PC-Hardware: IDE and SCSI

• IDE (Integrated Device Electronics) Bus: For hard disks, Floppy drives and CD-ROM (ATAPI standard) or DVD drives. IDE has its own PCI card internal to the motherboard: Two IDE connectors (I/O ports 0xF000-0xF007 and 0xF008-0xF00F, and IRQ 14 and 15).
  Two IDE hard drives can be connected to a single IDE ribbon: Master (MA), Slave (SL), Cable Select (CS).
  
  
• SCSI (Small Computer Standard Interface): For disk or tape drives, CD-ROMs, or other devices (chained). Needs SCSI host adaptor or SCSI card (may be on motherboard).