USB Floppy Disk Drive Emulator

Technical documentation, Troubleshooting, and Configuration

(C) 2009-2010 PLR Electronics

This picture is of a typical USB Floppy unit, that is identical in shape and size and mounting holes to your original floppy disk drive.

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Table of Contents

1. Theory of Operation
2. Floppy Interface
3. Dipswitch Configuration
4. USB Stick Formatting
5. Boot Disks
6. File Chooser
7. Floppy Disk Image
8. Error Diagnosis
9. Data Errors
10. List of Models

Theory of Operation

Review of the floppy disk as a storage medium, and the USB replacement

The USB Floppy product sold by PLR Electronics is a floppy disk drive emulator; emulator meaning it tries to act the same way as a normal floppy disk drive would act, but it is not a 100% perfect emulation because a USB stick is not exactly like a floppy disk.

In reality the floppy disk is an analog device that is used to store digital data; in any situation involving analog recordings, the data size can quickly get out of hand depending on how perfect you want to reproduce it. An example would be an uncompressed recording of a song; it quickly gets into the tens and hundreds of megabytes, even though one song is only minutes long.

In this case, the magnetic platter of the floppy disk is only used to store digital data; the 1's and 0's are easy to convert, but the time stamp and duration of each bit can vary infinitely on the continuous analog track. In short, floppy disks not only hold the digital data but time domain data as well.

The result is that, to represent a standard high density 2 megabyte floppy disk, you may have to use alot more than 2 megabytes; unless you start interpreting the data and storing what you think is important, and in a more convenient and compact form... meaning you discard and lose original data (in this case, time domain data) in the process, saying that you can reconstruct it "good enough".

This is what our standard USB Floppy unit does; for convenience of the users, not only does it interpret the raw analog magnetic tracks, but it also interprets the most common low-level format (the division of circular tracks into packets, each holding X amount of data) and it also interprets the FAT12 filing system that Microsoft DOS made so popular.

Or basically, the USB Floppy has the ability to extract DOS files from the "raw magnetic data" that the host system feeds it, and then copy these extracted DOS files to a FAT16-based USB storage device, and vice-versa. Meaning lots of convenience, that files appear and can be read from your USB stick as if it really were a floppy disk, that you can just stick it in Windows, drag and drop, and then move the USB stick to your CNC machine or whatever, and it sees the recently added files as if they were on a floppy disk all along.

There are downsides to this, specifically a downside when you start interpreting data and restructuring it in a lossy manner. That is, you would need a different program to handle each and every custom way of doing business with a floppy disk, a different interpretor and different set of instructions on how to read and reconstruct any particular way of doing it, as opposed to everyone in the world only using floppy disks in an industry-approved and industry-standard manner (which did not happen).

For instance, at the top level of data, we encounter machinery that, for whatever reason, do not use the DOS-style FAT12 file system format that has become so popular over thirty years that it became a de-facto standard. This means that some machines formatted their floppy disks in a way that would not be readable in a DOS or Windows operating system, because Microsoft chose to be very limited in what kind of filing formats they would support. And, back then when your machine was designed, compatiblity with Windows was very low on the priority list, Microsoft's Windows likely not having been invented yet.

At a lower level, a system designer in the 1980s could have chosen to store the data packets in a non-standard way; this is what the Amiga designers did. Forget reading files in Windows, and your PC is not likely to even be able to load sectors of data at all without help. And this means different interpretors are needed for this.

At a lower level than that, a designer could use different data rates or different encoding methods on the 80 tracks, or even mix which tracks get what kind of encoding method (some designers did). Even more interpretation difficulties for the USB Floppy emulator.

So, the development of this USB Floppy unit will follow a certain path if it is to keep at least some minimum amount of convenience value and try to reach the maximum amount of customers able to benefit; start with the most popular floppy disk file system, FAT12, along with the most popular underlying IBM34 or whatnot type of low-level packet format, along with the most popular MFM or FM encoding method.

In other words, start with the format that 90% of computers and machinery already use and which is fully compatible with each other and with every Windows computer. After that, then work down into the custom jobs, one class of machines after another.

There is already a model released (the 1-G) that has stripped out the top-level FAT12 interpretor, which should provide compatibility with a good percentage of the custom systems. Other systems, such as the Amiga gaming console or musical keyboards or whatnot, and really old industrial machinery that was developed before there were any strong standards, will be on the list somewhere down the road

Again, the other choice is to have really huge floppy disk image files (in the tens of megabytes) just to hold 720kb worth of data; because while every floppy is physically about the same, the structure and timing of how information was stored is machine or designer dependant, and to have 100% compatibility means we have to store every bit of information possible, logical data, timing, any other funny behaviors such as using more than 80 tracks, everything.

The majority of our customers do benefit from the convenience of the FAT12 interpreter (no software needed!), and so we ask patience for those with custom systems, and even ask for help; having data on your custom format, in the form of documents or a non-standard floppy disk shipped to us, goes a long way to getting a solution out faster. Please contact us in this case, if you foresee this becoming a great need in the next year or so. Floppy drives aren't dead but are well on their way...

