0
For the PC version of Final Fantasy 4 the inventory appears to be in a 4 byte pattern as follows
Item ID / Checksum or Type / Amount / Spacer or overflow
For example one potion would exactly be like this: 89 13 01 00
89 is the ID for a Potion
13 appears to be associated to most consumable items
01 is how many potions you have
00 is typically seen between this item and the next changing it is inadvisable.
Typically those interested in guides such as this are already familiar with Hex editing so this part can be comfortably skipped for those who are already familiar with it.
Ok so now for complicated stuff. Computers allocate and store information in Random Access Memory, also known as RAM. This space is allocated in virtual mailboxes. Typically these mailboxes are addressed Byte by Byte each capable of storing a value between 0 and 255. If greater values are required these Mailboxes are combined and value capacity is increased exponentially. Anyway computers haven't changed much since they were invented and still can only count in binary. Bits are too small to do anything substantial with so we combine four bits at a time and we can now count instead of just 0 and 1, but from 0 to 16. Since memory and values are typically represented as pairs of Hexs and its much easier to look at two characters instead of a bunch of decimal numbers, we developed the Hexidecimal system, where a single place value counts up beyond 10 to 15. an example:
1,2,3,4,5,6,7,8,9,A,B,C,D,E,F
The that example the letter A represents 10, B: 11, C: 12 and so on. since 0 is considered a number, that adds up to a total of 16 values.
Any further clarification or questions please address them in the comments and i will be happy to modify this section.
Inventory Location
The FInal Fantasy 4 Inventory appears to start at the following address: 00632c00
Somewhere else there is a value describing how many inventory items you have, I have not found it yet however.
With that said, you gotta have something to change it into something else. Potions are relatively cheap so you can easily start there.
In the following sections ill be listing Items by their ID and Type/Checksum
The values i have found so far have been found using trial and error. Any values the game didn't like Crashed it immediately.
Consumable Items
Potion: 89 13
Hi-Potion: 8A 13
X-Potion: 8B 13
Ether: 8C 13
Dry Ether: 8D 13
Elixir: 8E 13
Megalixir: 8F 13
Phoenix Down: 90 13
Gold Needle: 91 13
Echo Herbs: 95 13
Eye Drops: 96 13
Antidote: 97 13
Unicorn Horn: 9B 13
Tent: 9c 13
Cottage: 9D 13
Emergency Exit: 9E 13
Gnomish Bread: 9F 13
Gysahl Greens: A0 13
Gysahl Whistle: A1 13
Gold Apple: A2 13
Silver Apple: A3 13
Soma Drop: A4 13
Siren: A5 13
Lustful Lali-Ho: A6 13
Ninja Sutra: A7 13
Red Fang: AB 13
White Fang: AC 13
Blue Fang: AD 13
Bomb Fragment: AE 13
Bomb Crank: AF 13
Antarctic Wind: B0 13
Arctic Wind: B1 13
Zeus's Wrath: B2 13
Heavenly Wrath: B3 13
Gaia's Wrath: B4 13
Bomb Core: B5 13
StarDust: B6 13
Lilith's Kiss: B7 13
Vampire Kiss: B8 13
Spider Silk: B9 13
Silent Bell: BA 13
Coeurl Whisker: BB 13
Beastiary: BC 13
Bronze Hourglass: BD 13
Silver Hourglass: BE 13
Gold Hourglass: BF 13
Bacchus's Wine: C0 13
Hermes Sandals: C1 13
Decoy: C2 13
Light Curtain: C3 13
Lunar Curtain: C4 13
Crystal: C5 13
Member's Writ: C6 13
Pink tail: 32 23
Swords
Dark Sword: 71 17
ShadowBlade: 72 17
Deathbringer: 73 17
Mythgraven Sword: 74 17
Lustrous Sword: 75 17
Excalibur: 76 17
Ragnarok: 77 17
Ancient Sword: 78 17
Blood Sword: 79 17
Mythril Sword: 7A 17
Sleep Blade: 7B 17
Flame Sword: 7C 17
Icebrand: 7D 17
Stone Blade: 7E 17
Avenger: 7F 17
Defender: 80 17
Fireshard: 81 17
Claws
