2 Programming the AdLib/Sound Blaster
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4 Version 2.0 (24 Feb 1992)
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6 Copyright (c) 1991, 1992 by Jeffrey S. Lee
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12 Warranty and Copyright Policy
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14 This document is provided on an "as-is" basis, and its author makes
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15 no warranty or representation, express or implied, with respect to
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16 its quality performance or fitness for a particular purpose. In no
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17 event will the author of this document be liable for direct, indirect,
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18 special, incidental, or consequential damages arising out of the use
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19 or inability to use the information contained within. Use of this
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20 document is at your own risk.
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22 This file may be used and copied freely so long as the applicable
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23 copyright notices are retained, and no modifications are made to the
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24 text of the document. No money shall be charged for its distribution
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25 beyond reasonable shipping, handling and duplication costs, nor shall
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26 proprietary changes be made to this document so that it cannot be
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27 distributed freely. This document may not be included in published
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28 material or commercial packages without the written consent of its
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35 Two of the most popular sound cards for the IBM-PC, the AdLib and the
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36 Sound Blaster, suffer from a real dearth of clear documentation for
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37 programmers. AdLib Inc. and Creative Labs, Inc. both sell developers'
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38 kits for their sound cards, but these are expensive, and (in the case
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39 of the Sound Blaster developers' kit) can be extremely cryptic.
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41 This document is intended to provide programmers with a FREE source
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42 of information about the programming of these sound cards.
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44 The information contained in this document is a combination of
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45 information found in the Sound Blaster Software Developer's Kit, and
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46 that learned by painful experience. Some of the information may not
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47 be valid for AdLib cards; if this is so, I apologize in advance.
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49 Please note that numbers will be given in hexadecimal, unless otherwise
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50 indicated. If a number is written out longhand (sixteen instead of 16)
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53 | Changes from Version 1 of the file will be indicated by the use of change
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54 | bars in the left-hand margin.
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58 Chapter One - Sound Card I/O
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60 The sound card is programmed by sending data to its internal registers
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61 via its two I/O ports:
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63 0388 (hex) - Address/Status port (R/W)
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64 0389 (hex) - Data port (W/O)
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66 | The Sound Blaster Pro is capable of stereo FM music, which is accessed
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67 | in exactly the same manner. Ports 0220 and 0221 (hex) are the address/
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68 | data ports for the left speaker, and ports 0222 and 0223 (hex) are the
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69 | ports for the right speaker. Ports 0388 and 0389 (hex) will cause both
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70 | speakers to output sound.
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72 The sound card possesses an array of two hundred forty-four registers;
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73 to write to a particular register, send the register number (01-F5) to
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74 the address port, and the desired value to the data port.
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76 After writing to the register port, you must wait twelve cycles before
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77 sending the data; after writing the data, eighty-four cycles must elapse
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78 before any other sound card operation may be performed.
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80 | The AdLib manual gives the wait times in microseconds: three point three
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81 | (3.3) microseconds for the address, and twenty-three (23) microseconds
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84 | The most accurate method of producing the delay is to read the register
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85 | port six times after writing to the register port, and read the register
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86 | port thirty-five times after writing to the data port.
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88 The sound card registers are write-only.
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90 The address port also functions as a sound card status byte. To
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91 retrieve the sound card's status, simply read port 388. The status
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92 byte has the following structure:
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95 +------+------+------+------+------+------+------+------+
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96 | both | tmr | tmr | unused |
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98 +------+------+------+------+------+------+------+------+
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100 Bit 7 - set if either timer has expired.
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101 6 - set if timer 1 has expired.
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102 5 - set if timer 2 has expired.
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106 Chapter Two - The Registers
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108 The following table shows the function of each register in the sound
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109 card. Registers will be explained in detail after the table. Registers
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110 not listed are unused.
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113 ------- ----------------------------------------------------
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114 01 Test LSI / Enable waveform control
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117 04 Timer control flags
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118 08 Speech synthesis mode / Keyboard split note select
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119 20..35 Amp Mod / Vibrato / EG type / Key Scaling / Multiple
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120 40..55 Key scaling level / Operator output level
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121 60..75 Attack Rate / Decay Rate
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122 80..95 Sustain Level / Release Rate
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123 A0..A8 Frequency (low 8 bits)
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124 B0..B8 Key On / Octave / Frequency (high 2 bits)
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125 BD AM depth / Vibrato depth / Rhythm control
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126 C0..C8 Feedback strength / Connection type
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129 The groupings of twenty-two registers (20-35, 40-55, etc.) have an odd
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130 order due to the use of two operators for each FM voice. The following
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131 table shows the offsets within each group of registers for each operator.
