DiscFerret - User contributions [en]

DiscFerret:FAQ

2012-05-11T04:20:49Z

Adtpro: Added Shugart/IBM interface

[[Category:DiscFerret]]

== DiscFerret-specific questions ==

=== What kinds of disk drives can I plug into a DiscFerret? ===

The DiscFerret will adapt to any 34-pin Shugart or IBM interface drive, or any 50-pin Shugart interface 8" drive with adapted cable or a [http://www.dbit.com/fdadap.html FDADAP] adapter.

The DiscFerret connects to 5-1/4" and 8" disk drives via a standard 34-connector floppy disk ribbon cable. These cables typically connect to a drive with a card edge connector, and have a "twist" at the floppy end. These cables were common in systems before hard drives became prevalent. They resemble a 40-connector IDE hard drive cable, but are smaller by 6 pins. They were commonly called "FD" (Floppy Disk) or "FDD" (Floppy Disk Drive) cables.

Disk drives that have been used with the DiscFerret:

* TEAC FD-55GFR - 5-1/4", high-density (1.2 MB)

=== Why another disc analyser? ===

Because the other analysers weren't good enough! The Catweasel Controller (all four versions of it) are essentially unsupported by the manufacturer. Developer support has tended to be poor, with little hardware documentation available. On top of all this, the drivers only allow discs to be written on machines running Linux 2.4 (a very old Linux Kernel release which has been essentially abandoned since the mid-2000s) or MS-DOS.

Ultimately I wanted to create a hardware-based disc reader/writer which could be used on any system with a Full-Speed-capable (12Mbps) USB port. Whether that is a PC, a Mac or some other platform is entirely up to you, but in general, if it runs Linux, supports USB and has a libusb port, it'll most likely work fine. This even extends to embedded systems like the [http://beagleboard.org/ BeagleBoard], as long as you add some form of storage (e.g. a USB thumb-drive or hard drive).

=== So it's a Catweasel clone then? ===

Not at all -- the DiscFerret was engineered completely from the ground up, and provides a lot of features that the Catweasel is simply incapable of:

* '''Significantly increased timing resolution'''. The DiscFerret acquires timing data with a resolution of 10 nanoseconds, for the first time allowing MFM and RLL hard disc drives to be imaged at transition level. On a Catweasel Mk3 or Mk4, the maximum clock frequency is 28.322MHz (about 35ns resolution), with 14.161MHz (70ns) and 7.080MHz (140ns) as options. DiscFerret uses a 100MHz sample rate, providing single-nanosecond timing resolution, and is accurate enough to write a disc with software precompensation (where write-precompensation is applied before the disc is written).
* '''Maximum timing period limited only by available RAM'''. The DiscFerret can store up to 524288 bytes (that is, 512 binary kilobytes) of acquisition data, or a maximum count of over 67 million timer ticks. This equates to an acquisition time of nearly a second (a disc typically rotates in around a fifth of a second)! The Catweasel is always limited to 128 counts per period, meaning that the acquisition clock must be slowed down when imaging at lower bit rates, or the hardware counter will overflow.
* '''Hardware-based reading and writing of hard-sector discs'''. Literally "set it and forget it" -- enable the track-mark detector, specify how many sectors to skip (if any), and how many sectors to read, then trigger the acquisition. Simple!
* '''MFM sync-word (sequence) detection with "don't care" bits'''. This is exactly what the name suggests: a module which allows the DiscFerret to scan the incoming data stream for a specific bit sequence, then start or stop the acquisition. Bits can be masked off (ignored) if necessary, which allows for ranges of sync-words to be specified. The start and stop masks and sync-words can be specified completely independently of each other.

=== What happens if I use the wrong power supply? ===

In most cases, nothing. The DiscFerret incorporates a reverse-polarity protection circuit, which reduces the risk of damage due to the use of an incorrect power supply. This circuit has been tested up to 20V, which exceeds the input voltage rating of the DC power connector, and the output voltage of most off-the-shelf DC power supplies.

