Sound Blaster 16 Programming

Sound Blaster 16

	Introduction
	Overview
	IO Ports
	Resetting the DSP
	Available Modes
	Class Functions
	AutoDetecting Settings
	DSP Commands
	Sound Playback Ability
	Examples
	Download the PDF Version!

Introduction

I definitely encourage you to read or print all of this document. This data has changed the way not only how I look at hardware, but it also has given me the courage to say "screw that driver, I'll just program the hardware directly!" I have no idea how you ended up here, but let me say that we share the same pain and torment of using insufficient drivers and functions. Sometimes we just have to do things ourselves! This document goes hand in hand with the sound programming doc. Together you can build a Real-time Sound FX Mixing Machine!

Overview

If you are unfamiliar with programming hardware, then this section should be able to shed a little light on the mystery. Basically we are going to figure out information about the available sound card, given it is either a true Sound Blaster or a compatible card. With this information we can deduce what functions are available for us to use. From there we will begin to initialize the card and perform some simple functions using a mixture of outport (outp) commands and some additional information we get from the card itself. Specifically we know that the hardware uses a base io port that is given to us. Additions to that port number are the location of other ports specific to the SB. Maybe this will shed some light.
IO Ports
Later we will experiment with some different kinds of playback and sharpen our programming skills to manipulate the sound card the way WE want to :)

AutoDetecting SB Settings

Autodetecting is really kind of a cheap trick. We aren't doing any fancy hardware checking or any system checking. All we have to do is grab a system variable name BLASTER. Each Sound Blaster card has this system variable set in the autoexec.bat file. By grabbing this string and going through its various sections, we can get all the information we need to talk to the card.

Resetting the DSP

In order to reset the DSP we have to write a 1 to the RESET port, wait a few milliseconds and then write a 0 to the RESET port. After this we proceed to poll the DSPREAD port to see if it gives us the OK (DSP_READY signal). Immediately afterward we can request that the DSP give us its major and minor version numbers.

Available Modes

The DSP Version of your Sound Blaster card is the determining factor as to how you can output sound on the Sound Blaster. With the release of version 4.0+ programming has gotten a lot easier and a pretty wide variety of playback modes are supported, including 16 bit Stereo Auto Init playback! The following is a quick listing of all available modes and their appropriate DSP versions.

DMA Operation Mode	1.xx	2.00	2.01+	3.xx	4.xx

8 Bit Mono PCM Single Cycle
8 Bit Mono PCM Auto-Init

8 Bit Mono ADPCM Single Cycle
8 Bit Mono ADPCM Auto-Init

8 Bit Mono High Speed PCM Single Cycle
8 Bit Mono High Speed PCM Auto-Init

8 Bit Stereo High Speed PCM Single Cycle
8 Bit Stereo High Speed PCM Auto-Init

8/16 Bit Mono PCM Single Cycle
8/16 Bit Mono PCM Auto-Init
8/16 Bit Stereo PCM Single Cycle
8/16 Bit Stereo PCM Auto-Init

Sound Playback Ability

Here's a listing of what playback rates are available on which DSP versions!

DSP Version	Transfer Mode	Format	Sampling Range

4.xx	Mono	8 bit unsigned	5000 to 44100 Hz
	Mono	16 bit unsigned	5000 to 44100 Hz
	Stereo	8 bit unsigned	5000 to 44100 Hz
	Stereo	16 bit unsigned	5000 to 44100 Hz

3.xx	Mono	8 bit unsigned	4000 to 23000 Hz
	Mono/High Speed	8 bit unsigned	23000 to 44100 Hz
	Stereo/High Speed	8 bit unsigned	11025 to 22050

2.01+	Mono	8 bit unsigned	4000 to 23000 Hz
2.01+	Mono/High Speed	8 bit unsigned	23000 to 44100 Hz

2.00 and 1.xx	Mono	8 bit unsigned	4000 to 23000 Hz

ALL	Mono	8 bit to 4 bit ADPCM	4000 to 12000 Hz

ALL	Mono	8 bit to 3 bit ADPCM	4000 to 13000 Hz

ALL	Mono	8 bit to 2 bit ADPCM	4000 to 11000 Hz

IO Port Listing

IO Address	Description	Access
Base + 0h	FM Music Status Port	Read
Base + 0h	FM Music Register Address Port	Write
Base + 1h	FM Music Data Port	Write Only
Base + 2h	Advanced FM Music Status Port	Read
Base + 2h	Advanced FM Music Register Address Port	Write
Base + 3h	Advanced FM Music Data Port	Write Only
Base + 4h	Mixer Chip Register Address Port	Write Only
Base + 5h	Mixer Chip Data Port	Read / Write
Base + 6h	DSP Reset	Write Only
Base + 8h	FM Music Status Port	Read
Base + 8h	FM Music Register Port	Write
Base + 9h	FM Music Data Port	Write Only
Base + Ah	DSP Read Data Port	Read Only
Base + Ch	DSP Write Command/Data	Write
Base + Ch	DSP Write Buffer Status (Bit 7)	Read
Base + Eh	DSP Read Buffer Status (Bit 7)	Read Only
Base + 10h	CD-ROM Command or Data Register	Read / Write
Base + 11h	CD-ROM Status Register	Read Only
Base + 12h	CD-ROM Reset Register	Write Only
Base + 13h	CD-ROM Enable Register	Write ONly

Base Address	Memory Regions Used
220h	220h to 233h
240h	240h to 253h
260h	260h to 273h
280h	280h to 293h

DSP Command Listing (Only relevant modes displayed)

10h____8-bit Direct mode single byte digitized sound output
Input : 10h, Data (1 byte)
Notes : The user is responsible for calling this function at a relivant frequency. The user has to call this function and immediately follow it with the unsigned byte. Repeat this process until the end of the sound.

