| Revision as of 14:17, 25 November 2011 editWtshymanski (talk | contribs)Extended confirmed users76,122 edits redundant; if it's plug-compatible it's got to have the same pinout as a real floppy disk drive← Previous edit | Revision as of 05:54, 26 November 2011 edit undoRwessel (talk | contribs)Extended confirmed users, Pending changes reviewers7,332 edits major copyedit. Remove/generalize excessively implementation specific details, make more encylopedic, etc.Next edit → | ||
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| ] data exchange port.]] | ] data exchange port.]] | ||
| A '''floppy disk hardware emulator''' is a device that emulates a mechanical ] drive with a ] ] ] with the drive it replaces, similar to how ]s replace mechanical ]s. | A '''floppy disk hardware emulator''' is a device that emulates a mechanical ] drive with a ] or network ] ] with the drive it replaces, similar to how ]s replace mechanical ]s. | ||
| == History == | == History == | ||
| Older models of ]s, ] and ] |
Older models of ]s, ] and ] often used floppy disk drives for data transfer. Older equipment may be difficult to replace or upgrade because of cost, requirement for continuous availability or unavailable upgrades. Proper operation may require ], software and data to be read and written from and to floppies, forcing users maintain floppy drives on supporting systems.<ref></ref> | ||
| Floppy disks and floppy drives are gradually going out of production<ref></ref><ref></ref> |
Floppy disks and floppy drives are gradually going out of production<ref>,</ref><ref></ref><ref></ref><ref></ref><ref></ref> and replacement of malfunctioning drives, and the systems hosting them, is becoming increasingly difficult. Floppy disks themselves are fragile, of may need to be replaced often. An alternative is to use a floppy disk hardware emulator, a device which appears to be a standard floppy drive to the old equipment by interfacing directly to the ], while storing data in another medium such as a ], ], or a ] on a computer network. Emulators can also be used as a higher-performance replacement for mechanical floppy disk drives. | ||
| Another kind of emulator is designed for ]<ref></ref> and ]<ref></ref><ref></ref>. These devices may be standalone or consist of a special cable and/or interface board that allow a standard PC to emulate the obsolete drive. | |||
| == Universal emulation == | == Universal emulation == | ||
| Floppy disk controller interfaces differ in their electrical interfaces. Emulators, unlike real drives, can be designed to connect to a number of different interfaces. | |||
| == Emulation process == | == Emulation process == | ||
| A typical floppy disk controller sends an ] / ] / ] encoded signal to the drive to write data, and expects a similar signal returned when reading the drive.<ref></ref> On a write, a hardware ] or a software-based filter component undoes the encoding, and stores the sector data as logically written by the host. An inverse mechanism translates the stored data back into an encoded signal when the data is read. Noisy raw data signals are filtered and cleaned up before conversion. | |||
| Most FDC interfaces do not directly address tracks, rather provide "step-in" and "step-out" pulses. Those, and the current sector number virtually rotating under the emulated read/write head, are tracked by the emulator in order to determine which sector is to be accessed.<ref></ref><ref></ref> | |||
| Because the interface to the floppy drive is very low-level, emulators must maintain the approximate timing of floppy disk operations. This may require the emulator to provide buffering, with some delay in updating the permanent storage. | |||
| * Saves the current modified track to a permanent storage or sends it to a remote storage | |||
| * Changes the current track number according to the ''Step Direction'' | |||
| * Loads the new track from local or remote storage | |||
| The emulator saves the data written to the floppy in either local storage (stand-alone emulators), or in a remote storage device or data exchange module (stateless emulators). | |||
| Stateless emulators, not equipped with an internal permanent storage, directly send data to a remote storage or to the data exchange module. Stand-alone emulators, equipped with internal memory, read and save data from and to the internal permanent storage with no need of a remote link or an external memory device always plugged in. Both stateless and stand-alone emulators, however, are required to perform all the step-pulse-related tasks within the standard floppy seek-time: less than 12ms. Slower step-pulse emulated times are very likely to cause rejection of the emulator, marked by the host as non-working or defective. | |||
| == Data exchange == | == Data exchange == | ||
| The floppy disk emulator can provide other systems access to the data on the emulated floppy in a number of ways: | |||
| Data exchange from and to a user memory device—easily extended to support multi-floppy emulation—can be implemented as: | |||
| * Direct access to some dedicated ] (e.g.: a 1.44Mb partition on a USB key) | * Direct access to some dedicated ] (e.g.: a 1.44Mb partition on a USB key) | ||
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| ''Direct access'' and ''ISO image'' implementations can also emulate system / non-standard floppies, whose file system can't be simply translated. | ''Direct access'' and ''ISO image'' implementations can also emulate system / non-standard floppies, whose file system can't be simply translated. | ||
| ''ISO image'' implementation can also be coupled with a ] to seamlessly emulate floppy drives on a |
''ISO image'' implementation can also be coupled with a ] to seamlessly emulate floppy drives on a computer. | ||
| Some devices can store multiple floppy images, and provide a mechanism to select which emulated floppy is mounted on the emulated drive. | |||
| == References == | == References == | ||
Revision as of 05:54, 26 November 2011
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A floppy disk hardware emulator is a device that emulates a mechanical floppy disk drive with a solid state or network storage device plug compatible with the drive it replaces, similar to how solid-state drives replace mechanical hard disk drives.
