Romhacking.net

Romhacking => ROM Hacking Discussion => Topic started by: gzip on April 18, 2020, 03:54:05 pm

Title: Zelda 1 overworld secret path
Post by: gzip on April 18, 2020, 03:54:05 pm
You know the one, from the green gambling tree to the secret 100 rupees (or blue ring in quest 2). Zelda Tech screen 11 to 14.

First how does it work? Second, how can I move the secret path to a different location? I tried debugging around LDA $EB/$EC (A5 EB) and CMP #$1F (C9 1F) but couldn't make out anything relevant.

Btw, I have a few other questions like this around Zelda 1. Is it ok to post a new thread here under Discussion for each question or is it better to start a new thread under Personal Projects and lump them all together there? :police:
Title: Re: Zelda 1 overworld secret path
Post by: Jigglysaint on April 19, 2020, 09:37:31 pm
The data you are looking for is at 1EEA7 in the rom.  It starts with code that checks to see if you are on screen 1F, which is the screen with the secret passage.  After that it checks to see where on the screen you are.  If the game detects you are on the correct location, it will then branch to code that makes the affected area walkable as long as you are in that area on screen.
Title: Re: Zelda 1 overworld secret path
Post by: gzip on April 21, 2020, 02:26:45 am
So I was looking in the right place but I wasn't seeing it. I also missed that this is called out in Trax's bank 7 dump. ::) Anyway, thanks for pointing me in the right direction. It's very easy to change once you know where to look. Here are the relevant bytes:

Code: [Select]
1EEAA Secret passage screen number (default 1F)
1EEB6 Secret passage x position (default 70)
1EEBC Secret passage y position (default 56)