#5fps -Draw every 12th frame-
<condition>5fpsAnimFrame00,frameRange,60,48
<condition>5fpsAnimFrame01,frameRange,60,36
<condition>5fpsAnimFrame02,frameRange,60,24
<condition>5fpsAnimFrame03,frameRange,60,12
<condition>5fpsAnimFrame04,frameRange,60,0

[5fpsAnimFrame00]<background>Liquids\08-09_lava-frame00.png,1,1,1,10,0,0
[5fpsAnimFrame01]<background>Liquids\08-09_lava-frame01.png,1,1,1,10,0,0
[5fpsAnimFrame02]<background>Liquids\08-09_lava-frame02.png,1,1,1,10,0,0
[5fpsAnimFrame03]<background>Liquids\08-09_lava-frame03.png,1,1,1,10,0,0
[5fpsAnimFrame04]<background>Liquids\08-09_lava-frame04.png,1,1,1,10,0,0


---

4fps -Draw every 15th frame-
<condition>4fpsAnimFrame00,frameRange,60,45
<condition>4fpsAnimFrame01,frameRange,60,30
<condition>4fpsAnimFrame02,frameRange,60,15
<condition>4fpsAnimFrame03,frameRange,60,0

[4fpsAnimFrame00]<tile>7,200,FF18362A,640,8,1,N
[4fpsAnimFrame01]<tile>7,200,FF18362A,672,8,1,N
[4fpsAnimFrame02]<tile>7,200,FF18362A,704,8,1,N
[4fpsAnimFrame03]<tile>7,200,FF18362A,736,8,1,N

      

spriteFrameRange

The spriteFrameRange conditions can be used to conditionally replace sprite tiles based on the number of frames have passed since the sprite is visible on screen. The condition is true when the following expression is true:
[number of frames have passed] % [divisorValue] >= [compareValue]

Syntax: <condition>[name - text], spriteFrameRange, [divisorValue - integer], [compareValue - integer]
Example: <condition>myCondition,spriteFrameRange,8,10 (This condition will be true for the last 2 frames out of every 10 frames since the sprite is visible)

randomBackground

The randomBackground conditions can be used to randomly replace background tiles with a given probability. The condition is true when the following expression is true:
[random number between 0 and 1 assigned to the tile] <= [compareValue]

Syntax: <condition>[name - text], randomBackground, [compareValue]
Example: <condition>myCondition,randomBackground,0.1 (This condition will be true for 10% of the background tiles)

<tile> tag

Syntax: <tile>[img index - integer], [tile data], [palette data], [x - integer], [y - integer], [brightness - float (default: 1.0)], [default tile - Y or N]
Example (CHR ROM): <tile>0,2E,FF16360F,0,0,1,N
Example (CHR RAM): <tile>0,0E0E079C1E3EA7076101586121010000,0F100017,176,1168,1,N

For CHR ROM games, tile data is an integer (in hexadecimal) representing the position of the original tile in CHR ROM.
For CHR RAM games, tile data is a 32-character hexadecimal string representing all 16 bytes of the tile.
palette data is always an 8-character hexadecimal string representing all 4 bytes of the palette used for the tile. For sprites, the first byte is always “FF”.

<tile> define mappings between the original game’s tile data and their replacements in the PNG file. The tile data and palette data are used to identify the original tile, while the img index, x and y fields are used to specify in which PNG file the replacement can be found, and at what x,y coordinates in that PNG file.

brightness can be used to reuse the same HD tile for multiple original tiles – this can be useful when a game has fade in and out effects (the brightness can be set to values above 1.0 to increase the PNG’s normal brightness level).
When default tile is enabled (with Y), the tile is marked as the default tile for all palettes. Whenever a tile appears on the screen that matches the tile data, but has no rules matching its palette data, the default tile will be used instead.

<addition> tag

Syntax: <addition>[tile data], [palette data], [distance x - integer], [distance y - integer], [additional tile data], [additional palette data], [default (pallet) - Y or N]
Example (CHR ROM): <addition>2E,FF16360F,12,-10,FF,FF000000,N
Example (CHR RAM): <addition>0E0E079C1E3EA7076101586121010000,0F100017,0,30,00000000000000000000000000000000,FF123456,N

For CHR ROM games, tile data is an integer (in hexadecimal) representing the position of the original tile in CHR ROM.
For CHR RAM games, tile data is a 32-character hexadecimal string representing all 16 bytes of the tile.
palette data is always an 8-character hexadecimal string representing all 4 bytes of the palette used for the tile. For sprites, the first byte is always “FF”.

<addition> define one additional tile to be shown when a matching sprite tile is found. The distance x and distance y parameters define where it will be shown. The additional tile data and additional palette data parameters define how the additional tile is identified. The tile can only be shown by using <tile> tag to specify the replacement.

