2B	0x29	0x2C	0x2A	0x2D	0x30	0x33	0x31	0x34	0x32	0x35
Register for KSL and output levels	0x40	0x43	0x41	0x44	0x42	0x45	0x48	0x4B	0x49	0x4C	0x4A	0x4D	0x50	0x53	0x51	0x54	0x52	0x55

For OPL3, these addresses for channels 10 to 18 are the same, but you need to send these registers to 0xD582 (instead of 0xD580), then the value to 0xD581.