solution Contentsolution Content

HP Product Family - USB 1.0/1.1 and USB 2.0 Overview

What is USB?

Universal Serial Bus (USB) is a port type found on newer computers. There are two versions of USB available: USB 1.0/1.1 and USB 2.0.
Peripherals can connect in a daisy chain, tree, or star configuration, originating from one or more PC I/O ports. They are detected and configured as they are attached (Plug and Play) and can be added or removed without turning off and restarting the computer.
Devices do not have to be connected directly to the computer and can be added and removed without turning off and restarting the computer. Devices can also be attached in any order; for example, attach the keyboard and printer into the computer, then the mouse and joystick into the keyboard, while attaching a modem and scanner through the printer.
  caution:
Always connect an HP all-in-one product directly to the USB port on the back of the computer, or into a powered hub. USB ports on other devices, or on front of some computers might not provide enough power to maintain communication with an all-in-one device.
USB 2.0 is the latest USB standard and started appearing in new products in 2001. The computer and peripheral(s) must be USB 2.0 compliant in order to use this standard.

USB 1.0/1.1

Key specifications are:
  • 1.5 Mbps data transmission rate for 1.0
  • 12 Mbps data transmission rate for 1.1
  • Support for up to 127 devices
  • Hot Plug and Play capability
  • Both isochronous and asynchronous data transfers
  • Cable length of up to 5 meters
  • Built-in power supply/distribution for low-power devices
  • Fully supported only by Windows 98 and Windows 2000

USB 2.0

Key specifications are:
  • Contains all of the features of USB 1.0 and 1.1
  • Fully backward compatible with USB 1.0 and 1.1
  • Available in two versions: USB and Hi-Speed USB
  • Transmission speed of 12-Mbps for USB and 480 Mbps for Hi-Speed USB
  • All peripherals run at their highest rated speed instead of the speed of the slowest peripheral
  • Tested at a higher level than USB 1.0/1.1 so that it is more reliable

USB cables and cable length

The Universal Serial Bus (USB) features one universal plug type for all USB peripheral-to-computer connections.
Figure : USB plug
The USB specification limits the maximum cable length between devices to five meters (just under 16 feet 5 inches).
A powered hub is required for cable lengths over five meters. One powered hub is required for every five additional meters of cable length. Up to five powered hubs can be connected in series, providing a potential of 30 meters (98.4 feet) distance between the USB device and the computer.
note:
Using USB patch cables to extend the length beyond five meters is not recommended or supported.

Is USB faster than parallel?

The speed of a peripheral over the USB port will vary depending on the peripheral type and the amount of USB devices sharing the port. The more devices, the slower the data transfer rate. In general, USB provides a higher data transfer rate than a standard parallel port connection, but a slower rate than a parallel port configured as extended capabilities port (ECP) in the computer BIOS. The real advantage of USB is that it allows multiple devices (up to 127) to be connected over the same port without conflicts.
Connection type and transfer rate
Connection type
Transfer rate (Megabits/second)
Serial port
.92 Mbps
Standard parallel port
.92 Mbps
USB 1.0/1.1
12 Mbps
USB 2.0
12 Mbps
ECP parallel port
24 Mbps
IEEE1394 (Firewire)
400 Mbps
Hi-speed USB 2.0
480 Mbps

How does USB compare to IEEE1394 (Firewire)

The IEEE 1394 standard (sometimes called Firewire) was developed by Apple Computer and is faster than everything except Hi-Speed USB. One firewire port can support up to 63 devices as compared with 127 for USB. Both standards work very well at transferring information from one device to another but USB has gained greater industry acceptance.

How do I identify products that support USB 2.0?

Products that support USB and Hi-Speed USB are identified by different logos than previous versions of USB.
Figure : Old USB 1.0/1.1 logo “not certified”
note:
This is the obsolete version of the USB logo and should not be used
Figure : USB “certified”
Figure : Hi-Speed USB “certified”

USB configuration

Without USB, the computer is capable of attaching only one device to a parallel port. Attaching additional devices required installing additional parallel port cards.
With USB, the computer supports one or two ports, capable of plugging in a device with even more USB ports and then chaining devices without ever opening the computer.
note:
The computer can have a total of 127 USB devices per controller.

Supported Macintosh environments

Macintosh computers, starting with the iMac and the Blue and White G3 Macintosh, have USB support. Older Macintosh computers might have the ability to add a third party USB solution. Use version 8.6 or higher of the Mac OS to connect the HP all-in-one product to a USB port. USB version 1.3.5 or higher is recommended for best performance.

Checking the USB port on a Macintosh computer

  1. From the Apple menu, open the Apple System Profiler
  2. From the Apple System Profiler, click the Devices and Volumes tab. Depending on the number of USB ports available, the HP all-in-one product will show in USB 0 or USB 1.
  3. Directly under the port number, verify the USB Device Extension version. Version 1.3.5 or higher is recommended when using an HP all-in-one.
    note:
    Before installing the HP Officejet G55, G85, or PSC 750 the Apple System Profiler must find the device in the Devices and Volumes tab.

Supported Windows environments

USB is supported in Microsoft Windows versions after Windows 98.
Older operating systems such as Windows 95, NT 4.0, NT3.51, Windows 3.x, and DOS do not provide adequate support for USB. Upgrade the operating system to use USB devices.
note:
Before upgrading the computer operating system, remove any all-in-one product software, and consult the computer manufacturer.
USB will not work if:
  • The operating system is not configured correctly.
  • The version of the operating system does not support USB.
  • USB is disabled in the BIOS.
  • The computer BIOS does not support USB.

Checking the USB port on a Windows computer

note:
In Windows 98 and 2000, USB is already included in the operating system. However, some computer manufacturers ship the computers without setting up USB.
If the Add New Hardware Wizard screen does not appear after connecting the product to the computer USB port, try these steps:
  1. In Windows 98: click Start, Settings, and then Control Panel.
  2. Double-click the System icon.
  3. Click the Device Manager tab.
  4. Click the plus (+) next to Universal Serial Bus Controller.
Figure : The Universal Serial Bus Controller
If a USB host controller and a USB root hub is listed, USB is probably enabled. If you have multiple hubs on the USB chain, try connecting the unit to a different hub or to another USB device. Also, make sure that the cable connections are secure.
If these devices are not listed, refer to the computer documentation or contact the manufacturer for more information on enabling and setting up USB.

USB-tiered architecture

USB uses a tiered-star topology to allow simultaneous attachment of up to 127 devices on the bus at a time. At the root of the tier is the USB Host Controller, which controls all traffic on the bus. The driver for the host controller should be on the system.
Figure : USB-tiered architecture
There are two types of USB Host Controllers:
  • Universal Host Controller Interface (UHCI)
  • Open Host Controller Interface (OHCI)
To check the USB Host Controller type on the system:
  1. Click Start, Settings, and then Control Panel.
  2. Double-click the System icon, and click the Device Manager tab.
  3. Click the plus (+) next to Universal Serial Bus Controller.
  4. When the controller information displays, look for Universal or Open.

More about the tiered architecture

The root hub is part of the computer and Tier 0. Frequently computers come with two USB ports. These ports share the USB bus and controller, allowing for 127 devices total, not per USB port. Likewise, available bandwidth means per bus, not per port. Available USB bandwidth is shared across all USB ports on the computer.
Often a USB hub is attached to the USB root hub on the computer. The hubs usually come with four USB ports. One port can be used to string another USB hub, or the ports can be used to attach USB devices. USB hubs are not the only USB devices with additional USB ports. Many USB devices, such as modems and phones, have additional USB ports.