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USB (Universal Serial Bus) and FireWire (IEEE 1394) Serial Ports - Page 1

Last updated on 15 November 2007

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Introduction to USB

USB, which stands for Universal Serial Bus, is a high-speed serial standard that, along with FireWire, has almost totally replaced the ordinary serial and parallel standards that have been used to connect peripheral devices to PCs since the 1980s.

Click here! to go to the information on FireWire (IEEE1394) on Page 2 of this article. You can use your browser's Back button to backtrack.

In theory, up to 127 devices can be connected to a single USB port on a computer's motherboard, using only one of a computer's 16 or 23 Interrupt Requests (IRQs), either by daisy-chaining them together, or by using a USB hub, which itself has a number of USB ports.

Enter Interrupt Requests in the Google search box at the top of this page (with its Web radio button enabled) to find links that provide information about them.

Before going any further into this article, read this Q&A on this site: I pushed the FireWire connector into the FireWire port on my PC the wrong way around and fried the iLink board on my camcorder. Use your browser's Back button to backtrack.

Visit the Desktop PCs section of this site for information on how to buy, build, repair, fix, and protect the various types of desktop PCs.

Visit the Laptop/Notebook PCs section of this site for information on buying and protecting them, and fixing problems with them.

A USB hub can have its own power source, or draw its power through the computer to which it is attached. To avoid power problems, a powered hub is the best choice. Seven peripherals can be attached to each USB hub. One of these peripherals can be a second hub to which up to another seven peripherals can be connected, and the second hub can be attached to a third hub, etc..

Along with its data-transfer lines, a USB cable carries a 5 volt power supply so that small devices, such as handheld scanners or speakers, do not have to have their own sources of power.

To view images of USB cables, enter usb cables in the Google search box at the top of this page (with its Web radion button enabled).

The data transfer speeds of the two serial standards are now almost the same. The difference remaining between FireWire and USB 2.0 is that USB 2.0 is still a host-based standard - the devices must be connected via a computer in order to communicate. But FireWire is a peer-to-peer standard, which means that the devices can be connected without going through a computer.

For example, two FireWire cameras or camcorders can communicate with each other without being connected to a computer. A camcorder (an analog or digital video camera) can also send and analog or digital video data to a computer in real time, which means there is enough bandwidth available so that the data is not compressed or error-corrected by hardware or software - the digital video input (or copies of it) can be brought to the screen with perfect digital clarity.

Usually a FireWire connection is used on current computers to allow camcorders to have full control of fast-forward, rewind, and other playback options. A USB connection is usually used to copy still images from the camcorder to the computer. A digital camcorder is a superior to an analog camcorder, because there is no analog-to-digital or digital-to-analog conversion involved, therefore the compression process is less involved. Note that at present even digital camcorders can usually only produce stills of poor quality, largely because of the low-resolution images produced by the Charge-Coupled Device (CCD). But progress is so fast that this situation may well not exist very soon and a camcorder will be able to replace a digital camera. Indeed, it may well be that the manufacturers want to sell both products, so maybe camcorders have been purposefully made so that they can't produce quality still images.

If it is an elderly computer, its motherboard will have a bank of USB 1.1 ports. Most computers manufactured recently have USB 2.0 (USB2) ports. Computers made during the transition between USB 1.1 and USB 2.0 could have motherboards with both types of USB port.

Notebook/laptop computers that cost around £1,200 can have 2, 3, or 4 USB ports, but cheaper models may only have a single USB port, so if you need to make use of more than one USB port at the same time, make sure that you buy a model that has the required number of ports.

The image below, from an MSI motherboard manual, shows where the USB ports are located on the ports panel of an ATX motherboard that also has inbuilt sound and video chips and ports.

All of MSI's motherboard manuals can be downloaded free of charge from http://www.msi.com.tw/. Locate motherboards or mainboards under the Products menu item.

Below is the ports panel of a motherboard with USB and FireWire ports that retains PS/2 mouse and keyboard ports (far left), the parallel port (red), and, below it, a single serial port. The round coloured ports belong to the incorporated sound chip, and the two blocks on the left and right with three ports each incorporate a single FireWire port each (top), and two USB ports. With the motherboard fitted into a PC's tower case, all of the ports appear at the back of the case - aligned vertically. They would be aligned horizontally, as they are seen here, in a desktop case that lies on its side.

