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general:guides:hxd_guide

HxD Hex Guide

By FelixWright, A.K.A. Cosmic

Hello, and welcome to our current graphics guide for HxD and hex editing in general.

The main goal of this guide is to teach newbies how to edit ROMs with hexadecimal.

Let's get started.

What is HxD?

HxD is a hex editor, disk editor, and memory editor developed for Windows. HxD can open files larger than 4 GiB and open and edit the raw contents of disk drives, as well as display and edit the memory used by running processes. Among other features, it can calculate various checksums, compare files, or shred files. The most recent version was created in 2009 by Maël Hörz.

Downloading HxD

HxD 2.0 RC can be downloaded from mh-nexus.

What is Hexadecimal?

To understand hexadecimal, you need to understand decimal. Decimal (also called base-ten, and occasionally called denary) is the standard system for denoting integer and non-integer numbers. Decimal is called base10 because it uses ten values: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. Because it is the de-facto standard number system, it does not have any denotation.

Example: 100 in Decimal is 100.

Hexadecimal is a positional numeral system with a radix, or base, of 16. This means it uses sixteen symbols, in this case 0–9 to represent values zero to nine, and A–F to represent values ten to fifteen. In the romhacking scene, hex values are denoted with $ or 0x. Less commonly, you may also see a hexadecimal number denoted by a trailing h, although it is not recommended to write it this way yourself unless you know what you're doing, as it is lesser known.

Example: 100 in Hexadecimal is $64, 0x64, or less commonly, 64h.

More examples:

DECIMAL  =  0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

    HEX  =  0 1 2 3 4 5 6 7 8 9 A  B  C  D  E  F  10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F

There are many online resources for converting hex to decimal, but in this tutorial I will explain how to convert hex to decimal and decimal to hex using windows calculator. Before we begin, run calc.exe and press Alt + 3. This will put the calculator in programming mode.

Converting Hex to decimal

Select the “Hex” Bubble.

Paste in your hex value (Ctrl + V) or type it in. Select the “Dec” Bubble.

Ctrl + C to copy converted value to clipboard.

Converting decimal to Hex

Select the “Dec” Bubble.

Paste in your dec value (Ctrl + V) or type it in. Select the “Hex” Bubble.

Ctrl + C to copy converted value to clipboard.

Using HxD

Keyboard Shortcuts

Before we get into hex editing you should learn keyboard shortcuts. For ROMHacking, here's what you will need to know:

Key Combination Description
F3 Find Again
F6 Next Difference (File Compare)
Delete Clear Selection (Note: This shortens filesize!)
CTRL + A Select All
CTRL + E Select Block…
CTRL + G Go To…
CTRL + K File Compare…
CTRL + N New file (Empty)
CTRL + C Copy Selection
CTRL + X Cut Selection
CTRL + V Paste Insert (Note: This increases filesize!)
CTRL + B Paste Write (Overwrite)
CTRL + Z Undo
CTRL + Y Redo
CTRL + O Open a file…
CTRL + R Find & Replace…
CTRL + S Save a file
Shift + F3 Find Again (Reverse)
Shift + F6 Previous Difference (File Compare)
Ctrl + F4/Ctrl + W Close file
Ctrl+Number (0-9) Goto bookmark
Ctrl+Shift+Number (0-9) Add bookmark
Left and Right Arrow keys Move to next/previous byte
Up and Down Arrow keys Move to next/previous row
Shift + Up/Shift + Down Select next/previous row
Shift + Left/Shift + Right Select next/previous byte

WARNING: Changes in filesize could destroy your ROM if you're not careful!

Going to an offset

Going forward, Let's say you want to disable the low energy alarm in Zero Mission. 0x52888 = 1D 2F to 14 E0

Open Zero Mission in HxD, and use Goto… (Ctrl + G)

As you can see, by default HxD assumes you want to put in a hex address, and the address above is hex so that is fine. If you run into a decimal or octal address though, you can select the dec or oct bubbles and then paste in the address.

