Yamaha YM3806 Manual

Programmer’s Guide to Yamaha YM3806 (OPQ) FM
Synthesizer
Version 1.1 Feb 27, 2021
Written by Jari Kangas
This document can be distributed freely if not modified.
Summary
This document contains a rogrammer’s guide and a minimal data sheet for Yamaha OPQ
FM synthesizer chi s. The information a lies to YM3806 and very ro ably to YM3533
also.
isclaimer
Because most of the information resented here is based on reverse engineering, it is very
robable that there are misunderstandings and omissions. The writer assumes no
res onsibility for any damages arising out of use of this text. No warranty is rovided about
correctness of any information in this file.

OPQ Programmer’s Guide V 1.1 2
Table of Contents
1 Introduction.......................................................................................................................3
2 The OPQ synthesizer chi ................................................................................................3
3 OPQ synthesizer basics....................................................................................................5
3.1 O erators and channels............................................................................................5
3.2 Algorithms..................................................................................................................6
3.3 Triggering rinci les...................................................................................................6
3.4 Frequency settings....................................................................................................7
3.5 Envelo es..................................................................................................................7
3.6 Waveforms.................................................................................................................8
3.7 Timer and interru ts...................................................................................................8
4 Register structure..............................................................................................................9
4.1 Register address grou s............................................................................................9
4.2 Register grou s 2...7.................................................................................................9
4.3 Register grou 1......................................................................................................10
4.4 Register grou 0.......................................................................................................11
5 Register contents............................................................................................................12
5.1 Register addresses 00H...0FH................................................................................12
5.1.1 Register 00H: Status register (read-only).........................................................12
5.1.2 Register 03H: Timer control..............................................................................12
5.1.3 Register 04H: LFO control................................................................................13
5.1.4 Register 05H: Key-on/key-off triggers..............................................................13
5.2 Register addresses 10H...1FH................................................................................14
5.2.1 Registers 10H...17H: Algorithm / feedback / out ut channel...........................14
5.2.2 Registers 18H...1FH: Vibrato / tremolo / echo.................................................14
5.3 Register addresses 20H...3FH................................................................................15
5.3.1 Registers 20H...2FH: Octave / frequency hi-nibble..........................................15
5.3.2 Registers 30H...3FH: Frequency lo-byte..........................................................15
5.3.3 Octave and frequency numbering....................................................................15
5.4 Register addresses 40H...5FH................................................................................16
5.4.1 MSB = 0: Detune..............................................................................................16
5.4.2 MSB = 1: Frequency multi lier.........................................................................17
5.5 Register addresses 60H...7FH................................................................................17
5.5.1 Out ut attenuation............................................................................................18
5.6 Register addresses 80H...FFH................................................................................18
5.6.1 Registers 80H...9FH: Envelo e: attack rate / key scaler.................................18
5.6.2 Registers A0H...BFH: Envelo e: decay rate / waveform.................................19
5.6.3 Registers C0H...DFH: Envelo e: sustain rate..................................................19
5.6.4 Registers E0H...FFH: Envelo e: sustain level / release rate...........................20
6 OPQ register table..........................................................................................................21