USB and FireWire ports can also be built into the case itself. If so, they are either clearly visible in the front of the case, or you have to reveal them from behind a panel that conseals them. Such ports have to be connected by their cables to their respective headers on the PC's motherboard.

The latest FireWire implementation is much faster than USB 1.1, and quite a bit faster than USB 2.0, but FireWire is not yet nearly as prevalent as USB. - A situation that is might change in FireWire's favour over the next few years, because Microsoft originally intended to support FireWire and not to support USB in Windows XP. Then it eventually gave in to the pressure and included support for USB in Windows XP.

Why Microsoft took this line so soon is difficult to understand, because the USB connection - for hooking up a PC to printers, scanners, digital cameras, CD burners, modems, and every other kind of peripheral - has become the most successful interface in the history of personal computers. So much so that USB is shared by both Apple and Windows-based PCs.

Moreover, USB 2.0 will come under renewed attack, because a newer version of FireWire that is twice as fast as USB 2.0 and its own forerunner, known as IEEE 1394b (or FireWire 800 because of its 800Mbps transfer rate), will soon be available on PCI cards and motherboards.

Common questions about USB connectivity answered

USB extension cables

Many different kinds of USB extension cable are available. If your computer only has USB ports at the back of its case it's a good idea to use an extansion cable to make devices, such as a USB flash drive, easier to connect and disconnect. This following page presents the different types of cable very well:

USB extension cables - http://www.usbgear.com/USB-Extension.html

Small USB hubs are also available. I use one that has four USB ports and a short cable so that it connects to a USB port at the back of the case, which is placed close to a wall, and hangs there on its cable, making it easy to connect and disconnect a flash drive.

Switch effortlessly between USB devices

If you use several USB devices, such as printer(s), external drives, a scanner, etc., you can connect them to a USB switch that allows you to choose which of the devices you want active or switched off. The Belkin 4-Port USB Switch can be used together with a USB hub to connect a set of single peripherals to several computers, or connect several computers to a single peripheral USB device.

The following page provides information on such a switch.

Belkin 4-Port USB Switch for Linux, Mac, & Windows -

http://catalog.belkin.com/IWCatProductPage.process?Product_Id=183656

USB and FireWire: Theoretical and actual bandwidths

The bandwidth of each of the interfaces, which is a theoretical or actual measure of the data transfer speeds of an interface, is shown in megabits per second (MBit/s), and megabytes per second (MB/s). There are eight bits in a byte, so dividing MBits/s by eight converts it to MB/s.

Click here! to go directly to information about serial ATA (SATA) external hard disk drives on the second of the Disk Drives pages on this site. Use your Browser's Back button to return to this point on this page.

i.Link is the Sony version of FireWire, which is technically identical to it but uses an external mains power supply instead of taking power through the computer, thereby making it an excellent choice for a notebook owner who doesn't want to run the portable computer's battery down by having to use a power-hungry external device with it.

HOT DOCKING SERIAL DEVICES

Note well that USB and FireWire (IEEE 1394) support hot docking, which allows a USB/Firewire device to be plugged into the motherboard while the computer is running. Windows then loads the appropriate device driver for the device automatically.

USB and FireWire devices are serial devices. All serial devices support hot docking (also know as hot plugging). A serial ATA (SATA) hard disk drives and an optical SATA CD/DVD drives are also serial devices.

Hot docking/hot plugging should never be done with other devices that are attached directly to the motherboard, such as a parallel printer or a keyboard. To attach devices that do not support hot docking, the computer must be switched off, otherwise the sudden extra load on the motherboard could destroy it.

In any case, Windows will not be able to load the appropriate drivers for non-USB devices without being rebooted. However, a standard 33.6K or 56K dial-up modem can be connected to a telephone line while the computer is running, because the extra load is small, and it is dealt with by the modem's circuitry, not the motherboard's. But don't ever try it with a printer or a scanner.

Note that unlike the old 'legacy' serial and parallel ports, USB ports can deliver power to USB devices, so, unless the device is particularly power hungry, it will not require an external power supply.

This feature has caused problems with certain USB modems that draw more power than the USB port can supply, and hence fail while accessing the Internet. So, if you are having connection problems with a USB modem, have a look at its manufacturer's website to find out if it lists the likely causes.

Remember always to only purchase devices the manufacturer's of which have websites. You will then be able to obtain driver updates, and find out about any problems with that device.