Editing Hex Values

So we're at address 0x52888. The text cursor should be blinking to the left of 1D. Select 1D, and type 14. Your cursor should now be blinking to the left of 2F. Select 2F, and replace it with E0. Save your changes with Ctrl + S. You have just performed a hex tweak! Open your ROM in an emulator, and reduce samus' energy below 30. There should no longer be a low energy alarm.

PC vs SNES addresses

SNES roms are divided into banks, which are $8000 bytes long (32,768 bytes in decimal). Super Metroid is of the rom type LoROM, so it can address banks from bank $80-$FF. Because HxD uses PC addresses, and the majority of documentation for SNES games is written with SNES addresses, it's important to know the distinction between the two. PC addresses start at $000000, while SNES addresses start at $80:8000. Every SNES bank starts at $XX:8000, where XX is the bank number. The game reads addresses in this LoROM format. In a LoROM address, the bank is number separated by a colon.

Examples:

PC address SNES address
$4000 $80:C000
$9500 $81:0500
$791F8 $8F:91F8
$7FFFF $8F:FFFF

Looking at the LoROM addresses, we can see these addresses are referring to locations in banks 80, 81, 8F, and 8F (again), respectively.

It is not necessarily important to know how to convert between PC and LoROM addresses, since there is a program called Lunar Address which is highly recommended to use for this purpose; it's just important to understand the difference.

To know at a glance whether or not an address is a SNES or PC address, know that Super Metroid, as well as just about every other SNES game, never comes close to reaching $80:8000 in PC, so any address starting there or beyond is very likely a SNES address.

List of SM's Banks at a Glance

From the SMMM:

Bank $##        LoROM address          PC address        Bank description
---------------------------------------------------------------------------------------------------------------------
Bank $80      $80:0000-$80:7FFF      $0-7FFF             Game setup, intros, save station data, other important stuff.
Bank $81      $81:8000-$81:FFFF      $8000-FFFF          Map data, save data, sprite drawing routines, etc.
Bank $82      $82:0000-$82:7FFF      $10000-17FFF        Load areas, pause data, game states, HDMA, demo setup, Samus dying, room setup, etc.
Bank $83      $83:8000-$83:FFFF      $18000-1FFFF        FX Data, door data, FX 'Animated Tiles' and 'Palette Setup' setup.
Bank $84      $84:0000-$84:7FFF      $20000-27FFF        PLM setup, PLM data, probably other stuff.
Bank $85      $85:8000-$85:FFFF      $28000-2FFFF        Message boxes from PLMs and Samus's ship.
Bank $86      $86:0000-$86:7FFF      $30000-37FFF        Enemy projectiles, enemy drops setup.
Bank $87      $87:8000-$87:FFFF      $38000-3FFFF        FX graphics, golden boss statue graphics.
Bank $88      $88:0000-$88:7FFF      $40000-47FFF        DMA/HDMA stuff, power bomb explosions, Crateria scrolling sky, etc.
Bank $89      $89:8000-$89:FFFF      $48000-4FFFF        Item graphics, palette blends, FX color math stuff.
Bank $8A      $8A:0000-$8A:7FFF      $50000-57FFF        FX tilemaps, free space.
Bank $8B      $8B:8000-$8B:FFFF      $58000-5FFFF        Screen fades, OAM stuff, title setup, ending and credits stuff, etc.
Bank $8C      $8C:0000-$8C:7FFF      $60000-67FFF        Intro & menu tilemaps, ending tilemaps, etc.
Bank $8D      $8D:8000-$8D:FFFF      $68000-6FFFF        FX palettes, cheat for damage in heated rooms, etc.
Bank $8E      $8E:0000-$8E:7FFF      $70000-77FFF        Main menu palettes and graphics, etc.
Bank $8F      $8F:8000-$8F:FFFF      $78000-7FFFF        Room headers, PLM Set data, Background data, Room Scrolls data, etc.

