- USB 3.0

I have more information on connectors, to check and add to this page, and for USB3.0.
The USB cable page on now has good illustrations of the most popular mini and micro connectors, as does the Wikipedia article "Universal Serial Bus". Industry standards such as "IF" (USB Implementers Forum) and "USB On-The-Go define some mini and micro connectors.

For now I cover USB 3.0 at the end of the Cables|Micro Too section. Beware that USB 3.0 is a mess, with some conenctors and cables backwards compatible and some not, and a bizarre siamesed micro connector pair.

Beware that naming of the micro connectors is loose in the industry, and some devices have different wiring in their supplied cables.

Just when you thought things were simple...Just when you thought things were simple...

There are traps with USB.
As well, I'll address memory devices that might plug into USB ports, and related memory devices such as SD card. And detail connector variations.

USB devices may not be handled like other removeable media, thus have higher risk of being used to propagate maliscious software such as spy functions that capture your passwords.
That will depend on design of the USB hub (which may allow direct access to memory) and special software on the device (some legitimate but unwise software lies to the o/s about what type of device it is, so that it gets less scrutiny). A good article by Jesper M. Johansson, titled "Island Hopping: The Infectious Allure of Vendor Swag", is in the January 2008 issue of TechNet Magazine: (it is network oriented but part 1 covers the basic mechanism while part 2 is specific to network issues).
';Two specific notes:
- Windows Vista is a bit better than XP in avoiding automatic running off USB devices.
- The convenience software "U3" provided on some USB memory sticks increases the risk.
Keep your shields up!

And a data loss problem. Windows has a function called "delayed write", in which information is not written to a disk drive or external memory device immediately but kept in RAM until it is not busy with other tasks. I presume that normally Windows takes care of loose ends when it shuts down. However, you may have disconnected your USB device before that. There is a setting somewhere to disable that function (probably called "Optimize for quick removal" in some versions of Properties|Policies for the drive. (Otherwise there's an icon in the Windows "tray" to logically disonnect the drive.)

- USB is not universally foolproof.
(Of course, support was quite limited in Windows 95 except the very last OEM version, much better in Windows 98/SE - however, USB memory sticks usually need a driver installed in Windows 98/SE to work. Do not assume that because one type of device works, such as printer or mouse, that others will. There's also a file system used for memory sticks over 32GB, called eFAT. Recent Apple and Microsoft o/s support that, and an update is available for Windows XP and server products of that vintage.)
- Computer BIOS vary - check for updates.
- If using a port expander, including a docking base, you may have a different controller in the expander which is operating like a hub.
- And you may need to plug your USB device directly into the computer to get it to work.
- It seems that some software expects the device to be plugged back into the same port that it first saw the device on.
- In transferring files from a USB stick recorded by Windows XP to a computer using Windows 98SE I've seen filenames changed to uppercase. That may be a problem since some software, such as web site hosting, is case sensitive. I do not know where the problem is - o/s, USB drivers (which are native in XP but installed for the specific stick in 98SE), or the hardware. Oddly, in one transfer all files with file name extender .htm were changed but the one with .html was not.
- Some makers of USB sticks have stopped supplying drivers for Windows 98SE, which doesn't help users, you may be able to find third-party drivers that work (with the usual precaution of quality and security of what's out on the Internet).
- USB 3.0 (aka "SuperSpeed") has substantial differences from USB 2.0, including a siamesed connector on some devices.
- See FLAKINESS below for apparent incompatibility of computers and stick brands and software.
- and note that the thin USB sticks must be oriented so that the contacts face the plastic block filling the other half of the socket, not the evident metal on the other side of the empty part of the socket. (Makes sense if you look at the inside of a regular USB plug and how that mates with the socket.)

USB 3.0
USB 3.0 standards define siamesed connectors to accomodate both the separate wiring of USB 3.0 signals and the standard USB 2.0 wiring.

The siamesed "micro B" connector at the device end of cables provides USB 2.0 on the wider connector of the pair (apparently a typical "micro B" connector from 2.0 days), and USB 3.0 (aka SuperSpeed) on the narrower of the pair (a small rectangular connector). I don't know if a hard drive maker's standard USB 2.0 micro cable will work for the USB 2.0 functionality. (That is, plug its micro B end into the wide part of the siamesed receptacle. A Western Digital micro B cable fits, but I have not risked trying it under power. Need to check protective grounding.)

