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8-inch floppy disk, inserted in drive, (3½-inch floppy diskette, in front, shown for scale) 3½-inch, high-density floppy diskettes with adhesive labels affixed The first commercial floppy disks, developed in the late 1960s, were 8 inches (203.2 mm) in diameter; [4] [5] they became commercially available in 1971 as a component of IBM products and both drives and disks were then sold ...
Modified frequency modulation (MFM) is a run-length limited (RLL) line code [1] used to encode data on most floppy disks and some hard disk drives.It was first introduced on hard disks in 1970 with the IBM 3330 and then in floppy disk drives beginning with the IBM 53FD in 1976.
When the controller and disk drive are assembled as one device, as it is the case with some external floppy disk drives, e.g., Commodore 1540 and USB floppy disk drives, [27] the internal floppy disk drive and its interface are unchanged, while the assembled device presents a different interface such as IEEE-488, parallel port or USB.
Frequency modulation encoding, or simply FM, is a method of storing data that saw widespread use in early floppy disk drives and hard disk drives. The data is modified using differential Manchester encoding when written to allow clock recovery to address timing effects known as "jitter" seen on disk media.
The Commodore 1571 is Commodore's high-end 5¼" floppy disk drive, announced in the summer of 1985. With its double-sided drive mechanism, it has the ability to use double-sided, double-density (DS/DD) floppy disks, storing a total of 360 kB per floppy. It also implemented a "burst mode" that improved transfer speeds, helping address the very ...
Internal SuperDrive floppy drive on a Macintosh LC II. The term was first used by Apple Computer in 1988 to refer to their 1.44 MB 3.5 inch floppy drive.This replaced the older 800 KB floppy drive that had been standard in the Macintosh up to then, but remained compatible [citation needed] in that it could continue to read and write both 800 KB (double-sided) and 400 KB (single-sided) floppy ...
drive: 1, diskette: 2 16 8 512 2× 64 kB 270 GCR (4/5) Internally based on FDU-250 Micro Floppy Disk Drive Unit [2] Thomson: 5 1 ⁄ 4 inch Single 1 40 16 128 80 kB 300 FM Thomson UD90.070 Double 2 256 320 kB MFM Thomson DD90-320 [NB 17] 3 1 ⁄ 2 inch Double 1 80 16 256 320 kB 300 MFM Thomson TO9, Thomson DD09-350 Double 2 640 kB
Floppy drives utilize 300-oersted write heads, FM encoding, and a track width of 0.330 mm (0.0130 in) for a density of 48 tracks-per-inch (tpi) and 5,876 bits-per-inch (bpi). Double density (DD or 2D) doubles capacity over SD by replacing FM encoding with an improved line code , such as modified frequency modulation (MFM), modified modified ...