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134 Channel 1 2 3 4 5 6 7 8 9
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135 Operator 1 00 01 02 08 09 0A 10 11 12
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136 Operator 2 03 04 05 0B 0C 0D 13 14 15
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138 Thus, the addresses of the attack/decay bytes for channel 3 are 62 for
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139 the first operator, and 65 for the second. (The address of the second
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140 operator is always the address of the first operator plus three).
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142 To further illustrate the relationship, the addresses needed to control
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145 29 - Operator 1 AM/VIB/EG/KSR/Multiplier
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146 2C - Operator 2 AM/VIB/EG/KSR/Multiplier
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147 49 - Operator 1 KSL/Output Level
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148 4C - Operator 2 KSL/Output Level
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149 69 - Operator 1 Attack/Decay
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150 6C - Operator 2 Attack/Decay
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151 89 - Operator 1 Sustain/Release
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152 8C - Operator 2 Sustain/Release
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153 A4 - Frequency (low 8 bits)
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154 B4 - Key On/Octave/Frequency (high 2 bits)
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155 C4 - Feedback/Connection Type
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156 E9 - Operator 1 Waveform
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157 EC - Operator 2 Waveform
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161 Explanations of Registers
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163 Byte 01 - This byte is normally used to test the LSI device. All bits
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164 should normally be zero. Bit 5, if enabled, allows the FM
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165 chips to control the waveform of each operator.
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168 +-----+-----+-----+-----+-----+-----+-----+-----+
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169 | unused | WS | unused |
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170 +-----+-----+-----+-----+-----+-----+-----+-----+
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173 Byte 02 - Timer 1 Data. If Timer 1 is enabled, the value in this
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174 register will be incremented until it overflows. Upon
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175 overflow, the sound card will signal a TIMER interrupt
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176 (INT 08) and set bits 7 and 6 in its status byte. The
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177 value for this timer is incremented every eighty (80)
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181 Byte 03 - Timer 2 Data. If Timer 2 is enabled, the value in this
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182 register will be incremented until it overflows. Upon
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183 overflow, the sound card will signal a TIMER interrupt
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184 (INT 08) and set bits 7 and 5 in its status byte. The
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185 value for this timer is incremented every three hundred
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186 twenty (320) microseconds.
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189 Byte 04 - Timer Control Byte
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192 +-----+-----+-----+-----+-----+-----+-----+-----+
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193 | IRQ | T1 | T2 | unused | T2 | T1 |
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194 | RST | MSK | MSK | | CTL | CTL |
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195 +-----+-----+-----+-----+-----+-----+-----+-----+
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197 bit 7 - Resets the flags for timers 1 & 2. If set,
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198 all other bits are ignored.
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199 bit 6 - Masks Timer 1. If set, bit 0 is ignored.
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200 bit 5 - Masks Timer 2. If set, bit 1 is ignored.
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201 bit 1 - When clear, Timer 2 does not operate.
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202 When set, the value from byte 03 is loaded into
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203 Timer 2, and incrementation begins.
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204 bit 0 - When clear, Timer 1 does not operate.
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205 When set, the value from byte 02 is loaded into
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206 Timer 1, and incrementation begins.
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209 Byte 08 - CSM Mode / Keyboard Split.
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212 +-----+-----+-----+-----+-----+-----+-----+-----+
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213 | CSM | Key | unused |
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215 +-----+-----+-----+-----+-----+-----+-----+-----+
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217 bit 7 - When set, selects composite sine-wave speech synthesis
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218 mode (all KEY-ON bits must be clear). When clear,
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219 selects FM music mode.
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221 bit 6 - Selects the keyboard split point (in conjunction with
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222 the F-Number data). The documentation in the Sound
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223 Blaster manual is utterly incomprehensible on this;
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224 I can't reproduce it without violating their copyright.
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227 Bytes 20-35 - Amplitude Modulation / Vibrato / Envelope Generator Type /
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228 Keyboard Scaling Rate / Modulator Frequency Multiple
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231 +-----+-----+-----+-----+-----+-----+-----+-----+
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232 | Amp | Vib | EG | KSR | Modulator Frequency |
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233 | Mod | | Typ | | Multiple |
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234 +-----+-----+-----+-----+-----+-----+-----+-----+
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236 bit 7 - Apply amplitude modulation when set; AM depth is
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237 controlled by the AM-Depth flag in address BD.