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Floppy drive electrical interface

The floppy disk drive hardware itself was designed in various ways in an effort to help the floppy drive controller chip designers use their brand or model of drive effectively. And more than one type of floppy control chip were released to the market, and more that one idea how one should go about helping these chips were used.

This means that several different interfaces and behaviors appeared over the years, meaning that floppy drive hardware are not that interchangable depending on the abilities of your host system.

Meaning, to you the customer, the USB Floppy is likely not going to be plug-and-play, unfortunately. There is going to be some amount of configuration to be done per machine model unless we are familiar with your model through enough sales and customer feedback. We have some feedback, and we try to put any machine-specific info on the PLR forums if we can.

At the same time we bring up the existance of floppy disk drives larger and smaller than the now-ubitiquous 3 1/2 standard PC floppy drive. And also of connectors and plugs that are not the standard 0.1" spacing 34 pin rectangular connector, but instead have different amount of pins or use a flat flexible ribbon cable.

This means we must match the size and shape of the floppy drive, then match the connector, then match the data interpretation abilities of the unit, to make any given customer satisfied with his device. Which is why we will generally ask the make/model of floppy drive, the make/model of host machine, and also we ask for any details that will help us guesstimate what you need in case its a machine we do not know; at the very least, is it using a format compatible (readable) with Windows.

As mentioned, matching the electrical layout is something that must be done before the machine even realizes there is a working floppy disk drive in place.

In order to match the USB Floppy unit with as many drive types as possible, a set of dipswitches was added to the board of the USB unit for configuration purposes. The dipswitches are accessable through a slot cut out of the chassis. Use a thin screwdriver or pick to flip the switches, and reset or power down the machine each time they are changed. Sometimes the host machine gets into a strange or confused state because its floppy control software is expecting a signal from the USB floppy that will never come, so sometimes turning the entire machine off everytime a dipswitch is changed is a good idea.

This side picture is of a typical USB Floppy unit, that is identical in shape and size and mounting holes to your original floppy disk drive.

Dipswitches are located in a slot on the top of the USB Floppy unit.

There are eight dipswitches and their behavior is slightly different per model of USB Floppy. Again, the dipswitches control the electronic interface behavior of the USB Floppy, and should be able to handle 95% of possible electronic configurations. We can and have made electrical modifications for those cases that fall into the rare category.

Thankfully only a handful of signals are really important, or popular, and most confusion arises because these same signals are moved around; and manufacturers designed models in the middle years to allow the customer to move each signal where he desired, through jumpers.

The following table is a list and description of the roaming floppy interface signals (not a list of every floppy signal, just the optional ones).

Floppy Drive Interface Description

Signal Name Description
DISK CHANGE This lets the host machine know that the floppy drive has been unloaded and reloaded, with a different or possiblity the same disk. There are several behaviors that have been chosen by the various manufacturers, meaning the signal itself is not cross-compatible 100%. The disk change signal on the 1-IBM is different than the 1-SW.
READY This lets the host machine know that the motor has been spun up to its full speed and the drive is ready for reading/writing. This is dependant on some other signal acting as a start command, either MOTOR ON or DISK SELECT.
HD OUT This lets the host machine know if the disk drive is high density or low density, usually a reading of whether an extra hole is physically punched in the disk plastic, or not. People usually put a solid tape over the hole to trick their machines, if they are out of double density stock. However, since the track width is different for high and double density, "taping" can lead to unreliable performance because its hard to erase a 20-wide track with a 10-wide eraser.
HD IN This is a command from the host machine to the floppy drive, to increase or decrease the amount of power to the read/write heads in case that the high density and double density modes require a different amount of magnetic power, to avoid data corruption between consecutive bits. Also used for differentiating behavior for the inner and outer tracks on the magnetic disk; The inner tracks, just like on a record, are much more compressed in space per bit than the outer tracks are and so magnetic power must be lowered to prevent bleeding to nearby areas.
RPM MODE This is a command from the host machine to operate the floppy drive at 360 RPM instead of 300 RPM. Overseas, the 3 1/2 drives prefer the 360RPM speed, as does the older domestic 5 1/4 floppy disk drive, so some drives were given the ability to change speeds. This has a direct effect on data rate, the number of bits per second seen by the controller. 300RPM can be considered 5 rotations per second, and 360RPM can be considered 6 rotations per second. This behavior also leads to being able to use 3 1/2 drives to replace 5 1/4 or 8 inch stock, as long as you match the RPM.
ED MODE This is a signal that says the floppy drive is acting in Extra Density mode, or 2.88MB. This is not supported so we must tell the host machine that it is not in such a mode.
This is a command from the host machine to the floppy drive to activate the drive (not necessarily to spin the motor, but just let the electronics know to begin operation.). This is used in conjuction with the MOTORA ON, MOTORB ON signals. The floppy disk drives common in the US use this type of signal instead of the DS0, DS1, DS2, DS3 types of signal. Most drives are permanently set to DRIVE B, and you must use a ribbon cable with a twist in the middle of it to switch it to DRIVE A; however most computer PCs nowadays check both lines and assign whoever responds to drive A.
DS0, DS1,
DS2, DS3
The DISK SELECT signal, identical to the DRIVEA/DRIVEB but which are on physically different electrical lines. This is more popular overseas and may have four floppy drives on the same ribbon cable, instead of two, although this is rarely done. Many PCs use this type of drive anyways, because the DS1 setting is identical to the DRIVE B setting.