Bank $90      $90:0000-$90:7FFF      $80000-87FFF        Samus's animations/movement/weapons, shinesparking, minimap, hitbox collision, etc.
Bank $91      $91:8000-$91:FFFF      $88000-8FFFF        Samus's movement transitions/frame delays, other Samus data, demo inputs, etc.
Bank $92      $92:0000-$92:7FFF      $90000-97FFF        Animation pointer tables, animation data, tilemaps, etc.
Bank $93      $93:8000-$93:FFFF      $98000-9FFFF        Samus's beam animation tilemaps.
Bank $94      $94:0000-$94:7FFF      $A0000-A7FFF        BTS collision, start of "Special GFX" in SMILE.
Bank $95      $95:8000-$95:FFFF      $A8000-AFFFF        "Special GFX" in SMILE.
Bank $96      $96:0000-$96:7FFF      $B0000-B7FFF        "Special GFX" in SMILE.
Bank $97      $97:8000-$97:FFFF      $B8000-BFFFF        "Special GFX" in SMILE.
Bank $98      $98:0000-$98:7FFF      $C0000-C7FFF        "Special GFX" in SMILE.
Bank $99      $99:8000-$99:FFFF      $C8000-CFFFF        "Special GFX" in SMILE.
Bank $9A      $9A:0000-$9A:7FFF      $D0000-D7FFF        Grapple graphics, layer FX graphics, beam graphics, common sprite graphics, etc.
Bank $9B      $9B:8000-$9B:FFFF      $D8000-DFFFF        Samus's graphics.
Bank $9C      $9C:0000-$9C:7FFF      $E0000-E7FFF        Samus's graphics.
Bank $9D      $9D:8000-$9D:FFFF      $E8000-EFFFF        Samus's graphics.
Bank $9E      $9E:0000-$9E:7FFF      $F0000-F7FFF        Samus's graphics.
Bank $9F      $9F:8000-$9F:FFFF      $F8000-FFFFF        Samus's graphics.

Bank $A0      $A0:0000-$A0:7FFF      $100000-107FFF      Lots of common enemy routines, enemy header data, free space.
Bank $A1      $A1:8000-$A1:FFFF      $108000-10FFFF      Enemy GFX pointer data, free space.
Bank $A2      $A2:0000-$A2:7FFF      $110000-117FFF      Enemy AI.
Bank $A3      $A3:8000-$A3:FFFF      $118000-11FFFF      Enemy AI.
Bank $A4      $A4:8000-$A4:7FFF      $120000-127FFF      Enemy AI.
Bank $A5      $A5:8000-$A5:FFFF      $128000-12FFFF      Enemy AI.
Bank $A6      $A6:8000-$A6:7FFF      $130000-137FFF      Enemy AI.
Bank $A7      $A7:8000-$A7:FFFF      $138000-13FFFF      Enemy AI.
Bank $A8      $A8:8000-$A8:7FFF      $140000-147FFF      Enemy AI.
Bank $A9      $A9:8000-$A9:FFFF      $148000-14FFFF      Enemy AI.
Bank $AA      $AA:8000-$AA:7FFF      $150000-157FFF      Enemy AI.
Bank $AB      $AB:8000-$AB:FFFF      $158000-15FFFF      Enemy AI.
Bank $AC      $AC:8000-$AC:7FFF      $160000-167FFF      Enemy graphics.
Bank $AD      $AD:8000-$AD:FFFF      $168000-16FFFF      Enemy graphics.
Bank $AE      $AE:8000-$AE:7FFF      $170000-177FFF      Enemy graphics.
Bank $AF      $AF:0000-$AF:FFFF      $178000-17FFFF      Enemy graphics.

