The entire title screen isn't written in the format you discovered - only everything besides the Akumajou Densetsu logo itself is written that way. The logo is just written straight out, no formatting at all.
Hrmph... I find that a little difficult to swallow. Why would the game have a duplicate drawing routine to draw something it's already drawing in another routine? Not that I doubt you -- I mean I've seen crazier things in games -- I'm just a little perplexed.
Are you sure the logo isn't inside a 80-FE style block? What offset did you find it at?
I'll take another look at this in a bit.
it would be impossible to insert the logo through a hex editor.
As long as your logo does not exceed the limits of the NES's capabilities, then it is possible. We just haven't figured out how to do it yet. ;P
Oh, and Disch, where did you learn NES assembly? I know it's 6502, but I can't find any good resources for learning it as well as how to apply it when ROM hacking.
A long long time ago, in a previous life, I read 6502.txt, nestech.txt, then wrote an emulator to exercise that info.
These days, 6502.txt is still pretty solid to learn the basics, as it does a great job of giving you a high-level, reasonably easy to understand overview. Though for a quick reference of opcodes and stuff, Obelisk is better:http://www.obelisk.demon.co.uk/6502/reference.html
( EDIT: I just looked at 6502.txt again and it isn't as great as I remember. Was I thinking of another doc? Whatever, it was over a decade ago -- I can't remember =x )
nestech.txt is extremely
outdated these days, and I would not recommend it. Probably the most complete source of info is the nesdev wiki, although I don't know how "beginner friendly" it is, as it seems to be oriented more towards emu developers than hackers -- but maybe that's just the parts of it that I go to. There's also a "Programming Guide" page on it that illustrates things from a homebrewer standpoint -- though I don't know if that'd be any easier for a hacker:http://wiki.nesdev.com/w/index.php/Nesdev_Wiki
As for "how to apply it to ROM hacking" -- my advice is don't worry about that, and focus on the knowledge itself. Once you understand the big picture, how to apply it will be obvious/self-evident.
Alternatively, you could read some kind of "learn to hack NES assembly in 6 steps" guide that loosely shows how to apply the knowledge without really explaining the knowledge itself -- but I don't like to learn things that way. I'm sure there are guides like this out there (maybe even on this site?) but I don't know of any and probably wouldn't recommend them anyway.
More than once I've considered making a "learn NES assembly for ROM hacking" guide. Maybe one of these days I'll do that.
I just double checked and it certainly does
look like the Akumajou Densetsu logo is stored with the rest of the title screen data as I originally thought.
The entirety of the data for the title screen starts at offset 0x0B550 and continues until the termination 'FF' character at offset 0x0B6FB.