The full "B" connector has an attic added to hold the extra contacts, so a USB 3.0 full-size device cable end connector cannot fit in the standard B connector. The USB 3.0 full-size receptacle on devices may accept the standard B connector.)

The USB 3.0 full size A connector scheme looks like the standard USB 2.0 full size A but has five extra contacts just inside the receptacle and at the tip of the plug connector on the cable.) The scheme seems to be that the A end of a device cable can plug into a USB 2.0 compatible computer or a USB 3.0 compatible computer, however I am wary of mixing, I think you want to ensure you have a quality cable as good connections without shorting may depend on precision manufacture.

The cost of the compatibility scheme is more wires in the cable of every device built. And compatibility is not complete as the full size B connector is only one way compatible.

USB 3.0 connectors may have blue plastic colour-code.
In addition to being faster, USB 3.0 handles power differently to reduce consumption and allow recharging of a device whose battery is fully discharged.

- some devices such as 2.5" external hard drives may require more than the 0.5 amp that USB ports are required to provide as a minimum.
You may be able to use a cable that connects to two ports - the extra one to get more power - but beware of the distinction between ports and connectors (two connectors may be supplied by one port inside the computer).
Some computers have a siamesed regular rectangular connector and smaller rectangular connector, the latter for power for the device. The device cable has a single end housing containing two plug shells for the two sockets.
- hubs are available that have their own power supply
- note also that when the computer goes into standby the USB ports will be unpowered. Some software sees that as a problem with the drive, on coming out of standby. Some computers keep the port powered to facilitate charging of devices, apparently the plastic keying block in those ports is yellow in colour.
- beware that some device cables are not fully wired, intended only to charge the device.>/P>

USB memory devices will require drivers for Windows 98SE and earlier operating system.

They may or may not work well. I found that in copying files from XP2 to 98SE using a USB memory stick the file name was changed to upper case letters, in most cases. Then I discovered that the web hosting software was case sensitive, so links to those files did not work.

Kingston have stopped supporting 98SE - they no longer provide drivers, though they refer you to an independent web site for generic drivers.

For context I'll list the versions of File Allocation Table produced by Microsoft. Portable devices are likely to use older FAT types because they use less capable processors than PCs - the maximum storage size, without trickery like Address Translation that fools the o/s about drive size, is limited by the number of bits used for addressing.
- FAT12 is used for floppy disks, for hard drives on the PC-XT computer, and in older devices.
- FAT16 (usually simply "FAT") was used for hard drives beginning with the PC-AT through Windows 3.11. It is limited to 2GB, unless tricks are implemented.
- VFAT was introduced with Windows 95A, the first release of Windows 95 and the only one officially sold direct to users. It is very close to FAT16.
- FAT 32 was introduced with Windows 95A (aka OSR2, apparently there's also a Windows 95B), and is used by later 32-bit versions of Windows. It can handle hard disk drives up to 2 terrabytes. (I don't know what the 64-bit versions of Windows XP and Vista use, I guess NTFS.) FAT32 capacity is plenty for the external/portable devices covered herein. (Obscure note for those doing the math - FAT32 uses 28 bits for addressing, keeping 4 in reserve.))
- Newer Windows and newer/larger external HDDs use NTFS, which is more robust than FAT32. Most drives in recent years should be capable of reformatting to NTFS, I've done that.
Regrets, I don't speak any of the multitude of Apple dialects (O/S versions), I expect there are at least two for Macs.

HOWEVER, USB sticks are more limited than hard disk drives. Limits include: - 2GB, likely to be encountered on devices like photo viewing frames of several years ago.
- 32GB, the native limit of Windows XP.
- above 32GB the eFAT file system is used. While Apple and Microsoft have updates to accommodate eFAT, I find the one for Windows XP does not work properly. Windows 7 does handle eFAT.
(eFAT is optimized for things like USB sticks, not for hard disk drives.)

I find that a USB stick-computer combination may not work.
Sometimes that can be fixed by rebooting.
Some software is sensitive to model of stick, Acronis True Image for example. (Though closing and restarting the software may help, True Image definitely does not like switching sticks live.)
(The need to reboot might, speculating, be due to a "memory leak". Some applications do not properly release memory allocated to them by the o/s when they are closed - Adobe reader is a strong suspect.
But misbehaviour of an application could be a cause, rebooting then first doing what you need to do with the stick should fix that.)

