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The Castlevania Dungeon Forums => Fan Stuff => Topic started by: TheouAegis on June 22, 2022, 11:58:32 PM

Title: Here's how to edit NES Castlevania's hidden items
Post by: TheouAegis on June 22, 2022, 11:58:32 PM
I'm sure some of you will be happy that I was working with the US release, which I'm sure is what 99% of modders are using.

Open the US ROM and jump to address $018048. It should be 0xB6DA1A00. This is the very first hidden item in the game. Each set of items is terminated by 0xFF, so you could potentially have 8 hidden items per stage. The status of a hidden item is bitmasked in RAM address $0144. The neighboring RAM address $0145 is used to keep track of how long Simon stays in place when necessary.

Here are the pointers for each stage (excluding Hard Mode numbering). This address map can be found at 0x01FC48 in the US ROM. Add #018010 to each pointer to find its corresponding address in the ROM. A lot of these just point to terminal #FF.
8038    Stage 00
804A    Stage 01
8041    Stage 02
804F    Stage 03
83FB    Stage 04
8400    Stage 05
8409    Stage 06
8556    Stage 07
8548    Stage 08
8551    Stage 09
87A0    Stage 10
87A0    Stage 11
87A0    Stage 12
89AF    Stage 13
89B4    Stage 14
89C0    Stage 15
8AE5    Stage 16
8AE1    Stage 17
8B39    Stage 18

Item definitions are in the following bitmasked format:

Y = Y-coordinate
D = Difficulty
M = Mode
L = Level
X = X-coordinate
S = Screen (i.e., X div 256)
V = Vertical offset
H = Horizontal offset
I = Item number

Both X and Y are handled as-is (no arithmetic) and correspond to where Simon must posture. In other words, Y is always a multiple of 16 and X is a multiple of 8. Both V and H can be thought of in terms of 16*V or 16*H and refer to the position the item itself will spawn, relative to Simon.

There are 4 modes. Mode 0 requires Simon to stand still for 2 seconds. Mode 1 is just a quick duck at the spawn zone. Mode 2 requires Simon to stay in place while holding left or right for 2 seconds (this can be done while ducking, or by walking into a wall). Mode 3 just means Simon merely has to walk over the spawn area.

The Item numbers are as follows. Note that descriptions are based on Stage 04's sprites.
#00    Coins
#01    1UP
#02    Crown
#03    Chest
#04    Moai
I haven't found a way to get the shoes, coffee, kittens, or love letter. Then again, I didn't really take the time to test out all 256 possible item numbers.
Title: Re: Here's how to edit NES Castlevania's hidden items
Post by: X on June 23, 2022, 09:42:30 AM
shoes, coffee, kittens, or love letter

These I did not know about. The rest I apparently did as they were indicated on game maps.
Title: Re: Here's how to edit NES Castlevania's hidden items
Post by: TheouAegis on June 23, 2022, 04:40:03 PM
They were mentioned on The Cutting Room Floor. All of them are available in any screen that has the crown or moai sprites loaded. They were never used, and since I gave up trying to find them after 20 or so attempts, they probably wouldn't have any effect even if you could find the proper sprite definitions.

BTW I realized I left out the address for where the pointers are. I'll fix that tonight.