ESDI connector ESDI=Enhanced Small Device Interface. Developed by Maxtor in the early 1980´s as an upgrade and improvement to the ST506 design.
IDE Internal connector IDE=Integrated Drive Electronics.Developed by Compaq and Western Digital. Newer version of IDE goes under the name ATA=AT bus Attachment.
SCSI Internal (Single-ended) connector SCSI=Small Computer System Interface. Based on an original design by Shugart Associates. SCSI was ratified in 1986.
ST506/412 connector Developed by Seagate. Also known as MFM or RLL since these are the encoding methods used to store data. Seagate originally developed it to support their ST506 (5 MB) and ST412 (10 MB) drives.
Serial ATA bus The Serial ATA [SATA] bus is the serial version of the IDE [ATA] spec.
Apple Macintosh
Apple ATA connector The internal hard disk has a 48-pin connector that carries both the ATA signals and the power for the drive.
Apple SCSI connector This connector is present on the Macintosh PowerBook series (except the Duo 210/230).