OPQ Programmer’s Guide V 1.1 3
1 Introduction
This document contains a rogrammer’s guide and a minimal data sheet for Yamaha OPQ
FM synthesizer chi s. The information a lies to YM3806 and very ro ably to YM3533
also.
There is no official information available for these chi s. Everything resented in this
document is based on three sources:
•Reverse engineering of Yamaha PSR-70 keyboard, by the author
◦htt s://retroandreverse.blogs ot.com/search/label/PSR-70%20reverse
%20engineering
•Yamaha PSR-70 Owner’s Guide, by Yamaha Cor oration 1985
◦htt ://www.synthmanuals.com/manuals/yamaha/ sr-70/owners_manual /
•Yamaha PSR-70 Service Manual, by Yamaha Cor oration 1985
◦htt s://elektrotanya.com/yamaha_ sr-70_sm. df/download.html
One of the main information sources is the PSR-70 original internal software, which I have
studied closely. I will be referring to it several times with the term ”PSR-70 firmware”.
As a com arison and reference, I have used the more widely known OPL2/OPL3,
es ecially the excellent document ”Programmer's Guide to Yamaha YMF 262/OPL3 FM
Music Synthesizer” by Vladimir Arnost. Testing things using Dexed soft synth (”closely
modeled on the original DX-7 characteristics”) gave some insight. Also DX-11 seems to be
very close to OPQ in many res ects.
The OPQ is not that widely used, but it is found at least in PSR-60, PSR-70 and CLP-100
keyboards.
2 The OPQ synthesizer chip
The PSR-70 unit used for reverse engineering contains YM3806 chi , so all first-hand
information here is from this chi . The Service Manual uses also name YM3533
interchangeably, so it should be the same chi .
The chi is meant to be connected to normal rocessor bus. Data bus is 8-bit wide and
there are 8 address lines. Bus control signals are the normal RD, WR and CS. The chi
can also request an interru t.
OPQ chi contains no D/A-converter. It out uts two serial digital streams to an external
DAC. In PSR-70, an YM3012 is used for this ur ose. A datasheet for YM3012 is available
in internet.
There is no bus timing information available. In PSR-70, a Z80 CPU with 6 MHz clock is
used and the OPQ chi is ma ed as a art of memory address s ace. There is a wait-

OPQ Programmer’s Guide V 1.1 4
state logic im lemented in hardware, but to my understanding it is not used when
accessing the OPQ chi . This gives some rough idea about the bus timing s ecifications.
The chi comes in a 40- in DIP ackage and the inout is:
Pin functions:
VDD, VSS 5V su ly
D7...D0 Data bus from/to CPU
A7...A0 Address bus from CPU
WR, RD Write/read signals from CPU
CS, EN, EN Chi select and enable signals from address decoding. In PSR-70
only CS is used, EN and EN are connected ermanently active.
IRQ Interru t request to CPU
IC Inital clear ( = reset) from reset logic
SO, RSH, LSH Serial data out to DAC. In YM3012, signals SD, SAM1, SAM2
res ectively.
ø10 Clock out to DAC
X1, X2 Crystal. In PSR-70, a 3.579 MHz is used.

OPQ Programmer’s Guide V 1.1 5
Pins not mentioned above are not connected anywhere in PSR-70, so it is im ossible to
say anything about their ur ose.
3 OPQ synthesizer basics
Main s ecifications of the OPQ FM synthesizer:
•8 voice channels, i.e. 8 voice oly hony
•4 o erators er channel, so there are 32 o erators altogether
•8 algorithms
•se arate ADSR envelo e generator for each o erator
•one LFO, can be used for AM (tremolo) and FM (vibrato)
•mono honic (non-stereo) out ut
There is no ercussion mode nor ”sacrifice channel count and get more o erators er
channel”-modes as in OPL3. This makes OPQ more straightforward from rogrammer’s
oint of view.
The ”stereo or not stereo” question is quite clear: it is not stereo. The digital signals going
to the DAC are named LSH and RSH, which gives a clue of Left and Right, but it is better
to think that there are two se arate out ut channels, and each voice channel can be sent
to either of them or both. This can be useful for routing ur oses but it is not stereo. The
arrangement is similar to OPL3 synthesizer. Even PSR-70 does not use the out ut
channels as left and right, it uses them for controlling the effects routing.
3.1 Operators and channels
Against Yamaha tradition, I will be numbering everything starting from 0, also the
o erators.
This table summarizes which o erators form each channel’s channel-s ecific o erators:
Ch0 Ch1 Ch2 Ch3 Ch4 Ch5 Ch6 Ch7
O 0 0 1 2 3 4 5 6 7
O 1 8 9 10 11 12 13 14 15
O 2 16 17 18 19 20 21 22 23
O 3 24 25 26 27 28 29 30 31
Table 1. Operators
All four o erators of one channel are not equal:
•In all algorithms, O 3 is always a carrier, never a modulator. It is also kind of
”master o erator” regarding to triggering, see cha ter 3.3.