Many of these signals are optional, and on some drives none of them are not used besides the drive selection signal. These signals can also be moved around on the 34 pin interface, although since most of the interface really had become a strong standard early on, manufacturers put the optional behaviors among the following pins: pin 2, pin 4, pin 6, pin 34. A small segment of drives even put some pins on the odd-numbered lines reserved for ground.

Basically our USB Reader will tell the host (on each of the disputed electronic lines) a simple answer; either yes, or no, or we leave that line alone so the host can control it. Because only a few patterns became popular, our dipswitch system on the USB Floppy will do what it can to fool your host machine into thinking the floppy drive is good enough to work.

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The following is another chart, detailing the dipswitch configurations possible on our configurable model of USB Floppy, the 1-SW, and its sister variants, the 1-F and the 1-G models. Other models do not have so many options and so the dipswitches are disabled, but some dipswitches (5, 7, 8) always work on every model. If you look into the cutout on your USB Floppy emulator unit, you will see the dipswitch structure labeled 1 through 8, and either the top or bottom side will say ON, implying the other side is OFF. Again, use a fine, small tool to flip the switches and be sure to cycle power or at least press the black reset button in the front of the unit.

For more information and recommendations on dipswitches then also look at the floppy drive compatibility chart HERE.

Dipswitch Configuration Chart

Dipswitch Description
DSW 8, DSW 7 These dipswitches together set the maximum size of the emulated floppy disk, usually 720kb or 1.44mb, and the data rate that is seen on the read/write lines. No other dipswitch controls the data rate, so our main concern, after setting this switch, is to properly set the HD OUT line, if it exists (and is required) on your model of machine. It is usually on pin2 or pin4, and may be either high (for 720kb) and low (for 1.44mb), or vice-versa; some disk drives gave the option to invert the signal. It is safest to first try your system at 720kb, since every system should at least support a double density drive, and then to try to match the HD signal with the other dipswitches. Again, many host systems don't care and can figure out for themselves what kind of data rate is coming in. The FAT12 file system structure will also be different for each setting.

The order is: DSW8, DSW7

  • OFF OFF -- 720kb size, 250kb MFM, 9x512, 300 RPM
  • OFF ON -- 1.2mb size, 500kb MFM, 15x512, 360 RPM
  • ON OFF -- same as OFF OFF
  • ON ON -- 1.44mb size, 500kb MFM, 18x512, 300 RPM

Note that the normal USB Floppy models will interpret data written to them and not allow you permanent access to each sector, however the image type of USB Floppy will allow you read/write any sector permanently.

DSW 6 This is not used in most USB Floppy units, except for the 1-G series, because of the extended formats the 1-G is capable of. Leave it ON.
DSW 5 This is the DRIVE SELECT configuration switch. It will make the USB Floppy respond to either DRIVE A, or DRIVE B signals (in the 1-IBM unit), or it will respond to the DS0 or DS1 signal (in the 1-SW and similar units.) This two behaviors are only slightly cross-compatible; setting the dipswitch to DS1 makes it compatible with the computer PC-style of DRIVE B. Set the dipswitch OFF for DS1/DRIVE B, and set the dipswitch ON for DS0/DRIVEA (again, DS0/DRIVEA are NOT compatible with each other, please be sure your drive is matched to your host system by letting us know what kind of floppy drive you have.).
DSW 4 This signal directly toggles the line on pin 4 of the electrical interface. This is not a popular line, usually mostly for HD if pin2 and pin34 are already in use, otherwise unconnected. It deserves some attention if dipswitches 1-3 do not have enough of an effect. The dipswitch OFF leaves the pin4 line HIGH, and dipswitch ON forces the pin4 line LOW.
DSW 3, DSW 2, DSW 1 These lines act in conjuction to do the bulk of the optional interface line configuration.

The order is: DSW3, DSW2, DSW1

  • OFF OFF OFF -- DISKCHANGE on pin 2, HIGH on pin 34
  • OFF OFF ON -- READY on pin 2, HIGH on pin 34
  • OFF ON OFF -- LOW on pin 2, and HIGH on pin 34
  • OFF ON ON -- HIGH on pin 2, DISKCHANGE on pin 34
  • ON OFF OFF - LOW on pin 2, DISKCHANGE on pin 34
  • ON OFF ON -- DISKCHANGE on pin 2, READY on pin 34
  • ON ON OFF -- HIGH on pin 2, READY on pin 34
  • ON ON ON -- LOW on pin 2, READY on pin 34

Note, the dipswitches are only fully active for the USB Floppy's 1-SW model and its variants; the 1-IBM model is intended for modern computer PCs only, or systems based on embedded PCs or that are similar, and so only has DSW 5, 7 and 8 active.

