Philippe, 

I can't tell you precisely what kind of interface it is...but I know that 
you can hook up a hard drive. A Google search of "Dreamcast hard drive" 
turns up some good stuff, including this HOWTO of hooking up a hard disk: 

http://mini-itx.com/projects/dreamcastpc/ 

Hope that's helpful. 

Alex Kirk 

> Hi, I'd like to know what is exactly the type of interface that connects the
> GD-Rom drive to the Dreamcast's motherboard. 
> 
> http://mail-index.netbsd.org/port-dreamcast/2001/01/21/0004.html 
> 
> According to this link, it's some kind of scsi device ? would it be possible
> to use another scsi device .. I.E. a harddrive ? If you could just lighten
> me up a bit i'd be happy =). 
> 
> Thanks,
> Philippe