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238 bit 6 - Apply vibrato when set; vibrato depth is controlled
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239 by the Vib-Depth flag in address BD.
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240 bit 5 - When set, the sustain level of the voice is maintained
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241 until released; when clear, the sound begins to decay
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242 immediately after hitting the SUSTAIN phase.
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243 bit 4 - Keyboard scaling rate. This is another incomprehensible
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244 bit in the Sound Blaster manual. From experience, if
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245 this bit is set, the sound's envelope is foreshortened as
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247 bits 3-0 - These bits indicate which harmonic the operator will
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248 produce sound (or modulation) in relation to the voice's
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249 specified frequency:
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251 0 - one octave below
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252 1 - at the voice's specified frequency
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253 2 - one octave above
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254 3 - an octave and a fifth above
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255 4 - two octaves above
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256 5 - two octaves and a major third above
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257 6 - two octaves and a fifth above
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258 7 - two octaves and a minor seventh above
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259 8 - three octaves above
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260 9 - three octaves and a major second above
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261 A - three octaves and a major third above
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263 C - three octaves and a fifth above
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265 E - three octaves and a major seventh above
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269 Bytes 40-55 - Level Key Scaling / Total Level
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272 +-----+-----+-----+-----+-----+-----+-----+-----+
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273 | Scaling | Total Level |
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274 | Level | 24 12 6 3 1.5 .75 | <-- dB
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275 +-----+-----+-----+-----+-----+-----+-----+-----+
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277 bits 7-6 - causes output levels to decrease as the frequency
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285 bits 5-0 - controls the total output level of the operator.
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286 all bits CLEAR is loudest; all bits SET is the
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287 softest. Don't ask me why.
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290 Bytes 60-75 - Attack Rate / Decay Rate
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293 +-----+-----+-----+-----+-----+-----+-----+-----+
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296 +-----+-----+-----+-----+-----+-----+-----+-----+
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298 bits 7-4 - Attack rate. 0 is the slowest, F is the fastest.
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299 bits 3-0 - Decay rate. 0 is the slowest, F is the fastest.
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302 Bytes 80-95 - Sustain Level / Release Rate
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305 +-----+-----+-----+-----+-----+-----+-----+-----+
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306 | Sustain Level | Release |
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307 | 24 12 6 3 | Rate |
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308 +-----+-----+-----+-----+-----+-----+-----+-----+
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310 bits 7-4 - Sustain Level. 0 is the loudest, F is the softest.
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311 bits 3-0 - Release Rate. 0 is the slowest, F is the fastest.
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314 Bytes A0-B8 - Octave / F-Number / Key-On
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317 +-----+-----+-----+-----+-----+-----+-----+-----+
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318 | F-Number (least significant byte) | (A0-A8)
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320 +-----+-----+-----+-----+-----+-----+-----+-----+
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323 +-----+-----+-----+-----+-----+-----+-----+-----+
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324 | Unused | Key | Octave | F-Number | (B0-B8)
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325 | | On | | most sig. |
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326 +-----+-----+-----+-----+-----+-----+-----+-----+
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328 bit 5 - Channel is voiced when set, silent when clear.
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329 bits 4-2 - Octave (0-7). 0 is lowest, 7 is highest.
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330 bits 1-0 - Most significant bits of F-number.
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332 In octave 4, the F-number values for the chromatic scale and their
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333 corresponding frequencies would be:
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335 F Number Frequency Note
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350 Bytes C0-C8 - Feedback / Algorithm
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353 +-----+-----+-----+-----+-----+-----+-----+-----+
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354 | unused | Feedback | Alg |
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356 +-----+-----+-----+-----+-----+-----+-----+-----+
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358 bits 3-1 - Feedback strength. If all three bits are set to
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359 zero, no feedback is present. With values 1-7,
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360 operator 1 will send a portion of its output back
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361 into itself. 1 is the least amount of feedback,
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363 bit 0 - If set to 0, operator 1 modulates operator 2. In this
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364 case, operator 2 is the only one producing sound.
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365 If set to 1, both operators produce sound directly.