If you wish to try a popular combination first, the HIGH on pin 2, and either DISKCHANGE or READY on pin 34 are the most popular.

Also, pin 6 is even more rarely used than 4 and is permanently set HIGH; this can be an issue for certain host machines, and we have adjusted some units to read LOW on pin 6.

And keep in mind that much depends on your host machine; it was the original designer's choice how many of these options to use, and what floppy disk drive originally was chosen to fulfill his design needs; and later models machines, because of greater computation ability per unit space, tend to require very few if any of these options.

To use the 1-SW model of USB Floppy in an ordinary computer PC, please use the OFF ON ON (3 2 1) setting for dipswitches 1-3, and turn dipswitch 5 off; but it is not 100% compatible and may have problems recognizing disk changes. Use a 1-IBM model instead. If you must use a 1-SW model, be sure to press the black reset button on removal of a USB stick.

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USB Stick Overview

The USB Mass Storage devices, flash or otherwise, usually have several hurdles to overcome for 100% compatibility. First is that the initialization sequence was not clearly designed or enforced enough, so the hardware controlling the USB stick reacts differently to powerup and initialization; Microsoft also did initialization their particular way and many manufacturers tried to follow that over what the USB specifications recommended.

What this means is that the initialization sequence, the method (or several methods) used to start up and use a USB flash storage device, may not apply to every USB stick; our device cannot install a driver for every single USB stick, like Windows can.

The second issue that applies to all devices using USB sticks is that different commands are used for accessing 2GB of data, and greater than 2GB of data. Some sticks will accept the 2GB commands even though their total capacity is 4GB or 8GB or more; and some sticks will only accept 4GB+ commands only, even though you are accessing the first 2GB of the storage unit. This means another uncertainty whether the USB stick will be compatible.

The third issue is that the FAT16 filing system has a hard limit (in earlier versions of windows) at 2GB as well, making 2GB a double barrier, and FAT32 must be used instead which is a significant change in complexity and speed of scanning the file list (a linked list that may traverse all over the place, instead of a simple contiguous table at the beginning.)

So to maximize compatibility there are several recommendations to follow, when you are first trying to get the USB Floppy unit to work in your system:

  • Make sure the first USB stick you try is 2GB or under.
  • Make sure the USB stick is formatted with FAT or FAT16, not with FAT12 or FAT32 or any other filing system.
  • Better known brands and 1GB+ sticks have a better chance at compatibility.
  • Make sure only a few files are on the stick at first, and keep the total underneath the 720kb or 1.44MB limit.

Note that Windows 7 has the ability to format large USB flash drives as FAT/FAT16; meaning a 8GB stick can be formatted to be compatible with devices that expect FAT16.

Windows XP does have the ability to format 4GB+ flash drives as FAT16, but this format program does not seem to work as well as the Windows 7 version. It is in Control Panel/Administrator Tools/Computer Management/Disk Management. You may right click on removable drives and format them as FAT, with a warning that there may be incompatibility issues. If you have some way to remove the partition table on the USB stick first and then do the format, that really helps with compatibility.


The Unix tools dd and mkdosfs have been helpful to some of our customers, dd to wipe sector 0, the partition sector, and then mkdosfs to format. Keep in mind that your USB stick must remain FAT16, so if you go too small with mkdosfs then it will complain and try to force FAT12, which is incompatible with the unit. The minimum I have used is 2 megabytes, using the command: mkdosfs -v -s1 -f1 -F16 h: 4200, where h: would be the drive number of your USB stick; again, getting rid of the partition table in sector 0 allows much more flexibility with sticks. (The main reason someone would want as small a space on the USB stick as possible is if they are working with boot disks and would like to store and duplicate them easily.)

For Windows users there is a low-level formatting tool that is just as helpful to get your stick to be compatible; look at the website HDD and run their low-level formatting tool. Again, wipe the USB stick, not your hard drive. After this you may format FAT16, with either the Window7 format or the Windows XP Administrator format in:
Administrator Tools/Computer Management/Storage/DiskManagement


Warning, do not remove the USB stick while the red light is flashing.

The same safety precautions apply to sticks plugged into our device as it does on a Windows computer, wait for all the blinking lights to stop blinking before pulling out. If the device is locked up for some reason, hold down the black reset button and then pull out the stick.

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Boot Disks

This section pertains only to the standard models of USB Floppy, not any of the image-type models.

Special system disks and boot disks usually work by embedding some sort of program into the first sector of the floppy disk. There is really no room in the first sector for any program of complexity, but there is enough to search for other special system files and load them instead.

If it is not a boot disk, or not boot capable, then at the very least all format programs (fdisk, format, etc.) politely place a text-displaying program that notifies you the user that this floppy disk can't really boot and that you should do something else, such as swap disks and reboot. Some host systems are intelligent enough to scan the drive in the first place, look at that first sector, and determine if it really wants to pass control to this program in sector zero or not. If the host system does pass control to a floppy disk holding gibberish, then it will hang and the user probably has to look for the reset button.