Support for 4GB devices seems variable. For example,
- one no-name SD card was recognized but would only work if formatted to 2GB (FAT16) rather than the FAT32/NTFS required to have 4GB capacity (external memory has tended to be FAT16 or earlier to work with external devices like cameras, even though computers have used FAT32 or NTFS for some time including to support hard drives; the two cases were computers produced circa 2004 with Windows XP2).
- but a new SanDisk SD card of 4GB capacity was not recognized at all by a newer computer, a 2005-vintage Thinkpad x41, unless used with SanDisk's SDDR-113 adapter in a USB port (others have reported the same incompatibility between SanDisk and Thinkpad products and reported that a different brand of SD card worked).
It appears that some computer makers and some card makers have not done their job well, the combination results in no function.

There are adapters to plug SD cards into USB ports (drivers are separate for SD slot and USB port). The adapter has its own firmware which may have defects - check the manufacturer's web site.

Unfortunately, mini- and micro-USB device connectors are mutating.

Cables are available but you have to search for them, and be careful to accurately identify which cable you need - names are confusing, connectors hard to see, wiring can vary.

Herein I normally refer to the end of the cable that plugs into the device in question, such as computer or camera.

Some connector shapes are confusingly named (cable end, male shell, is my best estimate of common naming, I think that A and B originally referred to the computer and device ends of a standard USB cable (rectangular and square respectively) - most often you need a standard computer end and a mini device end - but device-device may be mini-mini. Do not trust the terminology used by sellers to be definitive.

(Many shapes have a plastic insert against one wall of the metal shell and a cavity against the opposite wall which I refer to as the "free" side of the plastic insert. In that shape the contacts are usually leaf contacts on the free side of the insert. (Some other shapes have the contacts in a slot within a plastic insert, perhaps with different contacts each side of the slot, yet others have a central plastic bar with contacts each side. (Keep in mind that contacts each side of a slot or bar are not necessarily independent, they may simply be mirrored - connected to the same wire.)
CAUTION: My notes will narrow down your search but you must actually try them, unless source specifies they are for a certain device (as PC Cables often does). Differences between some shapes are subtle. I've seen wiring vary even in the 4-contact ones that you'd think were standard. You should get a guarantee from the seller that the cable is correct for your exact model of device.

Some device makers do not use standard cables, Western Digital hard drives are suspect in my mind.

Some connectors have additional contacts to the side to contact the shell of the mating connector. (I have not studied the wiring, but in general the shell path is often used for the the cable shield.)

Note that the device may not use all contacts - for example, the mini 8 cable adapting a Nikon camera to a standard computer connector has 8 contacts at the cable but only four at the computer thus either some are not connected or are siamesed (as is often done with signal returns - they are connected to a common ground).

Standard USB connectors are designed with contacts of staggered depth so that power is connected last and disconnected first on insertion and removal. Most mini USB connectors do not have that feature. If you want to be cautious, plug the mini end of the cable in first then the standard end, to avoid electrical erosion of contacts on the device connector that is probably more costly to replace.

The cable end connectors are usually termed "male" because they fit into a larger socket on the device. Adapters are often made to fit the end of a computer USB extender cable (i.e. the adapter has the same large connector as the computer end of a USB cable, over which the extender end fits, and the mini connector to fit into the compact device). Computer extender cables are popular because many USB memory sticks are too wide to fit beside a cable plugged into the adjacent USB port.

Beware that descriptions in catalogues may be imprecise (for example, on the dCables web site, is there any difference between the mini A and mini B 5-contact cable ends?). As well, obviously it is difficult to describe shape in a few words, so compare actual device to actual cables to check match.

There may be colour-coding of the plastic insert, Cables To Go claim that but I wouldn't depend on that from all makers - buy quality.

USB is not intended for long distances. Cables To Go sell extender cables with built-in electronics to provide long length. Noise and signal distortion due capacitance/inductance are typical barriers to long cabling.

And a version of eSATA, eSATAp, can accept USB A and B plugs. (The "p" stands for "power", apparently to supply power to devices.)

Refer to,,, (aka, and for info.

Beware that information herein is not assured, in part because people are sloppy with terminology and some web sites show the wrong illustration of a connector.

