KarbosGuide.com. Module 5c2b.

About USB - continued

The contents:

  • The USB hub
  • The USB devices
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  • The USB hub

    We should be able to connect 127 units all together. An important unit is the hub, as we know it from the ethernet. The USB hub may be found in the keyboard or in the stand of a monitor like in my Sony F400. IT holds four USB ports, here you see two of them:

    This is smart, since the monitors is on the desk where you need to connect the camera or whatever. Also the USB hub needs power, which already is in the monitor.


    The USB cabling can deliver 500 mA of power. This is sufficient to feed a keyboard or other low powered units. For instance my Canon FB630U scanner is only connected by one USB cable. The scanner gets gets power from the pc through the USB cable.

    One cable is enough for both data and power supply. Scanner Canon FB630U

    But it is not enough for multiple units, therefore we will need powered hubs.

    Shared USB units

    Another interesting aspect is that USB allows shared peripherals. This means that two PCs can share a USB unit. Or you may even use the USB for a low-priced network connection.

    The products

    The PC 99 guideline from Intel and Microsoft recommends a hardware design without an ISA-bus. The guideline is a recommendation to hardware producers. It was expected to gain widespread use during 1999, which it also did.

    Here is a an overview of the products I have encountered:


    Microsoft and others. The models connect to USB via a PS/2 adapter. This way, the keyboard can be used with PS/2 or USB - your choice.

    Mice and trackballs

    Some, like Microsoft IntelliMouse, use USB. Some Mac-look products like this (very nice) trackball use USB:


    Some USB models available. However the joystick works very fine being connected to the game port on the sound card, so this interface probably will survive.


    Philips produce very fine USB speakers as also Altec Lansing do. The speakers works without a sound card. However sound needs to be processed, and this works has to be done by the CPU using software. The produced sound is very good but it takes a little power from the CPU, which has to work as sound card as well.

    My own Philips USB-speakers, have the best sound I ever heard. A great digital set! Here you a boxshot of the Philips USB speakers:

    Philips USB speakers


    Many models. For smaller, personal printers USB should be the interface. I encountered problems printing a large photo-job to a Canon BJC 3000 printer using the USB cable. The data amount was to big I think. Swithing to a LPT port the print came out perfect. I was lucky as the printer holds both ports:

    External drives

    Some models like CR-RW and Zip. USB replaces the external models parallel interface. The La Cie company sells an external CD-RW drive, which is connected to the USB port. The drive allegedly behaves like an ordinary EIDE drive and requires no special drivers.

    Modems and ISDN adapters

    Many models. For modems and ISDN USB is the obvious interface to choose.

    Here you see a very elegant little ISDN adapter (DIVA ISDN USB) from Eicon. It gets power from the PC; hence it only holds two connectors. One for the PC and one for the ISDN line:

    Digital cameras

    Works very fine with USB. Should absolutely be preferred. If your camera does not have a USB port, you should a card-reader for USB. It is a very fast and efficient way to move images from the camera to the PC.

    Using the card-reader, the CF-Card becomes a drive. Using Explorer, you can move the images to your harddisk. Here it is a non-permanent disk:

    You may use it as a disk for storage, copying files from the PC to the CF-card as well.

    All modern cameras hold a USB port, which enables you use a cable for direct interface:

    Using a Kodak digital camera, the camera will appear as a drive within Windows ; hence you may access it with Windows Explorer (as above). Using other camera brands like Canon and Nikon, you need special software (ZoomBrowser and NikonView) to access the camera through the USB cable.


    USB works fine with scanners, as already mentioned. However, models with high resolution still use SCSI which still is the best and most stable interface.

    Some scanners made for Macs use the FireWire interface, which has a better bandwidth and gives a more intelligent control than USB does.


    If your PC is full of ISA and PCI adapters, a Ethernet-USB adapter can get you connected to the network. It works, Entegra has one. However, you can get a fine 100 mbit PCI card for less than $25, so I do not expect USB to overrun Ethernet.


    Many hubs to find. Some include COM and LPT ports for conversion to old units.

    We also find COM to USB converting hubs. A box will house four DB9 connectors serving as COM5, 6, 7 and 8. They all connect to the PC via one USB port. This way serial devices can be connected without the IRQ puzzle we often experience nowadays.

    After the driver has been installed, you can connect your serial and parallel devices to the USB hub, which routes the new COM and LPT ports into the PC. The ports appear in Windows like this (please notice COM3, COM4, and LPT2USB1):

    Other USB products

    Adaptec produces a SCSI to USB converter:

    SCSI to USB converter box

    Here you see a TV/Video-grapper unit. Pinnacle PCTV captures TV frames each of 352x288 pixels. The video sequences can be stored on the PC in AVI, MPEG, or REAL format:

    I do not think it works so very well, due to the limited bandwidth of USB. But it shows how versatile the USB interface is.

    New companies

    In the beginning it seemed that smaller, specialized companies come up with interesting USB products. Please check (if they still exist ...):

  • Ariston,
  • La Cie,
  • Aten,
  • Entrega.

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    Learn more

    Read Module 6a about file systems

    Read about chip sets on the motherboard in module 2d

    Read Module 4d about super diskette and MO drives

    Read module 5a about expansion cards, where we evaluate the I/O buses from the port side

    Read module 5b about AGP

    Read module 7a about monitors, and 7b on graphics card

    Read module 7c about sound cards, and 7d on digital sound and music

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