This boot program is stored starting from the very first byte of the first sector (or consider it sector zero); it not stored in any filing system, such as the common FAT12 file system, it has no name, attributes, nothing. It will not show up in any polite listing of the disk drive's contents, although any hex editor such as in Norton Utilities or in a Windows imaging program can easily dump the contents, although none too readable without a disassembler to help out (and not useful to the user anyways).

Because the boot program is not listed properly in the file system it is ignored by the USB Floppy device. This is not a good situation because when you move the USB stick to another computer then the boot program is not moving with it. The USB Floppy, given a new USB flash drive, will create its own boot sector code (because something has to be there in sector zero) and it's nearly guaranteed to be not to your liking.

If you try to create a boot disk on the USB Floppy itself (if you installed it into a Windows computer, for instance), then it will allow temporary changing of all sectors in its memory; however these sectors are not saved as-is but are interpreted and only files in the directory list will be transferred from the FAT12 environment of floppy disks to the FAT16 environment of 2GB flash sticks; and everything else is ignored. Memory is volitile; the memory in the USB Floppy unit will remain only until power is lost or a new stick is inserted; and whatever used to be in the unit's memory is wiped out. Only extracted files stored in the USB stick continue to exist.

This means, until memory wipe, that the illusion of a working boot disk is given; creating a boot disk on a USB floppy and then immediately rebooting will appear a success. Even formatting and writing a complete non-DOS file system will appear a success as well... until power is lost. It is the same concept, that the memory will temporarily store and read back what you have written, but only certain kinds of data gets copied over to the USB stick permanently.

Boot Disk Preparation

So, how to get boot disks working on the USB Floppy? It requires a few things

First, we need a copy of the boot sector. The simplest way is to email the entire boot disk image to us, after extracting from a working boot disk. The shareware program WinImage is one such software which can do this. If you consider yourself experienced with such matters, you can use WinImage or some other hex editor/viewer program to extract sector zero by yourself. Save as a file called "SECTOR00", and it should only be 512 bytes. If you've emailed the disk image to us, this is simply what we are going to do and then we'll place it right back in the disk image, at the end of the file list.

Important: make sure that the boot disk you take the boot sector from is the same size (720kb or 1.44) as what your USB Floppy is configured for, in dipswitches DSW7 and DSW8.

Second, you need to place one of our own files onto your boot disk. This file will ensure, upon a floppy boot, that the USB Floppy will load your extracted boot file into the boot sector, overwriting the generic boot sector that is created on normal USB stick insertion.

These two files can sit anywhere in the file list of your boot disk, ideally last. They are a combined one kilobyte in size, which should be no issue.

Third, and lastly, you must ensure that the boot files you transfer to your USB stick is in the exact same order on the file list; As mentioned before, system disks can only place a large enough program in the boot sector to barely load another file, and so they will take shortcuts, such as only looking at the first or second location of the file list. MS-DOS for example will expect IO.SYS in position one, and MS.SYS in position two. If they are not there in that order, then it is going to refuse to boot.

If you think the way of DOS-based computers booting is somewhat hokey, you are correct; the boot program not being in a file and the other files having to be in a certain order makes creating working boot disks a minor pain.

How this pertains to the USB Floppy, is that when it reads a USB stick for the first time it will start adding files to its internal FAT12 file list in the same order it sees in the USB stick.

And how it is placed on the stick depends on what's already on the stick; a system file added late in the life of a file system is not going to end up in the special slot 1 or 2. It is highly recommended to just format the USB stick so its file list can start fresh, and then start copying your boot disk then.

Side note: Watch out for auto-run viruses. While mostly harmless, they tend to place files on the USB stick whenever they see one pop up, which is not a good way to prepare a boot disk if you only get to the stick second, instead of first. Make sure, in Windows Explorer, that you have checked permissions to see all hidden files and folders and protected files, if you so suspect something is getting on the stick hidden.

An alternative way to prepare boot disks, that can sidestep alot of the above issues, is to use an image program such as WinImage and overwrite the entire USB stick with the boot disk image (note: WinImage will convert your boot image from fat12 to fat16 before storing on the USB stick, which is how this can work; however it is also overly polite, and will refuse to resize many USB sticks.)

Other alternatives involve creating a special sized FAT16 disk image, then plugging your USB drive into a standard computer, and preparing the boot disk via the USB Floppy, not the standard USB port. At this point you may save the image for easy transfer to other sticks; please see the USB stick section above.

While limiting the total size available on the USB stick seems counterproductive, if it's a special boot disk anyways it should really stay special and not for general use.

So, assuming you already have the two special files mentioned before, please follow these steps to create your USB boot disk:

  • Format the USB stick, as FAT. You may quick format.
  • Immediately extract your boot image to the USB stick, or overwrite the USB stick with a boot image (if you have this option).
  • If you want to do it manually, then copy IO.SYS first, and MS.SYS second, and then all other files can go in whatever order. Different boot disks use different system files so contact us if you need to know which order.
  • Copy the two special files to the USB stick, at the end of the list.
  • USB boot disk is ready!

Please only use this USB boot disk in USB Floppy units; although it should be harmless in other computers, and will give an error at boot.