In the event of a reverse-polarity event, the power light on the power supply (if present) will be lit, while the power light on the DiscFerret will not (as the protection circuit is preventing the power from reaching the DiscFerret).

It should be noted that the protection circuit is intended as a last-resort safety device, and should not be "tested" or "tried out" by the end user. In situations where the DiscFerret is exposed to both reverse polarity and extreme overvoltage, the protection circuit may fail to operate. Always use the power supply which was supplied with the DiscFerret, or an identically-specified replacement.

If a higher-voltage power supply is attached to the DiscFerret, the "12V" output on the power output connector will rise to match the input voltage. The 5V output will remain at 5V (except in cases of extreme overvoltage). Once again, your DiscFerret will probably survive, but your disc drive almost certainly won't...

=== How much power does the DiscFerret need? ===

The DiscFerret requires a 12V power supply, with a maximum current consumption of around 1.5A if powering the DiscFerret in "stand-alone mode" (where the power output socket is unused). This increases to around 3.5A if an external drive is being powered from the DiscFerret's power output socket, assuming the drive is consuming the maximum allocation of 1.5A on both the 5V and 12V power outputs.

If the external +12V output is not being used, the input voltage can be increased to a maximum of 15V DC, making it possible to run the DiscFerret from a standard 13.8V battery pack. It is, however, inadvisable to use an automotive ("cigarette lighter") power socket as a power source, due to the large amount of electrical noise present on motor vehicle power supplies.

=== How do I buy a DiscFerret? ===

You can buy a DiscFerret through the [http://store.discferret.com/ DiscFerret Store].

== Questions about the DiscFerret Wiki ==

=== Why can't I edit pages? ===

To try and prevent the Wiki from being 'spammed' (filled with unsolicited advertising and other garbage), editing has been restricted to registered users only. It's very easy to become a registered user -- simply scroll up to the top of this page, click the "Log in / create account" link at the top right, and follow the instructions.

Some high-traffic pages are edit-restricted (notably the home page and the pages in the DiscFerret: hierarchy). If you need to have one of these pages modified, please leave a message on [[User_talk:Philpem]].

DiscFerret:FAQ

2012-05-10T20:32:34Z

Adtpro: Added a blurb on what to plug into the darned thing... please add the drives you use!

[[Category:DiscFerret]]

== DiscFerret-specific questions ==

=== What kinds of disk drives can I plug into a DiscFerret? ===

The DiscFerret connects to 5-1/4" and 8" disk drives via a standard 34-connector floppy disk ribbon cable. These cables typically connect to a drive with a card edge connector, and have a "twist" at the floppy end. These cables were common in systems before hard drives became prevalent. They resemble a 40-connector IDE hard drive cable, but are smaller by 6 pins. They were commonly called "FD" (Floppy Disk) or "FDD" (Floppy Disk Drive) cables.

Disk drives that have been used with the DiscFerret:

* TEAC FD-55GFR - 5-1/4", high-density (1.2 MB)

=== Why another disc analyser? ===

Because the other analysers weren't good enough! The Catweasel Controller (all four versions of it) are essentially unsupported by the manufacturer. Developer support has tended to be poor, with little hardware documentation available. On top of all this, the drivers only allow discs to be written on machines running Linux 2.4 (a very old Linux Kernel release which has been essentially abandoned since the mid-2000s) or MS-DOS.

Ultimately I wanted to create a hardware-based disc reader/writer which could be used on any system with a Full-Speed-capable (12Mbps) USB port. Whether that is a PC, a Mac or some other platform is entirely up to you, but in general, if it runs Linux, supports USB and has a libusb port, it'll most likely work fine. This even extends to embedded systems like the [http://beagleboard.org/ BeagleBoard], as long as you add some form of storage (e.g. a USB thumb-drive or hard drive).