History
Older models of computers, electronic keyboards and industrial automation often used floppy disk drives for data transfer. Older equipment may be difficult to replace or upgrade because of cost, requirement for continuous availability or unavailable upgrades. Proper operation may require operating system, software and data to be read and written from and to floppies, forcing users maintain floppy drives on supporting systems.
Floppy disks and floppy drives are gradually going out of production and replacement of malfunctioning drives, and the systems hosting them, is becoming increasingly difficult. Floppy disks themselves are fragile, of may need to be replaced often. An alternative is to use a floppy disk hardware emulator, a device which appears to be a standard floppy drive to the old equipment by interfacing directly to the floppy disk controller, while storing data in another medium such as a USB thumb drive, Secure Digital card, or a shared drive on a computer network. Emulators can also be used as a higher-performance replacement for mechanical floppy disk drives.
Universal emulation
Floppy disk controller interfaces differ in their electrical interfaces. Emulators, unlike real drives, can be designed to connect to a number of different interfaces.
Emulation process
A typical floppy disk controller sends an MFM / FM / GCR encoded signal to the drive to write data, and expects a similar signal returned when reading the drive. On a write, a hardware PLL or a software-based filter component undoes the encoding, and stores the sector data as logically written by the host. An inverse mechanism translates the stored data back into an encoded signal when the data is read. Noisy raw data signals are filtered and cleaned up before conversion.
Most FDC interfaces do not directly address tracks, rather provide "step-in" and "step-out" pulses. Those, and the current sector number virtually rotating under the emulated read/write head, are tracked by the emulator in order to determine which sector is to be accessed.
Because the interface to the floppy drive is very low-level, emulators must maintain the approximate timing of floppy disk operations. This may require the emulator to provide buffering, with some delay in updating the permanent storage.
The emulator saves the data written to the floppy in either local storage (stand-alone emulators), or in a remote storage device or data exchange module (stateless emulators).
Data exchange
The floppy disk emulator can provide other systems access to the data on the emulated floppy in a number of ways:
- Direct access to some dedicated disk partitioning (e.g.: a 1.44Mb partition on a USB key)
- Floppy file system translation (e.g.: FAT12 floppy ↔ USB key folder)
- ISO floppy disk images (e.g.: raw floppy ↔ .iso USB key file)
Direct access and ISO image implementations can also emulate system / non-standard floppies, whose file system can't be simply translated.
ISO image implementation can also be coupled with a virtual drive to seamlessly emulate floppy drives on a computer.
Some devices can store multiple floppy images, and provide a mechanism to select which emulated floppy is mounted on the emulated drive.
References
- Don't be too quick to dump the floppy
- ,PC World says farewell to floppy
- R.I.P. Floppy Disk
- 3.5-inch floppy still available from Verbatim, Imation (3M), and Maxell
- Tribute to Floppy Disk as Sony discontinues production
- Drives are no longer manufactured
- Magnetic recording fundamentals
- Floppy user guide
- Floppy drives PC guide