Apple Macintosh laptops used a squarish external SCSI connector called an HDI-30 (High Density Interconnect) on the laptop itself (not on the peripheral end of the cable, unless two laptops were being connected). These machines also had the interesting ability to become "SCSI slaves" (officially known as "SCSI Disk Mode" in Apple documentation), meaning that they could appear to be disk drives when attached to another computer's SCSI controller (a feature later reimplemented over FireWire and Thunderbolt for later, non-SCSI Mac hardware).