Bank $B0      $B0:0000-$B0:7FFF      $180000-187FFF      Enemy graphics.
Bank $B1      $B1:8000-$B1:FFFF      $188000-18FFFF      Enemy graphics.
Bank $B2      $B2:0000-$B2:7FFF      $190000-197FFF      Space pirate hitboxes, also tilemaps(?), etc.
Bank $B3      $B3:8000-$B3:FFFF      $198000-19FFFF      Miscellaneous enemy/boss stuff (i.e, Botwoon's destroyed wall), etc.
Bank $B4      $B4:0000-$B4:7FFF      $1A0000-1A7FFF      Enemy Set pointer data, debug stuff, enemy instructions/weaknesses/drops.
Bank $B5      $B5:8000-$B5:FFFF      $1A8000-1AFFFF      Area map tilemaps, free space.
Bank $B6      $B6:0000-$B6:7FFF      $1B0000-1B7FFF      Graphics and tilemaps for the equipment/map/title screens.
Bank $B7      $B7:8000-$B7:FFFF      $1B8000-1BFFFF      Enemy graphics (Tourian enemies, Botwoon, etc.)
Bank $B8      $B8:0000-$B8:7FFF      $1C0000-1C7FFF      Free space (unused bank).
Bank $B9      $B9:8000-$B9:FFFF      $1C8000-1CFFFF      CRE graphics/table, Background pointer tilemaps.
Bank $BA      $BA:0000-$BA:7FFF      $1D0000-1D7FFF      Background pointer tilemaps, tileset graphics.
Bank $BB      $BB:8000-$BB:FFFF      $1D8000-1DFFFF      Tileset graphics.
Bank $BC      $BC:0000-$BC:7FFF      $1E0000-1E7FFF      Tileset graphics.
Bank $BD      $BD:8000-$BD:FFFF      $1E8000-1EFFFF      Tileset graphics.
Bank $BE      $BE:0000-$BE:7FFF      $1F0000-1F7FFF      Tileset graphics.
Bank $BF      $BF:8000-$BF:FFFF      $1F8000-1FFFFF      Tileset graphics.

Bank $C0      $C0:0000-$C0:7FFF      $200000-207FFF      Tileset graphics.
Bank $C1      $C1:8000-$C1:FFFF      $208000-20FFFF      Tileset graphics, tileset tables, etc.
Bank $C2      $C2:0000-$C2:7FFF      $210000-217FFF      Tileset tables, tileset palettes, level data.
Bank $C3      $C3:8000-$C3:FFFF      $218000-21FFFF      Level data.
Bank $C4      $C4:0000-$C4:7FFF      $220000-227FFF      Level data.
Bank $C5      $C5:8000-$C5:FFFF      $228000-22FFFF      Level data.
Bank $C6      $C6:0000-$C6:7FFF      $230000-237FFF      Level data.
Bank $C7      $C7:8000-$C7:FFFF      $238000-23FFFF      Level data.
Bank $C8      $C8:0000-$C8:7FFF      $240000-247FFF      Level data.
Bank $C9      $C9:8000-$C9:FFFF      $248000-24FFFF      Level data.
Bank $CA      $CA:0000-$CA:7FFF      $250000-257FFF      Level data.
Bank $CB      $CB:8000-$CB:FFFF      $258000-25FFFF      Level data.
Bank $CC      $CC:0000-$CC:7FFF      $260000-267FFF      Level data.
Bank $CD      $CD:8000-$CD:FFFF      $268000-26FFFF      Level data.
Bank $CE      $CE:0000-$CE:7FFF      $270000-277FFF      Level data.
Bank $CF      $CF:8000-$CF:FFFF      $278000-27FFFF      Music/audio setup.

Bank $D0      $D0:0000-$D0:7FFF      $280000-287FFF      Music data.
Bank $D1      $D1:8000-$D1:FFFF      $288000-28FFFF      Music data.
Bank $D2      $D2:0000-$D2:7FFF      $290000-297FFF      Music data.
Bank $D3      $D3:8000-$D3:FFFF      $298000-29FFFF      Music data.
Bank $D4      $D4:0000-$D4:7FFF      $2A0000-2A7FFF      Music data.
Bank $D5      $D5:8000-$D5:FFFF      $2A8000-2AFFFF      Music data.
Bank $D6      $D6:0000-$D6:7FFF      $2B0000-2B7FFF      Music data.
Bank $D7      $D7:8000-$D7:FFFF      $2B8000-2BFFFF      Music data.
Bank $D8      $D8:0000-$D8:7FFF      $2C0000-2C7FFF      Music data.
Bank $D9      $D9:8000-$D9:FFFF      $2C8000-2CFFFF      Music data.
Bank $DA      $DA:0000-$DA:7FFF      $2D0000-2D7FFF      Music data.
Bank $DB      $DB:8000-$DB:FFFF      $2D8000-2DFFFF      Music data.
Bank $DC      $DC:0000-$DC:7FFF      $2E0000-2E7FFF      Music data.
Bank $DD      $DD:8000-$DD:FFFF      $2E8000-2EFFFF      Music data.
Bank $DE      $DE:0000-$DE:7FFF      $2F0000-2F7FFF      Music data.
Bank $DF      $DF:8000-$DF:FFFF      $2F8000-2FFFFF      Unused songs, note length table, ASDR settings, tracker, etc.