Availability

1.xx	2.00	2.01+	3.xx	4.xx
Yes	Yes	Yes	Yes	Yes

14h____8-bit Single-Cycle DMA mode digitized sound output
Input : 14h, LoByte(length-1), HiByte(length-1)Data (1 byte)
Notes : length is 1 WORD in length and is the number of 8-bit samples to be played.

Availability

1.xx	2.00	2.01+	3.xx	4.xx
Yes	Yes	Yes	Yes	Yes

1Ch____8-bit Auto-Init DMA mode digitized sound output
Input : 1Ch Notes :There are 2 ways of stopping Auto-Init Mode:
1) Switch to Single-Cycle DMA mode. The DSP after finishing its current block will process this command.
2) Send the exit Auto-Init mode command.(DAh)

Availability

1.xx	2.00	2.01+	3.xx	4.xx
No	Yes	Yes	Yes	Yes

20h____8-bit Direct mode single byte digitized sound input
Input : 20h Notes :The procedure to fetch data from the card is to 1)send command 0x20, 2) read a byte of digitized data from the DSP, 3) wait for the correct time period and repeat steps 1&2.

Availability

1.xx	2.00	2.01+	3.xx	4.xx
Yes	Yes	Yes	Yes	Yes

24h____8bit Single Cycle DMA mode digitiezed sound input
Input : 24h,Lo(length-1),Hi(length-1)
Notes : Length is a word giving the number of 8-bit samples.

Availability

1.xx	2.00	2.01+	3.xx	4.xx
Yes	Yes	Yes	Yes	Yes

2Ch____8-bit Auto-Init DMA mode digitized sound input
Input : 2Ch
Notes : Send 2Ch and GO!

Availability

1.xx	2.00	2.01+	3.xx	4.xx
No	Yes	Yes	Yes	Yes

40h____Set digitized sound transfer Time Constant
Input : 40h,TimeConst
Notes : TimeConst is calculated as follows:
TimeConst=65536 - (256 000 000/(channels * sampling rate))
channels is 1 for mono, and 2 for stereo. Only the high byte is sent to the DSP.
Availability

1.xx	2.00	2.01+	3.xx	4.xx
Yes	Yes	Yes	Yes	Yes

41h____Set digitized sound output sampling rate
Input : 41h,Hi(Sr),Lo(Sr)
Notes : Sr is the raw sampling rate from 5khz -> 45khz

Availability

1.xx	2.00	2.01+	3.xx	4.xx
No	No	No	No	Yes

42h____Set digitized sound input sample rate
Input : 42h,Hi(Sr),Lo(Sr)
Notes : See 41h

Availability

1.xx	2.00	2.01+	3.xx	4.xx
No	No	No	No	Yes

48h____Set DSP block transfer size
Input : 48h, Lo(Bs-1),Hi(Bs-1)
Notes : The DSP will generate an interrupt after each block of size Bs has been transfered. This command is used in high speed mode I/O and Auto-Init mode I/O

Availability

1.xx	2.00	2.01+	3.xx	4.xx
No	Yes	Yes	Yes	Yes

80h____Pause DAC for a duration
Input : 80h,Lo(Time-1),Hi(Time-1)
Notes : Time is the number of sampling periods. After the DAC has restarted it will generate an interrupt.

Availability

1.xx	2.00	2.01+	3.xx	4.xx
Yes	Yes	Yes	Yes	Yes

D0h____Pause 8-bit DMA mode digitizes sound output
Input : D0h
Notes : This will make the DSP to stop sending DMA requests. Continue output with command D4h.

Availability

1.xx	2.00	2.01+	3.xx	4.xx
Yes	Yes	Yes	Yes	Yes

D1h____Turn on the speaker
Input : D1h
Notes : On version 1.xx, the DSP will pause after executing this command. With version 4.xx, this serves only to set the speaker on/off flag so that the command D8 (get speaker status) works correctly. Command D3 will turn off the speaker.

Availability

1.xx	2.00	2.01+	3.xx	4.xx
Yes	Yes	Yes	Yes	Yes

D8h____Get Speaker Status
Input : D8h
Notes : After sending this command, read a byte from the DSP. A value of FFh indicates that the speaker is on, and 00h that it is off.

Availability

1.xx	2.00	2.01+	3.xx	4.xx
No	Yes	Yes	Yes	Yes

E1h____Get DSP Version Number
Input : E1h
Notes : After sending this command, read 2 bytes from the DSP. The first is the major version number, and the second is the minor version. It has been my experience that this command has to be executed immediately after the DSP has been reset to work.

Availability

1.xx	2.00	2.01+	3.xx	4.xx
Yes	Yes	Yes	Yes	Yes

Examples

Lesson 1 : Initilizing the DSP and Getting Environment Settings
Lesson 2 : Setting the Sound Blaster Mixer Levels
Lesson 3 : Reading the .Voc Format
Lesson 4 : Playback using Direct Mode
Lesson 5 : Playback using Single Cycle Mode
Lesson 6 : Playback using Auto-Init Mode

There are more examples that deal with the actual usage of the sound card, Lesson 6 is the last tutorial that deals with programming the card. The others teach the reader how to take that knowledge and build on it to achieve 3-d sound and special effects.