Note that a battery-powered computer that uses Advanced Power Management (APM) or Advanced Configuration and Power Interface (ACPI) may experience increased power consumption that leads to a more rapid discharge of battery power when a USB device is attached to it.

The safest way to upgrade RAM: Use the UK and US Crucial Memory Advisors

Paul Mullen, the highly-respected computer guru of the Helpfile at ComputerShopper.co.uk - "I have recently been buying my memory only from Crucial Technology. I would rather pay the extra cost than waste time trying to track down the obscure program faults that bad memory can cause."

The memory requirements of the versions of Windows Vista

Most of the versions of Windows Vista require more RAM memory to run optimally on a computer that doesn't use memory-hungry applications than Windows XP. A video-editing application is an example of memory-intensive software. Only Windows Vista Home Basic has a recommended minimum amount of memory of 512MB, which is the same amount recommended for Windows XP. Windows Vista Home Premium, the most popular version, and Windows Vista Ultimate require a recommended minimum of 1GB (1024MB) of memory, which is twice the amount of minimum memory recommended to run Windows XP. For more information on computer memory, read the RAM pages of this site.

For example, if your computer has an Asus motherboard, open the menu, scroll down to ASUS, and click GO. If, say, you have a Dell computer, scroll down to DELL, and do likewise. You will be taken to the relevant information on Crucial's website.

If you don't know the make and model of the motherboard installed in your computer, here is a good free utility - Belarc Advisor - that creates an analysis of the hardware and software on a personal computer. Look under FREE DOWNLOAD - http://www.belarc.com/. Another utility that also provides detailed information on the memory itself is CPU-Z.

The effect that reinstalling Windows can have on USB drivers

Someone who reformatted the boot drive and reinstalled Windows XP, discovered that the USB ports were not powering devices such as a broadband modem, a webcam, and a scanner, but that a USB-powered memory-card reader did work.

Many but not all USB devices must have their device drivers installed before they're plugged into a USB port, so they shouldn't be plugged in during the reinstallation of any version of Windows that supports USB (any version of Windows 95 from version OSR2, Windows 98, Windows Me, Windows 2000, and Windows XP).

The user could unplug all of the USB devices and perform a repair installation of Windows XP. Visit this site for information on how to carry out such a repair installation. -

http://www.michaelstevenstech.com/XPrepairinstall.htm

Or he or she could unplug the USB devices and perform a full reformat and reinstallation of Windows XP by booting from the Windows CD. Windows XP should not be reinstalled over itself if it is set to use the NTFS file system, because of the following anomaly...

The FAT32 and NTFS anomaly when reinstalling Windows XP over itself

Reinstalling Windows XP over itself by booting from the CD will not remove the customised settings and data, but if the NTFS instead of the FAT32 file system is installed, it will create a new user account - even if you use the same user name as you did when XP was first installed. A new user account will not be created if XP is using FAT32. (XP's native file system is NTFS, but it will automatically use FAT32 if upgraded to from a Windows 98/Me system.) Because of this anomaly, if Windows XP is using NTFS, after the reinstallation you won't be able to access the old user' s My Documents and e-mail files, etc., since each user account is associated with a different Security Identifier (SID) - a unique 128-bit random number generated during the installation process.

Opening My Computer, right-clicking on the C: drive, and then clicking Properties brings up a window that tells you which file system that drive is configured to use in Windows 95/98/Me/XP. The same applies to any of the other hard disk or logical drives listed in My Computer.

See the Recovering Windows XP page on this site if you want to know how to correct the above situation.

The USB Controller

If you are having problems installing a USB device, the first action to take is to make sure that the USB option is enabled in the BIOS and that you have installed the latest USB Controller. This should be available from the PC/motherboard manufacturer's site. While you are there, obtain any other updates. Note that the USB Controller appears as a device in the Windows Device Manager, but the individual USB ports do not.

You can use a USB hub to attach several USB devices to the motherboard via one of its USB ports.

Below is an image of Device Manager from a Windows XP system. Click Image2.htm (or the image itself) to see an image of the Device Manager in a Windows 95/98/Me system, and two images of the Device Manager in Windows XP, the second of which shows the USB Serial Bus controllers category opened. In the image below, the Modems category is shown opened.

USB adapters (adaptors)

Connecting A USB device to a non-USB computer

It can be a simple matter to connect a USB device to a non-USB computer (one that doesn't have any USB ports) when the USB device is a simple one such as a basic mouse, keyboard, joystick, etc.

