The boil was a device which attached to the side expansion slot of the A1000/A500/+ and provided an interface for attaching external hard disk boxes and was driven by the boil software. The external hard disk units were attached via a 19pin cable and were the same external hard disk units often used with the Atari ST. The boil system seems to support a variety of hard disk types including ST415/506, SCSI and AT. BOIL apparently stands for Bootable Omti Interface Loader. Some examples of the available hard disk units are the CHA-40Q and the Omti 5520 and 5528.