Following are various types of mini connectors, using common names for them (I'll cover "micro" later):
- mini A (4): 2 shallow rectangles stacked, no taper between them, plastic in wider part with 4 contacts on free side of it [correction: Panasonic VR RR-US360 actually uses mini B (5)]

- mini A (5): 2 shallow rectangles stacked, taper between them, plastic in wider part with 5 contacts on free side of it (staggered depth). (Compared to the mini B(5) the smaller rectangle is shallow and narrow with tapered sides.)

- mini B (4): square with top corners chamfered, solid plastic in that half with contacts on free side of it. Kodak devices may use this.
(But shows two rectanges with a taper between them and four contacts, using that name - I think that's an error.)

- mini B(5)/mini 5: 2 shallow rectangles stacked, a bit of taper between, plastic in wider rectangle with contacts on free side of it (staggered depth of contacts). [uses include Motorola RAZR V3c cellular phone (Motorola skn6245a is an adapter from standard large device end for such phones; the RAZR V9 uses a "micro" connector instead), some Blackberries including the Bold, WD Passport portable HDD but beware the short cable supplied by WD is wired differently than other devices, Panasonic VR RR-US360, later Fuji cameras, and the Casio QV-R51 camera] (Compared to the mini A(5) the smaller rectangle is deeper and wider.) Sometimes called EMU, at least in the world of cellular phones.
Recognized by the " USB-IF", it may be in the USB "On-The-Go" standard though shallower connectors are in that standard.
Very common, manufacturers were gravitating toward it until the "micro" craze of very shallow connectors was embraced.

- mini 4 rect/flat: deep rectangle with contacts on top of plastic block

- mini-b: The "mini 4" may be what Cables To Go call "mini-b" for many digital cameras, probably early models, especially Fuji. A single rectangle like the full-size USB computer connector but much smaller and narrower compared to height. I have not seen one in person. (It does not sound like the mini XD. Note the "mini B" term is used for at least two other connectors listed above.)

- mini 4P: rectangular with 2 corners rounded, keying notches at one or both bottom corners, contacts in row in center (double sided?) [uses include Planon DocuPen 800 - cable 72811 31533 from is useable or cable adapter CC-406 from HRS-Global of Dorval Quebec is useable]

- mini 5 D: square shape (not staggered) with corners chamfered (D shape if look at it the right way), plastic block at narrower side with contacts facing full width end. May be used by many Kodak cameras and some Olympus but need to check number of contacts.

- mini xD: 2 rectangles, narrow one quite shallow, slot in centre of plastic has several contacts [uses include "most Fuji & Olympus cameras" per package of cable sold by "The Source", but from other information I believe Fuji switched to the mini B(5) on recent models; interestingly Fuji cameras typically use an xD memory card (a bit smaller than an SD)]

- mini 8: three versions I know of:
> single shallow rectangle with top corners chamfered, plastic in bottom with 8 contacts on top side of it (staggered depth). Some people call it "flat 8", some a "flat D" but the corners are flat not curved so "D" doesn't seem right.[uses include many Nikon Coolpix cameras, but some early Coolpix use a 4-contact rectangular with central keying slot judging by photo, may be the mini B (4), perhaps some Pentax cameras, some Panasonic cameras, some Fuji cameras]
> shallow trapezoid with contacts on thin plastic piece at the shorter of the two long sides (noteably the plastic does not fill near half of the shell, whereas most others do), uses include Kodak cameras.
> round with flattened bottom [uses include some Nikon cameras, probably including some Coolpix models earlier than 9600, perhaps fits HP 812, some Panasonic, some Pentax, and Toshiba models as well]

- mini 12: outline is one squat rectangle with chamfer on two top corners, contacts in a rows of 6 on each side of a slot in the cable end.

- mini 14: outline is a large rectangle topped by shallow rectangle, 7 contacts each side of a slot. [in cable end?]