In cases where the USB device isn't making use of USB's more-advanced capabilities and is simply transmitting exactly the same data as the non-USB version of the device, all that is required is to employ the correct adapter, which connects to and transmits the signals through a non-USB port.

Many manufacturers include a simple "pass-through adapter" with the simple USB device.

If an adapter plug isn't provided with a USB mouse, keyboard, etc., you should be able to buy one for just a few pounds or dollars.

For example, using the Google search box at the top of this page and entering a search term such as ps/2 + usb + converter should produce links to several vendors selling PS/2-to-USB mouse/keyboard converters for under £5/$10 that make it possible to connect a USB mouse/keyboard to a non-USB computer via its PS/2 ports.

Keyboards and mice are inexpensive devices, so it may be cheaper just to buy a replacement that has the type of plug that your computer requires.

More complex USB devices, such as external USB hard disk drives, CD/DVD drives, etc., can't make use of a simple pass-through adapter, because they make use of the much more complex USB signals that can't be converted by any kind of adapter. Therefore, they have to be plugged into a true USB socket.

If you have a complex USB device, such as a network adapter, and your computer doesn't have any USB ports, the solution is to use a PCI USB adapter card. Such an adapter card adds two or four USB ports to a desktop computer (or to a laptop/notebook computer), and is priced at around £15/$25 for the most basic models. It is installed internally in a PCI slot that all computers purchased in the last ten years have.

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Connecting a non-USB device to a USB computer

If you have, say, an older external modem that still works, it requires a classic serial (COM/RS-232) port to plug into.

If your new computer has only USB ports is it possible to buy an adapter that fits to a USB port that allows you to keep on using your external serial modem? And what about being able to continue using older printers, scanners, cameras, serial GPS systems, or the myriad of other devices that connect through a classic serial or parallel port?

If your computer only has USB ports, you should be able to find a suitable adapter.

To use a serial external modem, a special adapter would be required that has a USB connector on one end and a classic RS-232 serial socket on the other and a microchip capable of converting data from the USB format to the RS-232/COM format, and vice versa, thereby allowing high-speed two-way communication through the adapter. Of course, due to the complexity of the conversion, the adapter would require a device driver that makes Windows view it as if it were an ordinary COM port.

Fortunately, dozens of such adapters are available that come with the necessary device drivers. The prices are variable, but you can buy a basic USB-to-RS-232 adapter for between £10/$20 and £15/$30.

Using a search term such as rs-232 + usb + adapter (also adaptor in the UK) in the Google search box at the top of this page should produce many links to local vendors. If rs-232 doesn't work, try using just rs232.

Likewise, there are many USB-to-parallel (printer) port adapters that are used to connect printers, scanners, etc., to USB ports. Using the search term parallel + usb + adapter in the Google search box at the top of this page should produce many links to local vendors.

Therefore, no matter which legacy device you need to connect to a computer that only has USB/FireWire ports, there's probably a suitable adapter available.

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Click here! to go to a table on this site that answers the most common questions with regard to USB connectivity.

RamElectronics has an excellent how-to on adding or enabling USB in Windows, Mac OS X, Linux, Be, and Unix:

http://www.ramelectronics.net/html/usb-howto.html

See below for a few examples of these adapters.

USB-to-parallel-port conversion cables

If you run several devices that use a legacy parallel (LPT) port, you can buy USB-to-parallel-port conversion cables from most reputable component suppliers that make it possible to link them via a self-powered or unpowered USB hub instead of a manual or automatic parallel-port switch box.

You can also buy a USB-to-IDE converter that allows you to connect an IDE hard drive or CD/DVD optical drive to a USB port. If necessary you could probably connect it to USB header on the computer's motherboard so that you can install the drive in a bay in the PC's case instead of as an external drive.

If you need a way to connect a PDA, or other serial device to the USB port on a Windows system or Apple Macintosh, Baffo's USB-to-Serial- Port Adapter is a simple, inexpensive way to do so. The adapter plugs into any USB port on a PC or Mac, and provides one DB9 RS-232 serial port for connection to Palm organisers, Sharp Wizard, Windows CE PDA, or other serial devices.

Google searches

You can make use of the Google search box at the top of this page (with its Web radio button enabled) to search for more information on these conversion cables and vendors for them. For example, for information on USB-to-IDE converters, try using: "usb 2.0" + ide + converter (as is).

