Wow, that was fast, how did you do that ? Had you already done this cheat before seeing this thread ??
Well, it works! Great job! I guess until the button sequence is discovered, you can't play with this on real NEC hardware though, that is unless there is no way by design...
I have never seen this "Developer's Room" and I don't really know much other info, but here's what this says:
Sound Test: Go to the Sound Room that is in the Developers Room. Move Adol one step from the wall to the right of the piano. Then, facing the wall, use a Black Potion. When the explosion settles, a burnt up guy will appear, and if you talk to him, you can use the Sound Test.
Awesome, and now we know the Easter egg to make the Music Supervisor appear in the Sound Room!!!!!! Yay! More if not all Ys IV cheats/eggs are now known! That's the only way to play PSG audio looks like cause the Debug Mode menu only deals in ADPCM and CDDA.
So, while investigating the Ys IV Debug Mode, I looked at the Ys IV Staff/Dev Room text block and I found these lines from the Music Supervisor:
http://vgmdb.net/forums/showpost.php?p=67252&postcount=5[06100506]
[12]You surprised<\n>
me! How cruel!
<\0><\0>
[04130506]
[12]I'm Takimoto, the<\n>
music supervisor.
<\0><\0>
[04140506]
[12]Wanna listen to my<\n>
wonderful sounds?
<\0><\0>
[080C030A]
[0C]<arrow>PSG MUSIC<\n>
<arrow>CD AUDIO<\n>
<arrow>EFFECT 1<\n>
<arrow>EFFECT 2
<\0><eos>
So I used an old save file I kept around to get me to the Ys IV Staff Room, went to the Sound Room, but Takimoto was nowhere to be found! I started to suspect there might be a trick to find him, just like you have to use the transform magic to talk to that goat to be warped to the start of the game with the special exp/gold doubling items. I tried the Mask in the room, but got nothing. After all, you could always talk to one of the staff that lets you view all portraits, cut scenes, etc. but nothing for sound, yet this text shows a menu for PSG, CD and sound effects, etc. so there had to be a way to find Takimoto - looks like David found it!
Update:
OK, I'm able to do it (he's in black'n'white after appearing), but not consistently and you don't have to explode the Black Potion. I haven't figured out exactly what causes his appearance, sometimes it takes quite a while to make him unhide. I'm still working on what exactly is the trick here.
Thanks everyone, awesome stuff! And Sam, you should do the Staff Room trick, it's one of the things that makes Ys IV and Hudson so special. You basically get to talk to all the developers via Ys characters, they tell your their job, some jokes, etc. It was a rare touch you don't see much in games! I can't recall if I ever saw another game that had this, unless you count separate bonus discs or something that deal with behind-the-scenes.
FYI: Ys IV Staff/Developers Room Code:
(
http://www.ysutopia.net/special/nec-cheats.html )
After you have finished the game, restart the program and
select Continue, then press II and the third option in the
menu will be the Ys IV Staff/Developers Room.
So you gotta beat the game at least once.