understanding dummy files

[intro]

hey folks,

i'm a sega fan from the days of old and just got into this scene which actually has me excited about playing video games again. today's platforms just don't do it for me.

my question is this: i've downloaded a bunch of games and emulators already and i'm a bit confused about the dummy files. i got a dummy creator and everything but it seems that most of the files i've downloaded have been self booting and some have even contained a dummy.dat file which i'm assuming is the dummy file. i haven't really needed to create any dummy files. i am burning on 700mb cdr's.

yesterday i was playing nester se and i was scrolling through the games rather tediously to get to tetris. when i got to the "e" games all of a sudden the screen went black and then the dreamcast started giving me problems reading games after that. i followed an online tutorial to adjust the laser and now it seems to work again but i am hesitant about playing nester se again.

should i assume that a program like nester se has a dummy file on it? is the only way to know for sure if it's there is by the file size? is a 600mb file going to read ok or does it really need that remaining 100mb filled up.

thanks in advance.

[az_bont]

The Dreamcast employs a Constant Angular Velocity (CAV) read mechanism in its drive. The disc will spin at the same speed regardless of the position of the laser. As it moves from the centre of the disc to the outer edge, it is reading more data per revolution, and so you see improved loading times. Therefore, the closer you move the data to the outer edge, the quicker it can be read by the console. This is what a dummy file achieves--it is deliberately placed at the start of the disc (the centre), usually by giving it a name beginning with one or more 0s, so as to push the useful data closer to the edge.

It has long been said that dummy files can reduce the potential for harm when using CD-Rs, but that is mostly restricted to backups/warez of commercial games, which often lacked dummy files and sometimes placed the files in an illogical order on the disc, resulting in a lot of unnecessary seeking back and forth between the disc, placing additional strain on the laser.

However, the files to be read by NesterDC, as with most emulators, are relatively small. I imagine most elements are loaded into RAM on the first boot, and then each ROM as required, each of which are so small they should only take a second or two anyway.

If I was in the habit of regularly making backups of commercial games, I would definitely make use of as large a dummy file as the disc could contain. For homebrew, however, I tend not to bother. There's certainly nothing stopping you, though, and I know of others who always dummy regardless of the disc's content. It will never be of detriment to the console, and the only downside is longer burn times.

Either way, I don't think it would be possible to create a disc with such a bad data structure that it could ruin a Dreamcast in a single play--the only affects would be accelerated wear and tear. We've seen reports of consoles giving up the ghost for years on this site, which is hardly surprising given how old the console is now, and there was going to be a disc in there when it happened--it just so happened that in this case, it was NesterDC.

As it is one of the most popular emulators for the console, I'm sure we would have seen quite an outpouring of posts from affected users if it had the potential to behave in this way. I do hope this experience hasn't sullied your opinion of the Dreamcast homebrew scene. Oh, and welcome to the site.

[mankrip]

yesterday i was playing nester se and i was scrolling through the games rather tediously to get to tetris. when i got to the "e" games all of a sudden the screen went black and then the dreamcast started giving me problems reading games after that. i followed an online tutorial to adjust the laser and now it seems to work again but i am hesitant about playing nester se again.

Sorry to hear that. Take a look at this post.

[az_bont]

yesterday i was playing nester se and i was scrolling through the games rather tediously to get to tetris. when i got to the "e" games all of a sudden the screen went black and then the dreamcast started giving me problems reading games after that. i followed an online tutorial to adjust the laser and now it seems to work again but i am hesitant about playing nester se again.

Sorry to hear that. Take a look at this post.

Perhaps even more pertinent is the post a few up from that states that NesterDC SE has been responsible for three Dreamcast lasers misaligning themselves.

Oops.

This is somewhat related to what I mentioned in my earlier post about poorly-made backups/warez, and rather uniquely applicable to this particular version of NesterDC, which is programmed to display images of cartridges and screenshots for games in the menu. Unfortunately, the file structure required means that by default, ISO creation software will place the folder full of cartridge images in a block together, separate from the folder containing screenshots and the folder containing the ROMs. It must therefore seek back and forth across the disc every time you change the selected game, causing the problems noticed by yourself and others in that thread.

There is mention made in that thread of sorting the files so that they are more logically placed on the disc, but for a disc of approximately 600MB, it would be near impossible to do without some sort of automated tool to assist you. It would be much easier to just go back to an earlier version of NesterDC that doesn't attempt to load any pictures from the disc--or perhaps just not including the images might cause the emulator attempt to read any. I'd best not recommend a version myself, as the last version I used was several major revisions ago, and I don't want to risk putting my foot in it again.

[mankrip]

I never used NesterDC SE, but I guess I'll select the few ROMs I'd really like to play and make a dummied NesterDC SE disc to see how it is.

[Christuserloeser]

It looks (and plays) fantastic. However, with the problems mentioned I do recommend v6.0 as it's the most compatible pre-SE version.

- If someone could update v7.1 (which has a nice GUI too) with the emulation core of SE than that would be a pretty damn good NES emulator.

As for SE, I think the best thing to do is to just include title screens only to keep the laser wear as low as possible. That however doesn't change the fact that it won't allow you to play hacks and translations.

Edit: Another problem with SE is that the CD Builder application doesn't work on Vista / XP64, so you'll have to burn it with BootDreams if you're using one of these OS.