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.
But it is not enough for multiple units, therefore we will need powered hubs.
Here is a an overview of the products I have encountered:
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:
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:
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.
Some scanners made for Macs use the FireWire interface, which has a better bandwidth and gives a more intelligent control than USB does.
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):
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.
In the beginning it seemed that smaller, specialized companies come up with interesting USB products. Please check (if they still exist ...):
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
Copyright (c) 1996-2005 by Michael B. Karbo. www.karbosguide.com.