Banks $E0-FF must be added by SMILE ("ROM" > "Expand ROM") before they can be seen in a hex editor.

Bank $E0      $E0:0000-$E0:7FFF      $300000-307FFF      Free space
Bank $E1      $E1:8000-$E1:FFFF      $308000-30FFFF      Free space
Bank $E2      $E2:0000-$E2:7FFF      $310000-317FFF      Free space
Bank $E3      $E3:8000-$E3:FFFF      $318000-31FFFF      Free space
Bank $E4      $E4:0000-$E4:7FFF      $320000-327FFF      Free space
Bank $E5      $E5:8000-$E5:FFFF      $328000-32FFFF      Free space
Bank $E6      $E6:0000-$E6:7FFF      $330000-337FFF      Free space
Bank $E7      $E7:8000-$E7:FFFF      $338000-33FFFF      Free space
Bank $E8      $E8:0000-$E8:7FFF      $340000-347FFF      Free space
Bank $E9      $E9:8000-$E9:FFFF      $348000-34FFFF      Free space
Bank $EA      $EA:0000-$EA:7FFF      $350000-357FFF      Free space
Bank $EB      $EB:8000-$EB:FFFF      $358000-35FFFF      Free space
Bank $EC      $EC:0000-$EC:7FFF      $360000-367FFF      Free space
Bank $ED      $ED:8000-$ED:FFFF      $368000-36FFFF      Free space
Bank $EE      $EE:0000-$EE:7FFF      $370000-377FFF      Free space
Bank $EF      $EF:8000-$EF:FFFF      $378000-37FFFF      Free space
Bank $F0      $F0:0000-$F0:7FFF      $380000-387FFF      Free space

Bank $F1      $F1:8000-$F1:FFFF      $388000-38FFFF      Free space
Bank $F2      $F2:0000-$F2:7FFF      $390000-397FFF      Free space
Bank $F3      $F3:8000-$F3:FFFF      $398000-39FFFF      Free space
Bank $F4      $F4:0000-$F4:7FFF      $3A0000-3A7FFF      Free space
Bank $F5      $F5:8000-$F5:FFFF      $3A8000-3AFFFF      Free space
Bank $F6      $F6:0000-$F6:7FFF      $3B0000-3B7FFF      Free space
Bank $F7      $F7:8000-$F7:FFFF      $3B8000-3BFFFF      Free space
Bank $F8      $F8:0000-$F8:7FFF      $3C0000-3C7FFF      Free space
Bank $F9      $F9:8000-$F9:FFFF      $3C8000-3CFFFF      Free space
Bank $FA      $FA:0000-$FA:7FFF      $3D0000-3D7FFF      Free space
Bank $FB      $FB:8000-$FB:FFFF      $3D8000-3DFFFF      Free space
Bank $FC      $FC:0000-$FC:7FFF      $3E0000-3E7FFF      Free space
Bank $FD      $FD:8000-$FD:FFFF      $3E8000-3EFFFF      Free space
Bank $FE      $FE:0000-$FE:7FFF      $3F0000-3F7FFF      Free space
Bank $FF      $FF:8000-$FF:FFFF      $3F8000-3FFFFF      Free space
general/guides/hxd_guide.txt · Last modified: 2018/06/06 09:06 by nodever2