The custom boot loader file is in a zip file here.

And we did note at the beginning that this Boot Section is only for the standard models of USB Floppy, which are the ones with the automatic FAT12-to-FAT16 conversion program. The image-type models naturally keep each and every single sector of data on the disk, including the boot sector; however image files are a little harder to work with, appearing as a solid block of data to Windows instead of individual files. More is explained in the image file section of this documentation.

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File Chooser - Discontinued

This picture is of a USB Floppy optional device, the file chooser.

Discontinued - We are upgrading the file chooser but it is not slated for release for a few months minimum, we apologize for the inconvenience - updated Aug 2013.

File Chooser information below is only for reference, however please look at the 99 Drive product and documentation in the Services tab for an alternative.

The File Chooser is an optional control pad that connects to the front panel of the standard size USB Floppy, with a flexible sized cable. It plugs into the smallest socket marked LK.

With this device plugged in, you can pick and choose which directory will become the new "main" directory visible to your host machine. Or in other words, you can store hundreds of floppy disk-sized folders on your USB stick and then change between them on-the-fly.

The usual way to do this would be to create and name many folders in the main directory, and whenever you want that directory loaded then click on any file inside the sub-directory; all other directories on the USB jump drive will be hidden at that point, until you use the File Chooser again.

It is, in essence, the same as swapping out floppy disks.

You may use whatever name for directories (or folders) you wish, although "DISK1", "DISK2" and such suffices for this example. Try to keep the directory name short, 8 characters or less, or the FAT filing system will rename them in FAT-compatibility mode; LONGNAME, for instance, will be renamed LONGNA~1, LONGNA~2, etc.

When you prepare a new stick for use with the file chooser, then make it easy on the system by clearing the main directory of all files except a placeholder file. Then make all your subdirectories in the main directory, and give all of them placeholder files as well. The File Chooser does not work if you do not have the placeholders, so at least place an empty file called "DISK.txt", "DISK1", "empty.txt", "name.txt", etc, inside every single "floppy" folder.

If done properly, then you should see a list of folders when you activate the File Chooser, and then you enter the one you want, and then select any file inside of the folder. When it's loaded, your system should recognize that a new "floppy disk" has been inserted, and the directory of that "floppy disk" will be the contents of the sub-folder that you had just chosen.

File Chooser Operating Instructions - (discontinued, see above notes)

1. Plug the File Chooser cable into the USB Floppy drive. Turn on your host system, and place a prepared USB stick into the USB Floppy drive.
2. You should be at the main menu of the File Chooser, telling you the version. Version_2.01 is for most models, and Version_2.02 is for image-models only.
3. There are four arrow key buttons, and an OK button, and a Escape button. Press OK twice to get out of the splash screen and to read the USB stick.
4. You should see the main directory of the USB stick, and many subfolders (if you prepared it properly). Use the arrow keys to select a folder, and press OK to enter.
5. You should now see a list of files, or at least the placeholder file. Highlight the file and HOLD the OK button for two seconds, then release.
6. There will be confirmation that the operation is complete!

As for the placeholder file, any type of file will do, and small ones are better because they don't take up floppy disk space. Start the Windows program NOTEPAD and use the SAVE-AS function, and choose a name for the placeholder, "disk01.txt", "designs.001", etc. There need not be any actual text inside the file.

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Disk Image Files

Some of our USB Floppy models work with floppy disk IMAGE files, instead of individual DOS files. This means that if you place the USB stick in your Windows computer, you will not see anything except one large file called FLOPPY00.IMG, sized either exactly 720kb or 1.44mb, or some other size. You can no longer easily access the contents of your "floppy disk", other than to copy or backup the entire thing.

This is a convenience loss for some customers, and if your host system is running a FAT12 filing system then there is likely no reason to lose such ability by using the image type of USB Floppy.

However not every system uses the FAT12 file system, and not every custom system disk could be read in a Windows computer in the first place because of a proprietory format. The image-type of USB Floppy is made for you, and can be compatible with host systems with custom formats..

Even if your host system is compatible with DOS/Windows files, there may be special data storing going on that would be discarded by the FAT interpretor that runs in every non-image USB Floppy unit. Boot disks come to mind, although there is a workaround as noted in the Boot Disk section.

The best part of the Floppy Image style of operation is that the data your host system works with is read and stored "as-is", as a real floppy disk would do, and there is no possible loss of data that goes on when some other program is interpreting what is stored on the disk.

And there are ways to access the internals of a disk image, in some cases; one is by having your image software (such as WinImage) actually "mount" the image file from the USB stick, so that your file FLOPPY00 actually appears as drive A: or drive B: in your Windows system and is fully read/writable, although only if the image has a DOS compatible file system and format.

Alternatively, if you have two USB Floppy units, then you really can transfer non-DOS files from one host machine to another seamlessly.

Image Operation

When you place a freshly formatted USB thumb drive into an image-type of USB Floppy, then your host system will see an unformatted disk. At that point you initiate a FORMAT DISK operation from your host machine, however it is done. At completion the red light will be on a little longer than usual, and after that there will be a new file called FLOPPY00.IMG on your USB stick. The size will be dependant on whether your USB Floppy is configured for 720kb or 1.44mb operation.