<fallback> tag

Syntax: <fallback>[new tile data], [fallback to tile data]

Using "<fallback>85E,25E" and "<fallback>>145E,25E" as an example, the "85E" and "145E" are addresses that "fall back" onto the "25E" address.
This means that whenever the game encounters "145E" or "85E" the game will use the graphics specified for "25E" unless stated otherwise.
It's like a cross reference sheet, It's useful for some games that have duplicate graphics. ex: In Metroid, the missile graphic address is different depending on your location.

<background> tag

Syntax: <background>[name - text], [brightness level - float (default: 1.0)], [horizontal scroll ratio (optional) - float], [vertical scroll ratio (optional) - float], [priority level (optional) - int, 0 to 39 (default 10)], [image left offset (optional) - int], [image top offset (optional) - int]
Example: <background>myBackground.png,1.0,0,0,10,0,0

<background> tags are meant to be used alongside conditions to add a background image under certain conditions (e.g on a specific screen, for example).

The Horizontal Scroll Ratio and Vertical Scroll Ratio parameters are optional (their default value is 0.0) and can be used to specify at what speed the background picture should scroll compared to the NES’ scrolling.
This can be used to create simple parallax scrolling effects.

The Image Left Offset and Image Top Offset parameters are optional (their default value is 0) and can be used to offset the position of the background image within the PNG file. e.g: Specifying 100 for the left offset will cause the background to be scrolled 100 pixels to the left by default. With conditions, this can be used to create scrolling effects that are based on something other than the PPU’s current scroll offset.

The Priority Level parameter determines where the background is inserted compared to the NES’ 3 “layers” (background sprites -> background tiles -> foreground sprites).
The screen is drawn in this order:

• Priority 0 to 9 HD backgrounds (priority 0 is below priority 1, etc.)
• Background-priority sprites
• Priority 10 to 19 HD backgrounds
• Background tiles
• Priority 20 to 29 HD backgrounds
• Foreground-priority sprites
• Priority 30 to 39 HD backgrounds

Note: Only a single background can be active per priority level.

Backgrounds can use a PNG’s alpha channel to allow the graphics below to show through them (this can be used to add a fog effect to the screen, etc.)

<options> tag

Syntax: <options>[option1 - text], [option2 - text], [...]
Example: <options>disableSpriteLimit

Available options:

disableSpriteLimit: Forces the emulator to disable the sprite limit when the HD pack is loaded.

disableOriginalTiles: Normally, when a replacement for a tile is not found, the original tile is drawn. When this option is enabled, the original tiles are never drawn, only their HD replacements.

automaticFallbackTiles: Mesen will try to automatically detect duplicate graphics. (also see <fallback>)

<bgm> tag

Syntax: <bgm>[album - integer],[track - integer],[filename - ogg],[loop point (optional) - integer],[playback option (optional) - integer],[volume (optional) - integer]
Example: <bgm>0,0,myBgm.ogg
Example (with optional values): <bgm>0,0,myBgm.ogg,40000,1,-1

Loop point: The sample number in the ogg file where the track will loop back to. Playback option: Use 1 for looping playback, 0 for single playback, -1 for keeping the current value. Volume: Use 0 to 128 for changing the volume, -1 for keeping the current volume.

Used to assign a background music track (.ogg audio file) to a specific album and track number. Album and track numbers are used to form a unique ID for each bgm, allowing up to 64k different bgm tracks.

<sfx> tag

Syntax: <sfx>[album - integer],[track - integer],[filename - ogg]
Example: <sfx>0,0,myBgm.ogg

Used to assign a sound effect (.ogg audio file) to a specific album and track number. Album and track numbers are used to form a unique ID for each sound effect, allowing up to 64k different sound effects.

Using conditions

To use conditions, add the condition’s name at the start of the line. e.g:
[myConditionName]<tile>...

Conditions can only be applied to <tile> or <background> tags. When a condition is applied to a <tile> or <background> tag, that rule will only be used if the condition is met.

The first matching rule (in the order they are written in the hires.txt file) will be used. So conditional tiles MUST be placed before tiles with no conditions (for the same tile data+palette data) to have any effect.

You can also make it so multiple conditions must be met for a rule to be used by joining each condition name with a &:
[cond1&cond2]<tile>...

It is also possible to invert the result of a condition by prepending a an exclamation mark (!) to it:
[!myCondition]<tile>...

Replacing audio in games

Audio replacement in HD packs in Mesen works in a similar fashion to the MSU-1 for the SNES.
It adds a number of read/write registers in memory and they can be used to play OGG files specified via <bgm> and <sfx> tags.

