📄 usbfaq.htm
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products needed to accomplish them. An
extension device that looks like a hub to the
USB bus from both sides, but utilizes another
protocol (such as fiber) between the
endpoints of the cable. Each end would
translate USB electrical signaling to or from
a long distance signaling. While this is
possible there are issues regarding packet
protocol and latency that must be considered
to maintain USB compatabilty. </p>
</blockquote>
<p><a name="legacy"></a> <br>
</p>
</li>
<li>Will legacy device suport be in the formal USB
spec? When? <br>
<blockquote>
<p>Legacy support is not a USB spec issue.
There is a class document being developed
that addresses the legacy questions. It is
available now in a 0.9 revision from our
class document download section.. </p>
</blockquote>
<p><a name="xhcicode"></a> <br>
</p>
</li>
<li>Will source code for driving HCI chips be made
available? <br>
<blockquote>
<p>The HCI drivers are supplied as a part of
the OS software stack, obtaining source code
for those drivers would have to be discussed
with the OS vendors. The manufactures of host
controllers may have some test drivers or
production drivers, but again access to the
source code would have to be discussed with
the owners of the code. </p>
</blockquote>
<p><a name="autoattch"></a> <br>
</p>
</li>
<li>When a device is detached it's device driver is
unloaded, if that device is re-inserted, would
it's driver be reloaded? <br>
<blockquote>
<p>Yes, dynamic configuration and
initialization by the OS includes
automaticlly loading and unloading the
drivers as needed. </p>
</blockquote>
<p><a name="fastusb"></a> <br>
</p>
</li>
<li>Are there any plans to increase the bus bandwidth
of USB in the future to 2x, 3x? <br>
<blockquote>
<p>No, USB was designed for a desktop
peripheral interface and has a
performance/cost point for todays
peripherals. A new interface, such as P1394,
for future high speed peripherals may
develop. </p>
</blockquote>
<p><a name="abcon"></a> <br>
</p>
</li>
<li>Can someone clarify the defference and
applications for series "A" and series
"B" connectors? <br>
<blockquote>
<p>The series "A" connector is
intended for all USB devices, is a plug for a
peripheral and a socket for a PC platform. In
most cases a USB cable should be captive
(molded in) to it's peripheral. This saves
connector cost, eliminates incompatabilities
due to power drop in a cable and simplifies
the user connection task. There are some
cases where a captive cable is prohibitive. A
very large heavy device may not be able to
tolerate dangling cables that cannot be
removed and some devices that are only
occasionally connected, but have a useful
function when not connected are good
examples. The series "B" connector
was created for such applications. The 2
connector series are different to prevent
connections that violate the USB architecture
topology. </p>
</blockquote>
<p><a name="rhub"></a> <br>
</p>
</li>
<li>What is the difference between a root hub and
normal hub in terms of hardware and software? <br>
<blockquote>
<p>All hubs are identical from a software
viewpoint(notwithstanding the powered and
unpowered differences). A root hub is simply
the first hub encountered during enumeration.
In many implementations the root hub can be
integrated into the same silicon as the host
controller to save cost. </p>
</blockquote>
<p><a name="specdl"></a> <br>
</p>
</li>
<li>Where can I get a spec? <br>
<blockquote>
<p>The current spec is available for download
from the USB homepage at http://www.usb.org.