If there are any other files besides the image file "FLOPPY00.IMG", then they are ignored and left alone. However, if there is already an image file on the disk called FLOPPY00.IMG then it will be loaded no matter what size your USB Floppy is configured for; a 720kb image placed into a drive configured as 1.44mb will cause the USB Floppy to run its 720kb emulating program, and vice-versa. You will have to remove or delete any such image with your Windows/DOS computer for the USB Floppy to listen to its dipswitches again.

Image drives that have both FAT12 and IMAGE types of behavior can be convenient; because of the issues with boot disks, you can use a USB stick with an image-file only for booting, but then the subsequent standard-data drives can be the usual convenient individual file operate.

Note that the USB Floppy uses a generic image-file; all data and no meta-data, a 720kb image is exactly 720kb. This means you can use images from other sources, or place your own blank images on the USB Floppy drive if you create it with image software such as the shareware WinImage (although they will be DOS formatted images). Note also that the image-type USB Floppy will only recognize the sizes it is programmed for.

What will likely happen is that you are using some custom system and you must format an image first, and when finished then you can transfer your USB stick to the computer to make a backup or master copy of your "blank formatted custom disk" for copy to future USB sticks. Since the name of the file must be same as it always is, we recommend that you create and name folders for each one that you store.

If you have one of the dual models of USB Floppy that can do both images and DOS-interpretion mode, then when it is in image mode it will ignore regular files, and when it is in DOS mode it will likely ignore image files.

Some available data sizes for the image-type are: 640kb, 720kb, 800kb, 1.2mb, 1.28mb, 1.44mb; although this does not tell the whole story about whether they can be compatible with your system or not just by matching data sizes; we need to know the number of sectors per track, the sector size, the data rate and the RPM, at least.

The normal File Chooser is not compatible with disk images, however there is another version of the File Chooser specifically for working with disk images. Let us know which behavior you want.

Also be sure to delete any old image files from your USB stick if you are changing the image size with dipswitches 6-8. Whatever the size of image file is on the USB stick will overrule whatever the dipswitches are set to and you will be unable to create new images of the size you originally configured for until you change sticks or reset the device.

1-G Dipswitch Chart

Dipswitch Description
DSW 8, DSW 7, DSW 6 These three dipswitches together set the size and data behavior of the emulated floppy disk. The 1-G IMAGE model uses dipswitches different than the other models and so is listed here.

The order is: DSW8, DSW7, DSW6

  • OFF OFF OFF -- same as 720kb below
  • OFF ON OFF -- test mode
  • ON OFF OFF -- test mode
  • ON ON OFF -- same as 1.44mb below
  • OFF OFF ON -- 720kb size, 250kb MFM, 9x512, 300 RPM
  • OFF ON ON -- 640kb size, 250kb MFM, 16x256, 300 RPM
  • ON OFF ON -- 1.2mb size, 500kb MFM, 15x512, 360 RPM
  • ON ON ON -- 1.44mb size, 500kb MFM, 18x512, 300 RPM

2-G Dipswitch Chart

Dipswitch Description
DSW 8, DSW 7, DSW 6 The 2-G is planned to replace the 1-G version.

The order is: DSW8, DSW7, DSW6

    720kb size, 250kb MFM, 9x512, 300 RPM

    1280kb size, 500kb MFM, 8x1024, 360 RPM

    800kb size, 250kb MFM, 10x512, 300 RPM

  • ON ON OFF -- (FAT12 MODE)
    1.44mb size, 500kb MFM, 18x512, 300 RPM

    720kb size, 250kb MFM, 9x512, 300 RPM

    640kb size, 250kb MFM, 16x256, 300 RPM

    1.2mb size, 500kb MFM, 15x512, 360 RPM

    1.44mb size, 500kb MFM, 18x512, 300 RPM

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There are status lights in the front of the USB Floppy, one red (marked N/U) and one green (marked FD). Together they can be used to help diagnose issues, with the following chart. Look for a BRIGHT green and red light, there are internal lights in the unit and so the green and red lights may appear dimly lit.

Status Light Explanation

Lights Diagnosis
No red light flicker on power up Check the four pin power plug in the back of the unit.
No red light flicker on insertion of USB stick Cannot initialize, USB stick may be incompatible. USB stick is either not making good contact in the plug, or the USB stick cannot be powered up due to initialization error
Red light is on all the time after insertion of USB stick. Problem with USB stick communications. Try a different stick, or check the format on the current stick, is it FAT/FAT16?
Red or green light is on all the time, period, and no stick is inserted. Problem with the USB Floppy unit. Check your 34 pin data cable if its reversed; it is hard to tell because the red stripe and the writing on the motherboard may be both incorrect, and the best way would be to inspect your original drive before removal and identifying pin1 there. The USB Floppy unit may be damaged if it was plugged in reverse, although in many cases it can survive long enough and the customer can just reverse the cable the other way.
Green light never comes on during a floppy read operation. Dipswitch 5 may be at an incorrect setting. Switch it to the opposite side, cycle power, and try again. Check 34 pin cable if its unplugged. If you have an IBM, then you may need an SW, or vice-versa. If you have an SWF machine, you need a modified IBM unit.
Green light comes on during floppy read operation, but red light does not. No USB stick is loaded, or recognized. Reformat stick if not done so already, or try a different stick. Re-plug stick into the USB Floppy.
Green light and red light comes on during floppy operation, but floppy errors. Check USB stick that it is formatted properly and there are valid files loaded. Change the USB Floppy dipswitch combination DSW1-4 and DSW7-8, as per above table, if not already done so correctly.

