EmulatorII-list

I was wondering - if I get an old mac that doesn't have a cd-drive, 
does it need 2 scsi ports?  1 for the cd-drive and one going to the 
EII?  I've never used these old machines before (or anything with 
scsi).  Could some of you list your set-ups so I can get an idea of 
what I need?  Thanks again for your help,
Martin