You cannot buy a FireWire-to-USB cable

If, say, your notebook/laptop computer doesn't have a port for a FireWire (IEEE 1394) lead, but your video camera does, you can't use a FireWire-to-USB cable to link the camera to the computer. There is no such thing, because FireWire and USB are completely different standards; you can't convert the flow of data of one of them into a flow of data for the other.

Some cameras have a USB port in addition to a FireWire port, but it's only usually used for transferring still images to a computer. You should buy a PC Card FireWire adapter for your notebook computer that usually has two FireWire ports and plugs into the notebook just like any other PC card. You can purchase one from http://www.cableuniverse.co.uk/ for abut £23 [November 2004]. If the FireWire cable that came with the video camera has a standard six-pin connector, you can buy an adapter from the same site that converts it into the compact four-pin version that plugs into the smaller ports found on many recent notebook computers. Look under the FIREWIRE IEEE 1394 heading on that site. Other USB and FireWire cables and adapters are available.

Microsoft supports both USB 2.0 and FireWire (IEEE 1394) in Windows XP

Initially Microsoft announced that it would only be providing support for Apple's FireWire (IEEE 1394) super-fast serial port technology, and would not be providing support for the slower USB 2.0 serial port technology. Microsoft has changed its mind on the matter.

"The new 1394b standard is expected deliver data at up to 800 megabits per second, while USB 2.0 is designed to exchange data at 480mbps.

"USB 2.0 will be 40 times the speed of USB 1.1 and slightly faster than the 400mbps under the current version of FireWire. This means that a file that took 80 seconds to transfer using USB 1.1 theoretically will take about 2 seconds using either USB 2.0 or today's FireWire. With the new version of FireWire, it will take about 1 second...

"Microsoft still doesn't plan to natively support USB 2.0 but will support the standard through add-on drivers."

That was the position before the release of Service Pack 1 (SP1) for Windows XP.

Updated Windows XP SP1 USB Drivers

September 2003 - Microsoft has issued an updated patch for Windows XP SP1 systems addressing additional issues in how it deals with USB 1.1 and USB 2.0 devices. The patch is included in the SP2 update.

Remember to create a Restore Point and/or create a system back-up before you install it - just in case it doesn't agree with your system.

http://support.microsoft.com/?kbid=822603

Microsoft - USB 2.0 support in Windows 98 and Windows Me

The following somewhat misleading information (at the time of writing, "Updated: January 13, 2003") appeared in an article on Microsoft's site:

"Over the past two years, Microsoft has been working with industry partners on the USB 2.0 project. We are pleased to announce that USB 2.0 drivers will be available for Microsoft Windows XP through Windows Update early in 2002. USB 2.0 driver support for Windows 2000 is still under development, and will be available later in the first quarter of 2002. Microsoft will not provide USB 2.0 support for the Windows 9x [Windows 95/98/Me] platform or Windows NT 4.0."

However, with their Service Packs installed, Windows 98 SE and Windows Me both support USB 2.0 - but only if you install the "OrangeWare" device drivers. Microsoft does not supply drivers for USB 2.0 in Windows 98 SE or Windows Me, as the article at the following link states, but third parties do. - See http://www.orangeware.com/.

BipolarBill, chief moderator on the Sysopt.com Forums, had this to say on the subject:

"One thing to note is that there are 5 brands of USB 2.0 chipsets: ALi, Intel, NEC, SiS, and VIA. Orangeware USB 2.0 drivers, which are written for one of those chipsets, will also work in the same brand of chipset. In other words, you don't always have to get Orangeware drivers from a USB card or motherboard maker - you can "borrow" from another maker."

Windows 98 USB Mass Storage Device Drivers (for USB hard drives and flash drives)

You can use a generic USB driver for USB storage devices for Windows 98 that were written by a German programmer called Maximus Decim. It works with a wide range of USB storage devices. There is no home page and no support. To find download sites, you have to enter the man's name in a search engine, such as the Google search box provided at the top of this page (with its Web radio button enabled).

I found the following page that might not exist when you click on its link. If so, try entering the man's name in the Google search box at the top of this page (with its Web radio button enabled).

Windows 98 USB Mass Storage Device Drivers -

http://www.technical-assistance.co.uk/kb/usbmsd98.php

Here is a page that provides useful information on using USB in Windows 98 SE:

Windows98 SE USB Guide - http://www.usbman.com/win98seusbguide.htm

Game-port and USB joysticks

If you use a joystick and a standard game port to play games such as Sidewinder 3.02, it will not work under Windows XP, and Sidewinder 4.0 is not compatible with the game port. You have to use a USB joystick.

