HD20 M0135. One of Apple’s first external hard drive developed for the Macintosh. Made for the 512K, the hard drive uses the external floppy port. It also has a port that you can plug another HD20 or your floppy drive into, so you don’t lose the use of your external disk drive. This is not a SCSI hard drive inside or out.
The Hard Disk 20 holds a whopping 20MB of data which is over 50 times the space of a 400K 3.5″ disk. It also introduced us to the Hierarchical File System (HFS). Start up from a floppy disk is required for the 512K, but with the 128K ROM, the 512Ke and Plus can boot directly from it.
This is a non working drive. The drive makes noises but does not spin up. As it is pre SCSI and uses a proprietary Rodime drive, it is not fixable by us. Sold as-is.