NES APU

      
    ; SILENCE ALL NES AUDIO
    
    	        LDA #%00000000
        	STA $4015     ; PUSH #%00000000 to $4015 (NES APU Control / Status)
		                       ||||||||      
				       |||||||+-- BIT 0 - DPCM IRQ (0=DISABLE / 1=ENABLE)
				       ||||||+--- BIT 1 - Square 1 (0=DISABLE / 1=ENABLE)
				       |||||+---- BIT 2 - Square 2 (0=DISABLE / 1=ENABLE)
				       ||||+----- BIT 3 - Triangle (0=DISABLE / 1=ENABLE)
				       |||+------ BIT 4 - Noise    (0=DISABLE / 1=ENABLE)
				       ||+------- BIT 5 - DPCM     (0=DISABLE / 1=ENABLE)
				       |+-------- BIT 6 - (unused - always 0)
				       +--------- BIT 7 - (unused - always 0)
				            
$4015 is the APU Channel Enable Register on the NES.
It turns ON/OFF each audio channel:

Square 1
Square 2
Triangle
Noise
DPCM (sample channel)

When a bit = 1 → channel ON
When a bit = 0 → channel OFF / force silent

It is write-only, but can be read to check DPCM / IRQ status.

WRITE TO $4015 (mute or enable channels)
bit 7 --- unused (always 0)
bit 6 --- unused (always 0)
bit 5 --- DPCM enable
bit 4 --- Noise enable
bit 3 --- Triangle enable
bit 2 --- Square 2 enable
bit 1 --- Square 1 enable
bit 0 --- DPCM IRQ enable (on write) / status flag on read

✔ NES use for enabling channels:
Bit	Hex Value	Channel	Common Use
0	$01	DPCM IRQ	Rarely used
1	$02	Square 1	Music melody, sometimes SFX
2	$04	Square 2	Music harmony, sometimes SFX
3	$08	Triangle	Bassline, Mario jumps, etc.
4	$10	Noise	SFX (explosion, bump, etc.)
5	$20	DPCM sample	Sample playback in cutscenes

Bits 6–7 do nothing.
				            
      

      
    ; NEA ENABLE LOOP BGM 
		LDA #$01    ; LOOP ENABLE
		STA $4100   ; PUSH 01(LOOP) to $4100
		
OR

    ; NEA DISABLE LOOP BGM
		LDA #$00    ; LOOP DISABLE
		STA $4100   ; PUSH 00(NO LOOP) to $4100

      

      
    ; NEA PAUSE
		LDA #%00000001 ; PAUSE - STOP BGM
		STA $4101      ; PUSH #%00000001 to $4101


    ; NEA RESUME
		LDA #%00000000 ; PAUSE - RESUME
		STA $4101      ; PUSH #%00000000 to $4101
		                      	     |||      
					     ||+-- BIT 0 - When set, pauses/resumes the BGM track.
					     |+--- BIT 1 - When set, the BGM track is stopped.
				             +---- BIT 2 - When set, all SFX tracks are stopped.
				             			
      

CPU Memory Map
$FFFA - $FFFF is where all of your interrupts are located such as NMI, RESET, and IRQ
$8000 - $FFF9 is the PRG-ROM, which basically means it's where all of your programming data will be located in, 32K of it. Larger programs can perform bank switching to execute other code.
$6000 - $7FFF even though it says SRAM, I personally call it WRAM because it's Work Ram.
$4018 - $5FFF is the expansion ROM, which is for the expansion located on the bottom of the NES. These addresses are never used due to the fact that no expansion device was ever made for it!
$4017 Controller 2 plus IRQ interrupts
$4016 Controller 1
$4015 APU Sound/Vertical Clock Signal Register
$4014 Sprite DMA Register (Direct Memory Access)
$4013 APU Delta Modulation Data Length Register
$4012 APU Delta Modulation Address Register
$4011 APU Delta Modulation D/A Register
$4010 APU Delta Modulation Control Register
$400F APU Noise Frequency Register 2
$400E APU Noise Frequency Register 1
$400D Not Used
$400C APU Noise Control Register 1
$400B APU Triangle Frequency Register 2
$400A APU Triangle Frequency Register 1
$4009 APU Triangle Control Register 2
$4008 APU Triangle Control Register 1
$4007 APU Pulse 2 Coarse Tune Register
$4006 APU Pulse 2 Fine Tune Register
$4005 APU Pulse 2 Ramp Control Register
$4004 APU Pulse 2 Control Register
$4003 APU Pulse 1 Coarse Tune (CT) Register
$4002 APU Pulse 1 Fine Tune (FT) Register
$4001 APU Pulse 1 Ramp Control Register
$4000 APU Pulse 1 Control Register
$2008 - $3FFF are mirrors of $2000-$2007 over and over again. Any data changed between $2000-$2007 will be copied in $2008-$3FFF and vice versa, hence the term "mirroring".
$2007 VRAM I/O Register
$2006 VRAM Address Register 2
$2005 VRAM Address Register 1
$2004 SPR-RAM I/O Register
$2003 SPR-RAM Address Register
$2002 PPU Status Register
$2001 PPU Control Register 2
$2000 PPU Control Register 1
$0800 - $1FFF are mirrors of $0000-$07FF over and over again.
$0300 - $07FF is RAM
$0200 - $02FF is where your sprite data from your CHR file is stored. Note that more sprite data can be swapped using bank switching so you are not limited.
$0100 - $01FF is the stack, and generally used for arrays I believe.
$0000 - $00FF is known as the Zero Page. Generally, variables can be declared here.