OPQ Programmer’s Guide V 1.1 6
•In all algorithms, O 0 is always a modulator, never a carrier. It is also the only
o erator which can use feedback. The feedback ossibility is indicated with the
feeback loo around O 0 in the algorithm icture on next age.
3.2 Algorithms
There are 8 algorithms to select from. The algorithms are resented in the following
icture.
3.3 Triggering principles
The o erator triggering scheme is quite different from OPL3. With triggering I mean turning
o erators on and off with their corres onding key-on bit. The main difference to OPL3 is
that the triggering is not done er channel, it is done er o erator. This means that even
same channel’s o erators can be turned on or off at different times. Turning o erator on
starts its envelo e’s attack hase and turning it off starts the release hase. This gives
quite a few new ossibilities in sound design. I have not noticed that PSR-70 firmware
would make use of this ossibility.
There are some limitations, though. As mentioned, O 3 acts as a master o erator: it must
always be triggered on, otherwise channel’s other o erators won’t trigger at all. Similarly,
when O 3 is triggered off, all other o erators will be triggered off at the same time. But
while O 3 is on, you can freely trigger other three o erators on and off, even several
times, if you want.

OPQ Programmer’s Guide V 1.1 7
Also during release hase O 3 affects on the other o erators: if O 3’s retrigger is disabled
and it has long release time, it will not retrigger before its out ut level has decreased near
zero. During that time any other same channel’s o erator won’t retrigger either, even if its
own release time has already ended.
3.4 Frequency settings
In OPQ each channel can have two different frequencies. Frequency is always set to an
o erator air, meaning that two of the channel’s o erators can use one frequency, while
two other can use com letely different frequency. The two frequencies do not need to be in
a harmonic relation, which again o ens u interesting ossibilities in sound design.
There is also ossibility to detune each o erator from its nominal frequency. And of course
the frequency multi lication is available as always in FM.
3.5 Envelopes
Each o erator has individually controllable envelo e curve. In fact, half of the registers are
used for the envelo e settings.
OPQ envelo e is a traditional ADSR-style envelo e with one added arameter, sustain
rate. During sustain hase the envelo e curve can also decrease, and sustain rate
controls the decrease rate. If sustain rate is 0, the sustain hase is horizontal (not
decreasing), and the the envelo e becomes basic ADSR. The curves are logarithmic in all
hases, but with small values of sustain rate the curve is ractically linear, as in the icture
below.

OPQ Programmer’s Guide V 1.1 8
Attack, decay and release are given as rates. Rate defines how fast the curve changes.
Larger rate = faster rise = shorter time. Also sustain rate is given as rate, but – as you
might ex ect – it does not affect sustain time, it affects the final level at the key-off
moment.
Sustain level defines the level, where the decay hase ends and sustain hase starts. So
it affects to decay time also.
It looks like Yamaha DX-11 envelo e system is exactly the same, just terminology differs.
What I call here ”sustain” they call ”decay2”.
3.6 Waveforms
Each o erator can have two different waveforms: sine and half-sine. Half-sine looks like
this:
3.7 Timer and interrupts
OPQ chi contains one timer, which can generate re eating interru ts. In PSR-70 this is
used as real-time interru t with 10 ms interval. I did not find out, how this is actually
controlled. I can get out 10 ms interru ts by mimicking the actions of the PSR-70 firmware,
but that’s all. I don’t know how to alter the interval, for exam le.
Timer is the only thing inside OPQ which can cause interru ts. Sound generation does not
use interru ts for anything.
The following cha ters 4 and 5 are the actual register reference.
•Cha ter 4 tries to answer questions like ”If I want to change attack rate of channel
4, o erator 2, which register address should I write to?”
•Cha ter 5 tries to answer questions like ”Now that I know the address, what is the
contents of the data I should write to that register to change the attack rate?”
While describing registers, we will need hex numbers. For that ur ose I will use the Intel/
Zilog originating style to use ostfix ’H’, like 0FH. If there is no ’H’, the number is decimal.

