Macintosh 400K External Drive

Background

The original Macintosh External Disk Drive (M0130) was introduced with the Macintosh on January 24, 1984. However, it did not actually ship until May 4, 1984. The drive case was designed to match the Macintosh and included the same 400-kilobyte drive (a Sony-made 3+1⁄2-inch single-sided mechanism) installed inside the Macintosh. The Macintosh could only support one external drive, limiting the number of floppy disks mounted at once to two, but both Apple and third party manufacturers developed external hard drives that connected to the Mac's floppy disk port, which had pass-through ports to accommodate daisy-chaining the external disk drive. Apple's Hard Disk 20 could accommodate an additional daisy-chained hard drive as well as an external floppy disk. The external 400-kilobyte Macintosh drive will work on any Macintosh that does not have a high density SuperDrive controller (due to electrical changes with the interface), but the disks in practice only support the MFS file system. Although a 400-kilobyte disk may be formatted with HFS, it cannot be booted from, nor is it readable in a Mac 128 or 512.