Microsoft has decided to make the game port history, so Windows XP only has very limited support for game-port devices. You may be able to configure such a joystick by using one of the standard profiles in XP, but you won't be able to program all of the buttons and hat switches, nor maintain different profiles for each game.

Therefore, if you use a game-port joystick, either don't upgrade to XP, use a dual-boot Windows 98/XP system, or buy a USB joystick. Dual-booting Windows 98 and XP is the cheapest option.

Just remember that you have to have Windows 98 installed first, because, without employing an elaborate fix, 98 won't install if it detects that another operating system is installed.

USB/FireWire and the Linux operating system

The latest Linux distributions support USB 1.1/2.0 and FireWire devices. See these sites for more information -

Linux USB - http://www.linux-usb.org/

Linux FireWire - http://www.linux1394.org/

Note that even though the system (operating system, motherboard's chipset, and BIOS) supports USB/FireWire it does not necessarily mean that a Linux device driver is available for a particular device.

If you require more information on the subject, use the Google search box at the top of this page to conduct a search for usb + linux, or firewire + linux. Use the + sign to add terms that you want to include in the search. Using a minus sign in front of a word removes that word from the search, or a special term such as - waffle gets to the point by removing garbage (not the word "waffle") from the search. You could use the same method to search for Linux USB/FireWire support for a particular device.

Click here! to go the section on this site devoted to Linux, which contains many links to sites.

USB and laptop/notebook computers

Unlike desktop computers, which usually have a bank of two USB ports on the motherboard, laptop/notebook computers usually only have a single USB port.

Powering USB devices from a laptop/notebook computer can often be problematic, because devices such as scanners draw more power than the laptop can provide.

If you are using a USB 2.0 scanner, and you can't get it to install, try disabling any USB 1.1 ports.

If it then installs but won't work, you can purchase a PCMCIA USB card that has the capacity to provide an external power source to the USB ports.

The problem with the above solution is that it limits the portability of the laptop, because the external power source requires to be connected to the mains supply.

External USB 2.0 sound cards

Sound cards that plug into a computer via an external USB 2.0 connection are available and are growing in popularity - especially with laptop computer users.

Creative has such a device on the market. It's called the Audigy 2 NX.

Read about it here! on SoundBlaster.com.

If you have a problem installing a USB sound card, this Q&A on this site might solve it: I can't get my external Creative USB Audigy 2 ZS sound card to work on my notebook computer.

Visit the Sound pages on this site for more information on computer sound and sound cards.

The USB standard specifies a maximum length of 5 metres (approx. 16 feet) for USB cables. Extension cables are available, but are not recommended. If a cable longer than 5 metres is required, it is possible to connect a hub that allows a further 5 metres. Or it is possible to use an 'active repeater' cable - essentially a cable with its own mini-hub built in to one end. You can 'daisy-chain' up to 5 five-metre cables, using 4 hubs, or 4 'active repeaters', plus one plain cable, to give a maximum of 25 metres (80 feet).

See this page for information about USB 1.1 and USB 2.0 cables. -

http://www.usb.org/developers/usb20/faq20/

USB and MS DOS

I received the following e-mail on this subject from Martin Webb.

"I found your interesting USB article, and it explained a few things that I was not aware of. I am a user of Windows XP, but have an interest in DOS. - See DOS: The Alternative Operating System at http://www.mwpms.uklinux.net. Although, as you say, USB is not supported in DOS, there are ways to get external mass storage devices, and floppy drives recognised."

The forum at http://www.computing.net provides information on USB in DOS.

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On its own, MS DOS can't know anything about USB devices because USB as a standard came out long after DOS, and Microsoft has not added USB support to the versions of DOS that still form the bedrock of Windows 95/98/Me.

This can be problematic if you boot to DOS, or start a computer from a DOS boot floppy disk and then find that your USB keyboard and mouse no longer function. The computer will start but you won't have any way of controlling it. Even if the keyboard and mouse work fine in DOS due to a setting being enabled in the BIOS, or by using the manufacturers' DOS drivers, you probably won't have access to USB peripherals such as a USB printer, external hard disk drive, or CD/DVD burner.