=== So it's a Catweasel clone then? ===

Not at all -- the DiscFerret was engineered completely from the ground up, and provides a lot of features that the Catweasel is simply incapable of:

* '''Significantly increased timing resolution'''. The DiscFerret acquires timing data with a resolution of 10 nanoseconds, for the first time allowing MFM and RLL hard disc drives to be imaged at transition level. On a Catweasel Mk3 or Mk4, the maximum clock frequency is 28.322MHz (about 35ns resolution), with 14.161MHz (70ns) and 7.080MHz (140ns) as options. DiscFerret uses a 100MHz sample rate, providing single-nanosecond timing resolution, and is accurate enough to write a disc with software precompensation (where write-precompensation is applied before the disc is written).
* '''Maximum timing period limited only by available RAM'''. The DiscFerret can store up to 524288 bytes (that is, 512 binary kilobytes) of acquisition data, or a maximum count of over 67 million timer ticks. This equates to an acquisition time of nearly a second (a disc typically rotates in around a fifth of a second)! The Catweasel is always limited to 128 counts per period, meaning that the acquisition clock must be slowed down when imaging at lower bit rates, or the hardware counter will overflow.
* '''Hardware-based reading and writing of hard-sector discs'''. Literally "set it and forget it" -- enable the track-mark detector, specify how many sectors to skip (if any), and how many sectors to read, then trigger the acquisition. Simple!
* '''MFM sync-word (sequence) detection with "don't care" bits'''. This is exactly what the name suggests: a module which allows the DiscFerret to scan the incoming data stream for a specific bit sequence, then start or stop the acquisition. Bits can be masked off (ignored) if necessary, which allows for ranges of sync-words to be specified. The start and stop masks and sync-words can be specified completely independently of each other.

=== What happens if I use the wrong power supply? ===

In most cases, nothing. The DiscFerret incorporates a reverse-polarity protection circuit, which reduces the risk of damage due to the use of an incorrect power supply. This circuit has been tested up to 20V, which exceeds the input voltage rating of the DC power connector, and the output voltage of most off-the-shelf DC power supplies.

In the event of a reverse-polarity event, the power light on the power supply (if present) will be lit, while the power light on the DiscFerret will not (as the protection circuit is preventing the power from reaching the DiscFerret).

It should be noted that the protection circuit is intended as a last-resort safety device, and should not be "tested" or "tried out" by the end user. In situations where the DiscFerret is exposed to both reverse polarity and extreme overvoltage, the protection circuit may fail to operate. Always use the power supply which was supplied with the DiscFerret, or an identically-specified replacement.

If a higher-voltage power supply is attached to the DiscFerret, the "12V" output on the power output connector will rise to match the input voltage. The 5V output will remain at 5V (except in cases of extreme overvoltage). Once again, your DiscFerret will probably survive, but your disc drive almost certainly won't...

=== How much power does the DiscFerret need? ===

The DiscFerret requires a 12V power supply, with a maximum current consumption of around 1.5A if powering the DiscFerret in "stand-alone mode" (where the power output socket is unused). This increases to around 3.5A if an external drive is being powered from the DiscFerret's power output socket, assuming the drive is consuming the maximum allocation of 1.5A on both the 5V and 12V power outputs.

If the external +12V output is not being used, the input voltage can be increased to a maximum of 15V DC, making it possible to run the DiscFerret from a standard 13.8V battery pack. It is, however, inadvisable to use an automotive ("cigarette lighter") power socket as a power source, due to the large amount of electrical noise present on motor vehicle power supplies.

=== How do I buy a DiscFerret? ===

You can buy a DiscFerret through the [http://store.discferret.com/ DiscFerret Store].

== Questions about the DiscFerret Wiki ==

=== Why can't I edit pages? ===

To try and prevent the Wiki from being 'spammed' (filled with unsolicited advertising and other garbage), editing has been restricted to registered users only. It's very easy to become a registered user -- simply scroll up to the top of this page, click the "Log in / create account" link at the top right, and follow the instructions.

Some high-traffic pages are edit-restricted (notably the home page and the pages in the DiscFerret: hierarchy). If you need to have one of these pages modified, please leave a message on [[User_talk:Philpem]].

