SH204
The first hard drive available for the Atari ST, with a capacity of 20 megabytes.
Internally, the actual drive was MFM/RLL. It hooked up to an Adaptec MFM-SASI adaptor, which was then hooked to a host adaptor card.
The Atari SH204 Host Adaptor Card
The host adaptor card used in the SH204 was primitive. It was based around SASI, an early version of SCSI that supported fewer commands and had no support for parity. As a consequence, very few SCSI hard drives made after the mid-1980s work with this card.