The IBM 3830 Storage Control Unit, a contemporaneous and quite similar controller, uses its internal processor to control a 23FD.

The first floppy disk drive controller (FDC) like the first floppy disk drive (the IBM 23FD) shipped in 1971 as a component in the IBM 2385 Storage Control Unit for the IBM 2305 fixed head disk drive, and of the System 370 Models 155 and 165. In more modern systems, the FDC, if present at all, is typically part of the many functions provided by a single super I/O chip. In these systems, the controller also often combined a microcontroller to handle data transfer over standardized connectors like SCSI and IDE that could be used with any computer. Later designs included more of this functionality on the controller and reduced the complexity of the external circuitry single-chip solutions were common by the later 1980s.īy the 1990s, the floppy disk was increasingly giving way to hard drives, which required similar controllers. Early controllers required additional circuitry to perform specific tasks like providing clock signals and setting various options. The FDC is responsible for reading data presented from the host computer and converting it to the drive's on-disk format using one of a number of encoding schemes, like FM encoding (single density) or MFM encoding (double density), and reading those formats and returning it to its original binary values.ĭepending on the platform, data transfers between the controller and host computer would be controlled by the computer's own microprocessor, or an inexpensive dedicated microprocessor like the MOS 6507 or Zilog Z80. An FDC directs and controls reading from and writing to a computer's floppy disk drive (FDD). The NEC D765AC FDC IC is the large dual in-line package at the top.Ī floppy-disk controller ( FDC) has evolved from a discrete set of components on one or more circuit boards to a special-purpose integrated circuit (IC or 'chip') or a component thereof. For the logic, see 3-state.įDC board from an IBM 5150.

What format is floppy disk