Apparently the connectors shallower than "mini" are referred to as "micro", even though they aren't much smaller.
(Most names from web site, aka
- micro A (5-pin) plug is rectangular, the "male" side has a small rectangular recess with the pins in it and the rest of the housing filled with plastic. May be colour-coded white. CablesToGo (C2G) adapter 27367 may adapt from mini B(5) plug to micro-USB plug.
- micro B (5-pin) is rectangular with a substantial chamfer on two sides, the "male" side has a small rectangular recess with the pins in it and the rest of the housing filled with plastic. May be colour-coded black. shows a "micro A" with shallow rectangle having two rounded corners on one side, and contacts in a slot in the lower half of the plug-shell (cable end). Probably the one used on Motorola RAZR v9 cellular phone, as different from the mini-5 on the RAZR V3c, and middle-vintage Western Digital portable hard disk drives (1TB, whereas 500GB use mini-5 and 2TB use the USB3.0 siamesed connector). Contacts on plug side are in a free-standing projection rather than the one-sided arrangement of larger USB plug connectors, outer two contacts are longer to mate first and break last.
- micro-AB (5pin), which mates with either micro A or micro B cable ends, is a receptacle-only configuration in the "USB to Go" standard. Rectangular even though micro B is chamfered. May be colour-coded gray. (Other cellular phones such as Samsung have a much wider connector of similar shape, with generously rounded corners, having more than 5 contacts.)
CAUTION: I'm confused as to which of micro A and B have the chamfer. The USB 2.0 spec does not display correctly (shifts figures downward), it appears that micro A is usually rectangular and micro B usually chamfered.
- the Samsung Galaxy S7 has a shallow connector with two rounded and chamfered corners, the cord side has a slot in the plastic that is closer to the flat side of the connector, has five connectors wide, I can't see if there are two sets of five (one each side of slot, it appears so but I can't see if the phone has ten contacts (leaf contacts). - there's a siamesed connector pair used by Seagate and Western Digital for USB3.0 external hard drives. It is shallow but in total hardly "micro" in width. Unfortunately some makers list this as a "micro B" connector (which one part of it is, and the USB 3.0 standard refers to it as), sometimes with Super Speed and/or USB 3.0 in the full name. See VARIATIONS|USB 3.0 above for information.

- Firewire 4: rectangle dished in on one side (standard fire-wire is a larger rectangle with one end triangulated, there are 4 and 6-contact Firewire connectors).
- The HDMI video connector looks like a wide version of USB mini A (5), with about 10 contacts.
- HTC company have a rectangular connector with a notch in the bottom.
Note too that some devices run USB through shallow wide multi-contact connectors, such as the Palm universal connector" used on mid-vintage Palm PDAs including the M500 series and early Tungsten models (which may also have signals for traditional computer serial ports; later Palm models split the connections into power and data).

Unfortunately most are 6 feet long, which is excessive for laptop use. (With a few cables and power supply and surge/modem protectors, the user ends up with a bag as large as the small laptop it supports!) Cables to Go has 1 metre/36 inch, 2 metre (~ 6 feet) and 3 metre (~9 feet) lengths.

(But avoid the extra-short that Western Digital is fobbing off on purchasers of the Passport external hard drive series - you need a cable long enough to have your laptop on your lap [what a concept!] but the external drive nearby on a chair or such (previously they supplied 22" length - itself short, as anything less than 3 feet is difficult to use with a desktop computer).)Some retractable versions are available, perhaps solving the need for shortness - stowing compactly.

- The foregoing web sites.
- The "Source" chain of retail electronics stores in Canada have six types.
- has a few including retractables, web site does not have enough detail of mini connector, their 72811 31533 is mini 4P fitting Planon's Docupen 800.
- has a few mini and micro cables
- (or has some cables, including for several camera models (but beware that within a brand like Fuji the connector varies with model, for some cables they provide a line drawing looking end-on). Unfortunately their web site has become more difficult to use.
- lists cables for specific devices and has a page describing the signaling of standard 4-contact USB (the page is labeled "pinouts").
- is more searchable than C2G's web site. - a Canadian dollar store has a couple of adapters, one an uncommon type. Look around for long enough and you may find what you want. Quicker to order on the Internet?
- various companies sell packages of adapters, such as GE and Staples

As usual, quality may vary - for long runs or noisy environments features like the twisted-pair double-shielded (foil and braid) construction of Cables To Go's Ultima USB 2.0 A/Mini-B Cable sound good to me.

Beware that people are sloppy with terminology and some web sites show the wrong illustration of a connector. I recommend you get a return guarantee from a supplier, based on suitability for your specific device.

Intellectual property of Keith Sketchley page version 2017.08.30

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