Although there is no single, universal fix that provides USB/DOS support, there are solutions for each device. For example, you may be able to enable DOS support for a USB keyboard through a USB/Legacy option available in the computer's BIOS setup program, access to which is achieved by pressing the DEL or some other key specified on the start-up screen to enter SETUP during the first few seconds of the start-up. Once in the BIOS setup program, search the settings that relate to USB, for a "legacy" option. If available, simply enabling it can allow you to use a USB keyboard in MS DOS. If the option isn't available or doesn't work, try visiting the keyboard manufacturer's website. It may provide an MS DOS driver for that make and model of keyboard. Alternatively, your computer's original manufacturer's set-up CD(s) may provide DOS drivers, because sometimes they are included with a fairly recent computer in order to enable the use of a USB keyboard or mouse with the DOS-level system-recovery software.

Tip: If you put the hidusb.sys file on a boot floppy disk and boot the system with it, the USB mouse should work. I discovered that when I tried to use a USB mouse in Windows 98 SE with DOS-level Drive Image and discovered that the PS/2 mouse driver wouldn't work. Hidusb.sys is a Microsoft USB driver originally from Windows 98 that is also included in later versions of Windows.

Apart from checking the website of the manufacturer whose USB device you're trying to get to work in DOS, as a starting point for your search for DOS USB drivers, try visiting http://www.usb-drivers.com/, which lists thousands of USB drivers and related files from hundreds of vendors.

If you're still at a loss, you can search for other sites by entering usb + dos + drivers in the Google search box at the top of this page.

Using a USB cable to transfer files between two computers

It's possible to transfer files - or even a backup image of a whole system created by using programs such as Norton Ghost or Drive Image - via a USB cable that links computers together.

Visit http://www.windowsnetworking.com/.../usbmain.html for a full explanation.

Portable USB back-up drives

New compact portable backup storage devices that plug into USB ports are now available. Plextor calls its USB storage devices Flash Drives. Iomega also makes them. They are also called Micro Vaults, or just memory sticks. This peripheral device looks much like a wireless USB network adapter that you just plug into a USB port. You can take it out and plug it into any other computer that has the device's drivers installed.

Computer Shopper has given the drives a five-star rating. Plextor drives of three capacities are available - 128, 256, and 512MB - that cost £58, £106, and £211 (June 2003) respectively from Dabs in the UK.

Pen drives, thumb drives, jump drives, keychain drives, they carry many different labels, and they can employ varied technologies, but they all have a few features in common: they're compact, removable drives that attach to a computer via a USB port to add anywhere from 16MB to over 4GB of portable back-up storage to a computer.

In operation, all these USB drives can act much like an ordinary floppy or hard disk drive. Many of these devices are even bootable, if the computer they're installed on is recent enough to allow booting from a USB device. The newest operating systems such as Windows XP, Windows 2000, and some Linux distributions, can automatically recognise and mount one of these USB drives, assigning the next-available drive letter to it. Older operating systems, such as Windows 98, may require a driver to recognise this kind of USB drive, but every USB-drive vendor I've investigated provides such drivers at no extra cost. Free and open-source drivers are also relatively easy to obtain.

Here are some other examples of these drives, most of which look like ordinary small laptop-sized hard disk drives with a USB flash drive attached to them:

The Lacie USB Mobile Hard Drive - retail price, in June 2004, only £87. There are 40GB, 60GB ,and 80GB versions available. Power can be drawn from an additional USB socket or a PS/2 connector when the USB 2.0 data connection doesn't supply enough power. A USB connection draws power through the computer, which, if it is insufficient has to be boosted by using an external self-powered USB hub, or by alternative methods.

The Freecom FHD-XS is a external 20GB hard disk drive - retail price, in June 2004, £130 - is housed in an aluminium case. The USB attachment is retractable. Given a five-star product rating by Computer Shopper.

High-speed, high-capacity USB 2.0 flash drives

The smaller of the high-speed USB CompactFlash drives (64MB, 128MB, 256MB), known by several names such as thumb and pen drives, have enough permanent flash memory to make them a viable on- and off-site back-up option for data files. The drives with the highest capacities now have enough flash memory to store an entire system made up of the operating system, the applications it runs, and the data files that the applications generate. Current drives offer capacities between 1GB and 4GB, with 8GB capacities on the way, with, of course, the promise of still larger drives in the future.