DiscFerret

2012-04-26T17:25:54Z

Adtpro: Trimmed the background from the image of the board, turned up the contrast a little.

'''The first prototypes of the DiscFerret hardware are now in the hands of developers -- we're aiming for full production around mid-Summer or early Autumn! Keep checking back, and feel free to join us in [http://webchat.freenode.net/?channels=discferret #discferret on irc.freenode.net]'''

'''If you're interested in developing software for the DiscFerret, or even just testing it and providing us with feedback, please contact Phil at phil@discferret.com. Parts are being procured, and several Limited Pre-production (LPP) units will be assembled for sale within the coming weeks. Get your orders in early, they're sure to sell out fast!'''

DiscFerret is a combination of hardware and software that allows a standard desktop computer to read, analyse and decode the data on almost any floppy disc, and most MFM and RLL hard disc drives. This includes standard formats like PC DOS, but also more unusual formats like AmigaDOS, Apple (II and Mac GCR) and also more esoteric formats like those used on the Intel MDS/ISIS, Northstar and Sirius-Victor 9000 platforms. Imaging is performed at the lowest possible level -- that of magnetic transitions, which allows everything which can be represented on-disc to be imaged for later analysis.

The source code and CAD files for the DiscFerret design are completely open-sourced: the hardware and software are released under the GNU GPL (in the case of the [http://hg.discferret.com/hardware/file/tip/LICENSE board], [http://hg.discferret.com/microcode/file/tip/COPYING microcode], and [http://hg.discferret.com/firmware/file/tip/COPYING firmware]) or the Apache Public Licence (in the case of the [http://hg.discferret.com/C-API/file/tip/LICENSE DiscFerret Hardware Access Library]).

An IRC channel for support and development has been established. Please join us in [irc://irc.freenode.net/#discferret #discferret on irc.freenode.net].

[[File:Discferret_board_component_side_HD_c.png|center|600px|DiscFerret board]]

== News ==
2012-APR-17 -- We've been helping out the Prince of Persia Source Code Recovery Project! The DiscFerret Project supplied a DiscFerret 1A24 prototype unit, which successfully produced images of several source code disks. We're now hard at work analysing and decoding the contents of these images... See the '[https://twitter.com/#!/search/%23popsource #popsource]' hash-tag on Twitter for more information! -- [[User:Philpem|Philpem]] 22:30, 17 April 2012 (BST)

2012-JAN-11 -- DiscFerret Microcode 0028 and C API v1.5 have been released and are on the [[DiscFerret:Downloads|Downloads]] page. These releases fix several critical microcode bugs -- users should update to these releases as soon as possible. --[[User:Philpem|Philpem]] 21:50, 11 January 2012 (GMT)

2011-DEC-31 -- DiscFerret Microcode 0026 and C API v1.3 have been released and are on the [[DiscFerret:Downloads|Downloads]] page. [[User:Philpem|Philpem]] 21:43, 31 December 2011 (GMT)

2011-DEC-23 -- DiscFerret development has now resumed after a "brief" hiatus. Microcode updates are on the [[DiscFerret:Downloads|Downloads]] page, and the source code is available from the usual place (http://hg.discferret.com/). --[[User:Philpem|Philpem]] 02:44, 23 December 2011 (GMT)

2011-MAR-21 -- The DiscFerret now supports 8-inch disc drives. Support has been added to Microcode 0x0021; the source code for this is in the "microcode" repository. -- [[User:Philpem|Philpem]] 01:22, 21 March 2011 (GMT)

== Links ==

* [[DiscFerret:FAQ|FAQ]]
* [[DiscFerret:Downloads|Downloads]]

* [[:Category:Disc formats|Disc format documentation]]
* [[:Category:Disc image files|Image file format documentation]]

File:Discferret board component side HD c.png

2012-04-26T17:23:43Z

Adtpro: DiscFerret board with a little transparency added

DiscFerret board with a little transparency added