Flame Claw: 01 19
Ice Claw: 02 19
Lightning Claw: 03 19
Faerie Claw: 04 19
Hell Claw: 05 19
Cat Claw: 06 19
Rods
Rod: 91 1A
Flame Rod: 92 1A
Ice Rod: 93 1A
Thunder Rod: 94 1A
Lilith Rod: 95 1A
Polymorph Rod: 96 1A
Faerie Rod: 97 1A
Stardust Rod: 98 1A
Staves
Staff: F5 1A
Healing Staff: F6 1A
Mythril Staff: F7 1A
Power Staff: F8 1A
Aura Staff: F9 1A
Sage's Staff: FA 1A
Rune Staff: FB 1A
Helms:
Leather cap: A5 1f
Dark Helm: AB 1F
Hades Helm: AC 1f
Sage's Miter: AD 1f
Black Cowl: AE 1f
Demon Helm: AF 1f
Armor:
Clothing: 09 20
Prison Garb: 0A 20
Leather Clothing: 0B 20
Bard's Tunic: 0C 20
Gaia Gear: 0D 20
Iron Armor: 0E 20
Dark Armor: 0F 20
Sage's Surplice: 10 20
Kenpo Gi: 11 20
Hades Armor: 12 20
Black Robe: 13 20
Demon Armor: 14 20
Black Belt Gi: 15 20
Adamant Armor: 23 20
Shields:
Dark Shield: 42 1f
Demon Shield: 43 1f
Lustrous Shield: 44 1f
Mythril Shield: 45 1f
Flame Shield: 46 1f
Gloves:
Dark Gloves: 70 20
Iron Armlet: 71 20
Power Armlet: 72 20
Hades Gloves: 73 20
Demon Gloves: 74 20
Silver Armlet: 75 20
Gauntlets: 76 20
Bows:
Bow: 59 1B
Arrows
Medusa Arrows: BD 1B
Iron Arrows: BE 1B
Holy Arrows: BF 1B
Fire Arrows: C0 1B
Ice Arrows: C1 1B
Summons
Goblin: 8C 23
Bomb: 8D 23
Cocktrice: 8E 23
Mindflayer: 8F 23
Troubleshooting
A user posted a question in the comments which inspired this section. I felt that future readers will likely find this helpful when using this guide.
These things can be rather complicated and a lot of times when something should work it doesnt. On the flip side sometimes when something shouldnt work, it does and makes me question the fabric of reality but thats for another time and guide.
By no means is this guide a defacto solution to hacking and modifying in game memory. I admit this is a very crude method but it works for me and could be a valuable stepping stone for those intrested in learning more about how to manipulate data.
Step one is i highly suggest using cheat engine to do the method described below. Open the game then open Cheat engine and attach it to the final fantasy 4 process (not the launcher if you still have that open)
Next head into a shop within the game, and look at your amount of potions. For some reason the game willl not actually pull info from a save until its actually requested so you litterally have to open your inventory and view it for the information to even be stored in memory registers. search for the number of potions you have, also its better if you have greater than 0. the inventory system is very complex for my level of skill so once you have that number search for it. Then purchase one potion and search for that that number within your results for the change. Continue until you have exactly one result, and that is where your potions are stored (the amount anyway)
If you are using cheat engine you should be able to add that address to your list and once you do that you can right click it and "Browse this memory region". There you will see values and numbers you can plug in with the values found here in this guide.
Some search methods may return many results. Here is the thing when doing the search, The value for the amount of potions, for this game anyway will never be greater than 1 byte in length so if you are searching for a value type that is 4 bytes, it is likely that you will end up with 0 results. You could likely get away with 2 bytes value type since the value for amount is stored right after the ID and checksum. the value following the amount of items is always 00 so when you search for 8 potions for example a value type of 1 one byte will look for eveything that looks like 08 where as a 2 byte will look for 0008.
Source