Crucial, Corsair, Kingston, and other memory manufacturers have brought out lines of inexpensive second generation USB 2.0 thumb drives that are smaller, faster, and weigh less than the previous generation. The pen drives are no wider than their USB 2.0 connector, which is accessed by removing the drive's cap.

Visit the US http://www.crucial.com/ site or http://www.crucial.com/uk for the UK site to see examples of the flash drives Crucial sells.

To lose data on burned CD/DVD disks only requires the disk to be damaged or scratched, and it is known that recorded disks have a limited shelf life that can be as low a five years for cheaper makes of disk.

However, Flash drives are very durable, and the data stored in one will remain intact as long as the drive can be accessed, which is effectively for as long as there are computers that have USB 1.1 or USB 2.0 ports, because the drives can work on the earlier and slower USB 1.1 ports. It is known that the drives can survive and still be accessed after having gone through a full washing cycle in a domestic washing machine.

Tha data reading and writing rates vary from drive to drive, but they are fast. For example, Kingston's Data Traveler Elite has nearly a 20MB/s (20 megabytes per second) reading rate, and up to 12MB/s writing rate, and has integrated data protection by providing optional 128-bit DES hardware encryption. Corair's Flash drives have a reading rate of almost 20MB/s, a writing rate of 14MB/s. Moreover, the rubber cladding around them makes them waterproof and well suited for outdoor use.

Click here! to go to more information on flash drives on this site.

USB MP3 players

It's possible to buy a high-capacity USB MP3 player that can transfer data as well as music. Connecting a USB MP3 player via a USB 2.0 port provides high-speed data transfer between a computer and a USB MP3 player, allowing a user to play MP3 audio files and and to use it as a handy external hard disk drive. Players with Direct USB are also available. This allows the charging of the internal battery via the USB port without the need for extra cables.

The connection is amazingly fast, allowing you to transfer up to a song per second, but the computer must have a USB 2.0 port in order to make use of the fast USB 2.0 transfer rates. If the computer has only standard USB 1.1 ports, a USB 2.0 MP3 player can still use it, but the files are transferred at the much slower USB 1.1 data-transfer speed.

How much music can a given MP3 player store? - The basic rule of thumb is one megabyte holds one minute of music. That is, for every megabyte of memory, you can store about a minute of compressed music at near-CD quality.

There are three basic types of memory that MP3 players use: removable or embedded flash memory, or a hard disk drive.

Flash memory is rugged and very compact, and, because it is solid-state memory that has no mechanical moving parts, the player can't skip. Therefore, players that use flash memory are the best choice for listening to music during activity, such as jogging.

Examples of removable flash memory include the Secure Digital card and the MagicGate Memory Stick Duo. The benefit of using this type of memory is that to add storage capacity you just buy more cards. Embedded flash memory is built into the MP3 player itself. Some MP3 players can use both removable and embedded memory.

A third category of MP3 players store music on a miniature hard disk drive (HDD), of the kind used in a computer, but smaller. MP3 players with HDDs can store many times more music than players using flash memory — up to a thousand hours of audio or more — but they also tend to be a bit heavier. Their large LCD screens are often backlit, and their interfaces are designed to provide easy navigation through an entire music library consisting of hundreds of files. Since HDDs are mechanical devices that contain moving parts, they can be susceptible to skipping. However, most hard-drive MP3 players use memory buffers that virtually eliminate skipping.

To locate vendors and information on these products, enter a search term such as usb + mp3 + player in the Google search box at the top of this page, or try clicking this link with an inbuilt search:

http://www.google.com/search?q=usb+mp3+player

A good system for video editing

A company that I know of does a great deal of video editing. It's staff use a digital camcorder to shoot video footage, which is downloaded on to a computer using a FireWire connection in the AVI format. When the video has been edited using specialised software, the Windows Media Encoder is used to compress it into the Windows Media Format, because this has been found to produce the best compression-to-quality ratio. The computer being used runs an Intel Pentium 4 1.7GHz processor, 256MB of DDR RAM, and a 40GB SCSI hard disk drive that runs at 10,000 rpm, with the Windows 2000 Pro SP2 operating system.

For editing video, the capabilities of the software package is as important as the speed of the hardware.

Google web searches

Entering usb or firewire or usb + troubleshooting, etc., in the Google search box at the top of this page will bring up enough pages to keep you reading about the subject all day.

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PC Buyer Beware! Copyright © Eric Legge 2004-2008. All rights reserved.