Editing Television Interface Adaptor (section)

==Noise/Tone Generator (AUD0/1)==
The TIA is capable of generating different types of [[pulse wave]]s and [[white noise]] output to its two [[Electronic oscillator|oscillators]] (or [[Audio signal|channels]]) AUD0 and AUD1. Each oscillator has a 5-bit [[frequency divider]] and a 4-bit audio control register which manipulates the [[waveform]]. There is also a 4-bit volume control register per [[Audio signal|channel]].

===Frequency Divider (AUDF0/1)===
[[Frequency|Frequencies]] are generated by taking 31399&nbsp;[[Hertz|Hz]] (31113&nbsp;[[Hertz|Hz]] for [[PAL]]) and dividing by the 5-bit value supplied.<ref name="flop">{{cite web |title=Sound Chips in 8-bit Computers |url=http://flop.atariportal.cz/content/62/en/ZVUKE1P1.html |website=FLOP Atari portal |access-date=14 December 2023}}</ref> 
The result is a cheap [[frequency divider]] capable of detuned notes and the odd tuned frequency. The TIA is not a musical chip unless the composer works within the frequency limits or modulates between two detuned frequencies to create a [[vibrato]] tuned note. The TIA is tuned to the inverted harmonic series due to each frequency being the base frequency divided by a whole number.

===Audio Control (AUDC0/1)===
The Audio Control register generates and manipulates a [[pulse wave]] to create complex [[Pulse (signal processing)|pulses]] or noise. The following tables (with designed duplicates) explains how its tones are generated:
{| border="2" cellpadding="3" style="margin-left:1em" class="wikitable"
|-
! HEX
! style="background-color:#C0C0C0" | D7
! style="background-color:#C0C0C0" | D6
! style="background-color:#C0C0C0" | D5
! style="background-color:#C0C0C0" | D4
! style="background-color:#00FFFF" | D3
! style="background-color:#00FFFF" | D2
! style="background-color:#00FFFF" | D1
! style="background-color:#00FFFF" | D0
! Type of noise or division
|-
| style="text-align:center" | 0
| rowspan="16" colspan="4" | &nbsp;
| style="text-align:center" | 0
| style="text-align:center" | 0
| style="text-align:center" | 0
| style="text-align:center" | 0
| Set to 1 (volume only)
|-
| style="text-align:center" | 1
| style="text-align:center" | 0
| style="text-align:center" | 0
| style="text-align:center" | 0
| style="text-align:center" | 1
| 4 bit poly
|-
| style="text-align:center" | 2
| style="text-align:center" | 0
| style="text-align:center" | 0
| style="text-align:center" | 1
| style="text-align:center" | 0
| '''÷''' 15 → 4 bit poly
|-
| style="text-align:center" | 3
| style="text-align:center" | 0
| style="text-align:center" | 0
| style="text-align:center" | 1
| style="text-align:center" | 1
| 5 bit poly → 4 bit poly
|-
| style="text-align:center" | 4
| style="text-align:center" | 0
| style="text-align:center" | 1
| style="text-align:center" | 0
| style="text-align:center" | 0
| '''÷''' 2
|-
| style="text-align:center" | 5
| style="text-align:center" | 0
| style="text-align:center" | 1
| style="text-align:center" | 0
| style="text-align:center" | 1
| '''÷''' 2
|-
| style="text-align:center" | 6
| style="text-align:center" | 0
| style="text-align:center" | 1
| style="text-align:center" | 1
| style="text-align:center" | 0
| '''÷''' 31
|-
| style="text-align:center" | 7
| style="text-align:center" | 0
| style="text-align:center" | 1
| style="text-align:center" | 1
| style="text-align:center" | 1
| 5 bit poly → '''÷''' 2
|-
| style="text-align:center" | 8
| style="text-align:center" | 1
| style="text-align:center" | 0
| style="text-align:center" | 0
| style="text-align:center" | 0
| 9-bit poly (white noise)
|-
| style="text-align:center" | 9
| style="text-align:center" | 1
| style="text-align:center" | 0
| style="text-align:center" | 0
| style="text-align:center" | 1
| 5-bit poly
|-
| style="text-align:center" | A
| style="text-align:center" | 1
| style="text-align:center" | 0
| style="text-align:center" | 1
| style="text-align:center" | 0
| '''÷''' 31
|-
| style="text-align:center" | B
| style="text-align:center" | 1
| style="text-align:center" | 0
| style="text-align:center" | 1
| style="text-align:center" | 1
| Set last 4 bits to 1
|-
| style="text-align:center" | C
| style="text-align:center" | 1
| style="text-align:center" | 1
| style="text-align:center" | 0
| style="text-align:center" | 0
| '''÷''' 6
|-
| style="text-align:center" | D
| style="text-align:center" | 1
| style="text-align:center" | 1
| style="text-align:center" | 0
| style="text-align:center" | 1
| '''÷''' 6
|-
| style="text-align:center" | E
| style="text-align:center" | 1
| style="text-align:center" | 1
| style="text-align:center" | 1
| style="text-align:center" | 0
| '''÷''' 93
|-
| style="text-align:center" | F
| style="text-align:center" | 1
| style="text-align:center" | 1
| style="text-align:center" | 1
| style="text-align:center" | 1
| 5-bit poly '''÷''' 6
|}

=== Instruments ===
Here is a table showing the instruments
{| class="wikitable"
|+
!Number
!Name
!Nickname
!Notes
|-
|1
|buzzy
|BASIC
|Basic [[atari]] sounds
|-
|2
|Buzzy/ramble
|Laser
|Sounds like a Jackhammer and a laser
|-
|3
|flangy/wavering
|[[Tremolo]]
|Has a [[tremolo]]
|-
|4
|pure
|[[Whistle]]
|Sounds like a whistle
|-
|6
|pure/buzzy
|[[trumpet]]
|Sounds like a trumpet
|-
|7
|reedy/rumble
|BASIC Jr.
|More basic [[atari]] sounds
|-
|8
|white noise
|[[Drum]]
|[[Percussion instrument|Percussion]] sounds
|-
|12
|pure lower
|Whistle Jr.
|More whistle sounds
|-
|14
|electronic/rumble
|Trumpet Jr.
|More Trumpet sounds
|-
|15
|electronic/rumble
|synth
|synth sounds
|}

=== Code ===
Shown is the code from combat<syntaxhighlight lang="asm" line="1">
MOTORS	LDA  AltSnd,X
	BEQ  DOMOTOR
	; Pong sound.
	LDA  #$04
	STA  AUDC0,X
	LDA  #$07
	STA  AUDV0,X
	LDA  BounceCount,X  
	STA  AUDF0,X
	RTS  
	; Engine sound.
DOMOTOR	LDY  GAMSHP
	LDA  SNDV,Y
	AND  GameOn             ; Kills sound if no game on by ANDing
	STA  AUDV0,X            ; volume value w/$00 no-game value
	LDA  SNDC,Y
	STA  AUDC0,X
	CLC  
	LDA  #$00
MOPIT0  DEY                     ; This loop sets start value for sound
	BMI  MOPIT1             ; pitch based on GAMSHP in Y (tank,
	ADC  #$0C               ; biplane, or jet)
	BPL  MOPIT0
MOPIT1  ADC  Vtemp,X            ; Use saved velocity to adjust
	TAY                     ; sound pitch via SNDP table
	TXA  
	ASL   
	ADC  SNDP,Y
	STA  AUDF0,X
	RTS  
</syntaxhighlight>