The Apple Hard Disk 20 was Apple’s first hard disk drive for the Macintosh, introduced in 1985. With a capacity of 20 MB, it was a major upgrade at a time when most Macintosh systems relied solely on floppy disks. Functionality & Compatibility: Designed for early Macintosh models, including the Macintosh 128K, 512K and 512Ke Connects via Apple’s proprietary HDI-20 / floppy port, not SCSI Allowed users to: Store applications and documents permanently Boot Mac OS directly from the hard disk Significantly reduce floppy disk usage Improve workflow speed compared to floppy only systems The Hard Disk 20 was an important step in making the Macintosh a more practical machine for business and professional use. Condition: Sold as untested / as-is Cosmetic condition consistent with age A historically significant and increasingly scarce accessory, ideal for Apple collectors, restoration projects, or display in a vintage Macintosh setup.