Disk Controller

The disk controller is the circuit which enables the CPU to communicate with a hard disk, floppy disk or other kind of disk drive.

Early disk controllers were identified by their storage methods and data encoding. They were typically implemented on a separate controller card. Modified frequency modulation (MFM) controllers were the most common type in small computers, used for both floppy disk and hard disk drives. Run length limited (RLL) controllers used data compression to increase storage capacity by about 50%. Priam created a proprietary storage algorithm that could double the disk storage. Shugart Associates Systems Interface (SASI) was a predecessor to SCSI.

Modern disk controllers are integrated into the disk drive. For example, disks called "SCSI disks" have built-in SCSI controllers. In the past, before most SCSI controller functionality was implemented in a single chip, separate SCSI controllers interfaced disks to the SCSI bus.

The most common types of interfaces provided nowadays by disk controllers are PATA (IDE) and Serial ATA for home use. High-end disks use SCSI, Fibre Channel or Serial Attached SCSI.

Read more about Disk ControllerDisk Controller Versus Host Adapter

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Applix 1616 - Hardware - Disk Controller Card
... The disk controller card contains A Zilog Z80 processor running at 6 MHz 32 kibibytes of ROM 64 kibibytes of Static RAM a WD1772 floppy disk controller dual RS232 serial ports using a ...
Micromation - History
... Micromation's first major product was an S-100 bus floppy disk controller card called the "Doubler", named for its ability to record information on 8" floppy diskettes at twice the bit density ... of the Intel SBC-202 Double Density MMFM Floppy Disk Controller in 1980 ... This disk controller was the only Multibus-I product made by Micromation ...
Dick Smith Super-80 Computer - Modifications
... The Universal Floppy Disk Controller (UFDC) was an add-on floppy disk interface developed by Microcomputer Engineering (MCE) ... The UFDC was based on the Western Digital WD2793 floppy disk controller chip and had a Z80 DMA controller on board ... The most popular disk format was 5ΒΌ" (133 mm) 80 track, double sided, double density using a Mitsubishi floppy drive mechanism ...
Disk Controller Versus Host Adapter
... On the other hand, a disk controller allows a disk to talk to the same bus ... In fact signals read by a disk read-and-write head are converted by a disk controller, then transmitted over the peripheral bus, then converted again by the host ... Sometimes there may be yet another controller between a host adapter and a disk controller - a disk array controller that allows hardware RAID to be ...
Floppy Disk Controller
... A floppy disk controller (FDC) is a special-purpose chip and associated disk controller circuitry that directs and controls reading from and writing to a computer's floppy disk ... The concepts may or may not be applicable to, or illustrative of, other controllers or architectures ...

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