OPQ Programmer’s Guide V 1.1
4 Register structure
OPQ synthesizer has 256 8-bit registers, or at least 256 register addresses, not all have
any functionality. All registers are write-only, exce t register 00H, which is read-only.
One big difference to OPL3 is that all registers are directly addressable, because the chi
has 8 address lines. This makes writing and reading the registers sim ler, no need for two-
hase o erations.
The registers show u as 256 consecutive addresses in the controlling rocessor’s
address s ace. This may be memory address s ace or I/O address s ace, de ending on
the hardware designer’s decisions. In PSR-70, registers are in memory address s ace,
because Z80 has only 256 register I/O address s ace, so the OPQ chi would alone eat
u the whole I/O address s ace.
4.1 Register address groups
High level classification of registers can be done by grou ing the registers in grou s of 32
registers. The register grou number is the 3 most significant bits in the register address.
Register
grou nr
Register
adresses
Grou ’s functionality
0 00H...1FH General and channel s ecific settings
1 20H...3FH Frequency settings
2 40H...5FH Frequency multi lier/detune settings
3 60H...7FH Out ut level settings
4 80H...9FH Envelo e: attack rate settings
5 A0H...BFH Envelo e: decay rate settings
6 C0H...DFH Envelo e: sustain rate settings
7 E0H...FFH Envelo e: sustain level/release rate settings
Table 2. Register groups
Register grou s 0 and 1 need a bit more consideration, so lets look first at grou s 2...7,
which are more straightforward.
4.2 Register groups 2...7
In register grou s 2...7 all settings are o erator s ecific, meaning there is a register for
each of the 32 o erators and each o erator may have different settings. The lower 5 bits
of the register address can be thought as the o erator number (0...31) and it can be
ma ed to channel number (0...7) and o erator (O 0...O 3) using the table 1 on age 5.

OPQ Programmer’s Guide V 1.1 10
But I like to think this in even sim ler way. The setting can be written directly to s ecific
channel’s s ecific o erator by dividing address bits like this:
A7 A6 A5 A4 A3 A2 A1 A0
RG2 RG1 RG0 ON1 ON0 CN2 CN1 CN0
RG2...RG0 (2...7): Register grou number according to table 2.
ON1...ON0 (0...3): Channel’s o erator number, O 0...O 3.
CN2...CN0 (0...7): Channel number.
Exam les:
•Attack rate setting of Ch5, O 0: address = 85H
•Sustain rate setting of Ch1, O 3: address = D9H
4.3 Register group 1
Register grou 1 contains o erator frequency settings. These settings are not o erator
s ecific, they are o erator air s ecific. The o erator airs are O 1+O 3 and O 0+O 2
for each channel, so there are 16 o erator airs altogether.
Although there are only 16 frequencies to be set, two for each channel, register grou 1
still needs 32 registers. This is because each frequency is set by a 16-bit value, so there
must be a high byte and a low byte for each o erator air.
The address is formatted like this:
A7 A6 A5 A4 A3 A2 A1 A0
0 0 1 H P CN2 CN1 CN0
First three bits are 001, because this is register grou 1.
H: Is this the high or low byte of the 16-bit frequency value?
0 = high byte
1 = low byte
P: O erator air number
0 = O 1 + O 3
1 = O 0 + O 2
CN2...CN0: Channel number 0...7
Exam les:
•Frequency of Ch5, O 0 and O 2: hi-byte address = 2DH, lo-byte address = 3DH
•Frequency of Ch1, O 1 and O 3: hi-byte address = 21H, lo-byte address = 31H