USB Requirements - A reference for Designing Servers and Peripherals for the Microsoft® Windows nt® Server Operating...

This section summarizes requirements for Universal Serial Bus. USB is not required in a server system, but if present, it must comply with these requirements.
36 All USB hardware complies with USB 1.0 specifications
All USB hardware present on a server system must comply with the Universal Serial Bus Specification, Version 1.0 or higher, as published by Compaq, Digital Equipment, IBM, Intel, Microsoft, NEC, and Nortel. This ensures that USB hardware has complete Plug and Play capabilities and is implemented in a standard way.
For example, on any system that has USB capabilities, a user must be able to dynamically attach any USB peripheral to any USB connector. The operating system should recognize it automatically, load and initialize the appropriate drivers, and make the device available for use.
37 USB connections use USB icon
The icon can be molded, printed, or affixed as a permanent sticker. Because the location and number of USB ports can be variable, appropriate icons on both ports and cables are important ease-of-use factors. Therefore, USB icons are required for external cables, connecting cables, and connection ports.
Icons can be based on vendor designs, or vendors can use the recommended USB icon defined in Chapter 6 of the USB 1.0 specification as follows:
The USB icon should be molded into the connector and also placed on the product for ease of identifying the USB port. It is recommended that the icon on the product and the one on the plug be adjacent to each other when the plug and receptacle are mated. This icon can be used for both series A and B connector schemes. On the plug, there should be a 0.635‑mm rectangular recessed area around the icon such that there is a perceptible feel of the icon.
38 USB devices and drivers support maximum flexibility of hardware interface options
Device and driver designs should provide maximum flexibility of interface options to allow user-preference coordination by the operating system or other resource managers. This flexibility allows graceful use of multiple simultaneous devices and applications in a dynamic environment.
Specifically, devices with configurations or interfaces that contain isochronous endpoints should not consume any USB bandwidth when the device is first configured. This recommendation can be met by having the zero AltSetting for any interface consume no bandwidth. When the device is put into operation, the device driver should switch the device to an AltSetting that allocates and consumes the required amount of bandwidth. When the device is no longer being used, the driver should return the device to an AltSetting where bandwidth is not consumed.
39 USB host controller meets either OpenHCI or UHCI specification
The host controller must be compliant with the specifications for either OpenHCI (Open Host Controller Interface; published by Compaq, Microsoft, and National Semiconductor) or UHCI (Universal HCI; published by Intel). Hardware manufacturers who design to one of these specifications are not required to provide an additional device driver for their host controller under the Windows NT operating system.
Multiple OpenHCI and UHCI USB controllers are supported concurrently by the operating system.
40 System and devices comply with USB power management requirements
The server system and devices must implement the power descriptor in the USB 1.0 specification. Complete implementation guidelines for OnNow and USB are defined in the “OnNow requirements in the USB Core Specification” section of the article titled “OnNow Power Management and USB” on the web site at http://www.microsoft.com/hwdev/pcfuture/.
41 USB devices meet requirements in the related USB device class specification
Every device must comply with the USB Common Class Specification, Version 1.0 or higher. For any add-on device or peripheral that fits into one of the USB device class definitions, the device must comply with the related USB device class specification. USB class drivers in the operating system are implemented to support compliant devices in each particular class. Class driver extensions and WDM allow IHVs to innovate and differentiate their products while still meeting class compliance in their base operational modes.
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