Programming the SoundBlaster
| OFFSETS |
| Channel |
Carrier |
Modulator |
| 1 |
00h |
03h |
| 2 |
01h |
04h |
| 3 |
02h |
05h |
| 4 |
08h |
0Bh |
| 5 |
09h |
0Ch |
| 6 |
0Ah |
0Dh |
| 7 |
10h |
13h |
| 8 |
11h |
14h |
| 9 |
12h |
15h |
Add the offset to from the table above to the address of the register you
want to get all the register values.
Here are maps of the bits in each register. The upper-left cell of each
table will tell you what the base address of the register is. Add this
value to the offset of the table above to get the proper register value.
| 20h |
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Use |
AM |
Vibrato |
|
|
Octave Shift |
|
| 40h |
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Use |
Scaling |
Output Level |
|
| 60h |
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Use |
Attack Rate |
Decay Rate |
|
| 80h |
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Use |
Sustain Level |
Release Time |
|
In register 40h, scaling is how quickly the output level rises as the pitch
does. 0 = no rise, 1 = 1.5 dB/octave, 2 = 3 dB/octave, 3 = 6 dB/octave.
Output level is the volume. 63 is the lowest volume, 0 dB (muted) and 0,
the loudest volume, is 47 dB. This is not backwards. 0 is highest and 63
is lowest.
The Amplitude Modulation and Vibrato, if applied can be adjusted in
register BDh. Here is a bit map and explanation for register BDh. DO NOT
try to use the offsets with BDh to get different channels' settings, this
register sets the AM and Vibrato depths for all the channels.
| BDh |
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Use |
AM |
Vibrato |
When 6 is set, vibrato will be 14%. When bit 6 is clear, vibrato will be
7%. When 7 is set, AM will be 4.8 dB. When bit 7 is clear, AM will be 1
dB.
Here are the numeric representations of common music notes.
| Note |
Number |
| C# |
16Bh |
| D |
181h |
| D# |
198h |
| E |
1B0h |
| F |
1CAh |
| F# |
1E5h |
| G |
202h |
| G# |
220h |
| A |
241h |
| A# |
263h |
| B |
287h |
| C |
2AEh |
To set a note, you use the A0h and B0h registers. A0h is channel 1,
A1h is channel to, and so on up to A8h is channel 9. Same for B0h. Here
are bit maps of the registers.
| A0h |
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Use |
8 LSB of note |
| B0h |
| Bit |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
0 |
| Use |
n/a |
Switch |
Octave |
2 MSB |
Obviously, some explanations are needed. Bit 5 in B0h is the switch.
When set, the note starts playing, and when cleared, stops. Octave is just
that. MSB and LSB mean most significant byte and least significant byte,
respectively. The LSB are the last 2 digits of the note's hexadecimal (see
note values chart above) and the MSB is the first digit of the hexadecimal.
For example, G#'s MSB is 2h and it's LSB is 20h.
Here is a diagram of an FM sound showing the phases. X axis is time,
Y axis is volume.
Here are some CONST statements you can add right to your program:
CONST BaseAddr = &H220 'Change if your sound card uses another base address
CONST RegAddr = BaseAddr + 8, DataAddr = BaseAddr + 9
Those should work. Just remember RegAddr = BaseAddr + 8, and DataAddr =
BaseAddr + 9. You may want to create a SUB called SetReg so you don't have
to type the actual OUT statements, just SetReg reg%, data%. In the SetReg
SUB, put 2 OUT statements, like this:
SUB SetReg (Reg, Value)
OUT RegAddr, Reg
OUT DataAddr, Value
END SUB
Just use that code and it should work.