text: Amstrad used Hitachi's 3" floppy disc drive. Its decision to do so, when the rest of the PC industry was moving to Sony's 3.5" format, is often wrongly claimed to be due to Amstrad bulk-buying a large consignment of 3" drive units in Asia; the units were custom-made by Panasonic. The chosen drive (built-in for later models) is a single-sided 40-track unit that requires the user to physically remove and flip the disc to access the other side. Each side has its own independent write-protect switch. The sides are termed "A" and "B", with each one commonly formatted to 180 kB (in AMSDOS format, comprising 2 kB directory and 178 kB storage) for a total of 360 kB per disc.