Parallel ATA (PATA), originally ATA, is an interface standard for the connection of storage devices such as hard disks, solid-state drives, floppy drives, and CD-ROM drives in computers. ...
http://en.wikipedia.org/wiki/Parallel_ATAAn 8-bit IDE interface
Although there are now technically simpler storage options for hobby projects, the 40 pin ATA IDE interface is still a ubiquitous, well documented connector which allows hard drives and Compact Flash cards (via a simple adapter) to be used. The only real complication is that ATA IDE has a 16 bit data bus, so an interface must be made in order to connect devices to 8 bit systems.
http://www.retroleum.co.uk/electronics-articles/an-8-bit-ide-interface/