Hardcopies will be available at developers
conferences. </p>
</blockquote>
<p><a name="massstor"></a> <br>
</p>
</li>
<li>Is USB a viable Bus for peripherals like CD-R,
tape or hard disk drives? <br>
<blockquote>
<p>The viability depends on the definition of
acceptable performance point. If any of these
devices are for frequent use then I would
want a permanent installation both for
performance and mechanical integration. USB
is not intended to be an inside the box
permanent connection for high speed
peripherals. If the use is occasional or is
for a peripheral that is shared between many
computers, I would think that USB performance
would be more than sufficient. The
convenience of USB and the ubiquitous
connection that USB will bring would outweigh
blazing transfer rates. Still, USB will
provide CD transfer rates up to 4x or 6x
drives(not enough for rewritable drives) and
better transfer rates than the typical LPT
CONNECTED tape drive, floppy drive or
removable hard disk. </p>
</blockquote>
<p><a name="uhcipub"></a> <br>
</p>
</li>
<li>The programming spec for UHCI is not publicly
available. When can one get the UHCI spec? <br>
<blockquote>
<p>Actually the UHCI spec is publicly
available on the Intel web site. The USB web
site has a link to both the OHCI and UHCI
public information sites. Both sites are
linked from an earlier question in this FAQ.</p>
</blockquote>
<p><a name="pdk"></a> <br>
</p>
</li>
<li>How do I get a USB PDK system? <br>
<blockquote>
<p>The PDK was a standard Intel product and
all Intel sales representatives and
distributors should be able to give you
details of price and availability. The need
for that product is vanishing now that
USB systems are available in the retail
market. Intel recently changed the contents
of the PDK as described in this letter to
current PDK owners.</p>
<p><font size="4">Intel Corporation 5200 N.E.
Elam Young Parkway Hillsboro, OR 97124-6497
1-800-628-8686 (Option 1,3,1) Universal
Serial BusPeripheral Developers Kit </font></p>
<p><font size="4">September, 1996 Dear
Universal Serial Bus Developer, </font></p>
<p>Intel’s USB Peripheral Developer Kit
containing the USB Host PC and 930 Evaluation
Kit, has been a huge success. These kits have
been deployed widely across the industry and
in all geographies. Complemented by the USB*
Implementors Forum compliance workshops and
Microsoft*’s beta program, the industry
is well on it’s way to delivering
end-user products. OEMs are already shipping
PC host systems with Intel’s PCI set
silicon and USB connectors. </p>
<p>The Peripheral Developers Kit hardware and
software is changing. The 930 Evaluation Kit
will continue to be available from Intel
(order code USB930EVALKIT). This kit has been
expanded to include the Single Step
Transaction Debugger (SSTD). Intel will
continue to upgrade the evaluation kit as it
is the most popular platform for USB
peripheral developers. Updates to the SSTD
will be available from Intel’s Bulletin
Board System at 916-356-3600 or the World
Wide Web. Contact your local Intel sales
representative for information on how to
register for these updates. The
Microsoft’s WDM beta, which has
equivalent functionality to the Windows* VxD
based stack that shipped with your systems,
is now available from Microsoft. We strongly
suggest you to enroll immediately in their
beta program in order to stay uptodate with
the releases. Microsoft expects you to sign
and return the appropriate NDA to allow them
to send you the current beta release. Please
follow up directly with Microsoft on the
highest urgency. The primary reason for this
transition is to focus your device and device
driver development on the final production
target. </p>
<p>To get a Memphis DDK, send mail to
MEMDDK@microsoft.com and request to receive a
WDM DDK. Also, please include the following
info in your message: First name, last Name,
Title, Company name, Address, City, State,
Zip, Country, phone#, fax#, and internet
address. </p>
<p>Some of the initial USB host PCs were
manufactured with an early stepping (A1) of
the PCI chipset . While the Intel VxD stack
works with these systems, the Microsoft Beta
release works only with systems built using
the later stepping (B0). Intel will be
sending a replacement motherboard at no
charge to purchasers of these early systems.
You should expect to receive the upgrade
hardware in October. Please do NOT contact us
earlier, as there is no immediate
availability of replacement hardware. The
original terms of purchase for warranty and
support for the USB Host system will continue
to be in place. Upon receiving your B0
motherboard, please return your old
motherboard to Intel Corporation, Attn: Mike
Givens, JF2-53, 2111 NE 25th , Hillsboro, OR
97124. </p>
<p>USB enabled PC systems are now available
commercially. If you need additional USB
systems, please order them from the list of
OEMs below or contact your local PC retailer
for price and availability of these systems..
The model numbers for the USB ready systems
are: ⌨️ 快捷键说明
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