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366 Complex sounds are more easily created if the algorithm
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370 Byte BD - Amplitude Modulation Depth / Vibrato Depth / Rhythm
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373 +-----+-----+-----+-----+-----+-----+-----+-----+
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374 | AM | Vib | Rhy | BD | SD | TOM | Top | HH |
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375 | Dep | Dep | Ena | | | | Cym | |
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376 +-----+-----+-----+-----+-----+-----+-----+-----+
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378 bit 7 - Set: AM depth is 4.8dB
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379 Clear: AM depth is 1 dB
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380 bit 6 - Set: Vibrato depth is 14 cent
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381 Clear: Vibrato depth is 7 cent
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382 bit 5 - Set: Rhythm enabled (6 melodic voices)
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383 Clear: Rhythm disabled (9 melodic voices)
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384 bit 4 - Bass drum on/off
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385 bit 3 - Snare drum on/off
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386 bit 2 - Tom tom on/off
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387 bit 1 - Cymbal on/off
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388 bit 0 - Hi Hat on/off
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390 Note: KEY-ON registers for channels 06, 07, and 08 must be OFF
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391 in order to use the rhythm section. Other parameters
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392 such as attack/decay/sustain/release must also be set
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396 Bytes E0-F5 - Waveform Select
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399 +-----+-----+-----+-----+-----+-----+-----+-----+
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400 | unused | Waveform |
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402 +-----+-----+-----+-----+-----+-----+-----+-----+
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404 bits 1-0 - When bit 5 of address 01 is set, the output waveform
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405 will be distorted according to the waveform indicated
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406 by these two bits. I'll try to diagram them here,
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407 but this medium is fairly restrictive.
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409 ___ ___ ___ ___ _ _
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410 / \ / \ / \ / \ / | / |
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411 /_____\_______ /_____\_____ /_____\/_____\ /__|___/__|___
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419 | Detecting a Sound Card
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421 | According to the AdLib manual, the 'official' method of checking for a
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422 | sound card is as follows:
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424 | 1) Reset both timers by writing 60h to register 4.
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425 | 2) Enable the interrupts by writing 80h to register 4. NOTE: this
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426 | must be a separate step from number 1.
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427 | 3) Read the status register (port 388h). Store the result.
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428 | 4) Write FFh to register 2 (Timer 1).
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429 | 5) Start timer 1 by writing 21h to register 4.
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430 | 6) Delay for at least 80 microseconds.
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431 | 7) Read the status register (port 388h). Store the result.
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432 | 8) Reset both timers and interrupts (see steps 1 and 2).
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433 | 9) Test the stored results of steps 3 and 7 by ANDing them
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434 | with E0h. The result of step 3 should be 00h, and the
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435 | result of step 7 should be C0h. If both are correct, an
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436 | AdLib-compatible board is installed in the computer.
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441 | Many people have asked me, upon reading this document, what the proper
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442 | register values should be to make a simple sound. Well, here they are.
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444 | First, clear out all of the registers by setting all of them to zero.
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445 | This is the quick-and-dirty method of resetting the sound card, but it
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446 | works. Note that if you wish to use different waveforms, you must then
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447 | turn on bit 5 of register 1. (This reset need be done only once, at the
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448 | start of the program, and optionally when the program exits, just to
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449 | make sure that your program doesn't leave any notes on when it exits.)
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451 | Now, set the following registers to the indicated value:
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453 | REGISTER VALUE DESCRIPTION
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454 | 20 01 Set the modulator's multiple to 1
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455 | 40 10 Set the modulator's level to about 40 dB
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456 | 60 F0 Modulator attack: quick; decay: long
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457 | 80 77 Modulator sustain: medium; release: medium
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458 | A0 98 Set voice frequency's LSB (it'll be a D#)
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459 | 23 01 Set the carrier's multiple to 1
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460 | 43 00 Set the carrier to maximum volume (about 47 dB)
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461 | 63 F0 Carrier attack: quick; decay: long
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462 | 83 77 Carrier sustain: medium; release: medium
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463 | B0 31 Turn the voice on; set the octave and freq MSB
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465 | To turn the voice off, set register B0h to 11h (or, in fact, any value
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466 | which leaves bit 5 clear). It's generally preferable, of course, to
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467 | induce a delay before doing so.
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472 | Thanks are due to the following people:
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474 | Ezra M. Dreisbach (ed10+@andrew.cmu.edu), for providing the information
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475 | about the recommended port write delay from the AdLib manual, and the
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476 | 'official' method of detecting an AdLib-compatible sound card.
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478 | Nathan Isaac Laredo (gt7080a@prism.gatech.edu), for providing the
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479 | port numbers for stereo sound on the Sound Blaster Pro.
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projects / 16.git / blob