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Data Errors

Error Diagnosis
Some files are missing from the directory list Be sure that your total size of files do not exceed what your unit is set for, either 720kb or 1.44mb. The USB Floppy will add files in the order it sees them in the FAT16 directory list, which is not usually the order that Windows will display them, and it will add files until the limit. Single files that are too large are ignored, and subdirectory contents are secondary to main directory contents.
When I remove the USB stick, I still see files The files will remain there in internal memory after the stick is gone, although any data work done on them while the USB stick is not inserted is lost. Pressing the black reset button will clear the memory in most cases
I've changed USB sticks, but the same files are listed You may have incorrect dipswitch settings, particularly the DISKCHANGE signal. Also, some systems may need to read the floppy more than once before updating the file list, although you would have noted this behavior before upgrading to the USB Floppy. If dipswitches cannot cure the problem, then you may have to try a different model unit (others have different type of DISKCHANGE signals).
It was working but I've just formatted the USB stick, and now I get errors when I try to access the USB Floppy You may have formatted it with an incorrect file system. Please re-format as FAT or FAT16, not FAT32.
The Floppy USB was working yesterday with the same exact stick, and I did no changes, but today it is not working Make sure first that the USB stick is still readable in windows; sometime they corrupt due to a static charge or they were removed live. Check also if it not an insertion error; unplug and replug. See if it works sometimes, such as only when you plug it in halfway; the pins may be bent and need replacing. Check to see if there is still power to the unit, are the cables possibly loose.
I cannot get the USB Floppy to boot from a boot disk Please check the Boot Disk section of this documentation.

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USB Floppy Models

The following table is a list of the popular USB Floppy models in current release.

MODEL Replaces Description
1-A Replaces Tajima floppy drives OBSOLETE: Please use 1-SW instead.
1-B Replaces Barudan floppy drives A USB Floppy for Barudan BEMS, Barudan BEMR, older machines with floppy drives. Can support both the DOS format and the barudan FDR format (if you name your files .U01, .U02, .U03, etc., and do not mix them with normal dos files.)
1-IBM Replaces drives SONY MPF920 For ordinary computer PCs, HAAS machines, SWF and Melco embroidery machines, other control panels that use a twisted cable type of floppy connector, or based on a PC using the FAT file format. Most new equipment use this type.
1-SW Replaces drives TEAC FD-235, Panasonic, Mitsumi, Sony MPF420, Epson, Citizen, etc. Workhorse USB Floppy drive that can replace just about any drive on any host machine, so long as its FAT12 based with no other special requirements. Can emulate the 1-IBM drive behavior as well, but not 100%.
1-F Replaces same drives as the 1-SW Variant of the 1-SW, which shows floppy data at all times, even if its blank formatted data when no stick is inserted. The 1-SW in contrast will show no signal at all until the USB stick is inserted, as if there were no disk. Some machines need the behavior of the 1-F.
1-G Replaces same drives as the 1-SW Variant of the 1-SW, which allows any file format to be used (whether custom or FAT12-based), but the convenience of the FAT12-to-FAT16 translation program is lost; i.e., the files stored on the USB stick will no longer be individually viewable in Windows, however the entire representation of the disk is available for copy as a file called FLOPPY00.IMG (popularly called an image file). Must use the common format of 640kb, 720kb, 1.2mb, or 1.44mb.
2-G Replaces same drives as the 1-SW This is a newer unit that combines the abilities of the 1-SW and the 1-G; it has both the FAT interpretor and image-disk capability at the flip of dipswitch 6. Stock should be available shortly.
2-IBM Replaces same drives as the 1-IBM Variant of the 1-IBM which activates the serial communications port in the front, that allows (with an additional adapter unit) one Windows computer running a program to control many of the USB units at once, in a daisy chain.
3-IBM Replaces the TEAC FD-05 A slim type of USB Floppy, intended to replace the laptop sized floppy drives with the 26 pin flat flexible printed cable.
3-OSC Replaces the TEAC FD-04 Variant of the 3-IBM slim type of USB Floppy, intended to be placed in Agilent and Tektronix oscilloscopes.
4 Replaces the NEC FD1138 A replacement for normal sized drives with 26 pins using the standard ribbon cable. Originally intended to replace the floppy drive in the Tajima TMFX.
7 Replaces the Japanese drive NEC FD1137 in the NEC 9801 Does several FAT12 and IMAGE formats at 360 RPM, instead of 300 RPM.

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