Speed of USB?

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Bill Caroselli

Speed of USB?

Post by Bill Caroselli » Wed Nov 28, 2001 2:46 pm

What is supposed to be the speed of USB?

What are the caviots to achiving that speed?

--
Bill Caroselli -- 1(530) 510-7292
Q-TPS Consulting
QTPS@EarthLink.net

Mario Charest

Re: Speed of USB?

Post by Mario Charest » Wed Nov 28, 2001 3:54 pm

"Bill Caroselli" <qtps@earthlink.net> wrote in message
news:9u2t6r$b2h$1@inn.qnx.com...
What is supposed to be the speed of USB?
USB has two speed slow and very slow ;-)

12 Mbits and 1.5 Mbits

In real life you can expect a maximum of 700-800 Kbytes
What are the caviots to achiving that speed?
The major factor is the device itself.
--
Bill Caroselli -- 1(530) 510-7292
Q-TPS Consulting
QTPS@EarthLink.net


Bill Caroselli

Re: Speed of USB?

Post by Bill Caroselli » Wed Nov 28, 2001 4:02 pm

If there is a slow device on the bus, will it also slow down the faster
device?

--
Bill Caroselli -- 1(530) 510-7292
Q-TPS Consulting
QTPS@EarthLink.net


"Mario Charest" <mcharest@clipzinformatic.com> wrote in message
news:9u310b$dkv$1@inn.qnx.com...
"Bill Caroselli" <qtps@earthlink.net> wrote in message
news:9u2t6r$b2h$1@inn.qnx.com...
What is supposed to be the speed of USB?

USB has two speed slow and very slow ;-)

12 Mbits and 1.5 Mbits

In real life you can expect a maximum of 700-800 Kbytes


What are the caviots to achiving that speed?


The major factor is the device itself.

--
Bill Caroselli -- 1(530) 510-7292
Q-TPS Consulting
QTPS@EarthLink.net




Stephen Munnings

Re: Speed of USB?

Post by Stephen Munnings » Wed Nov 28, 2001 7:10 pm

In article <9u31mn$e5p$1@inn.qnx.com>, qtps@earthlink.net says...
If there is a slow device on the bus, will it also slow down the faster
device?
Only to a certain extent. The devices are "time multiplexed" on the bus,
and the faster device will still communicate at the faster speed during
its time slots. The slower device will still take however long it takes
to communicate at a slower speed.
--
Bill Caroselli -- 1(530) 510-7292
Q-TPS Consulting
QTPS@EarthLink.net


"Mario Charest" <mcharest@clipzinformatic.com> wrote in message
news:9u310b$dkv$1@inn.qnx.com...

"Bill Caroselli" <qtps@earthlink.net> wrote in message
news:9u2t6r$b2h$1@inn.qnx.com...
What is supposed to be the speed of USB?

USB has two speed slow and very slow ;-)

12 Mbits and 1.5 Mbits
USB 2.0 has (will have) a top speed of around 100Mbits
In real life you can expect a maximum of 700-800 Kbytes


What are the caviots to achiving that speed?


The major factor is the device itself.

--
Bill Caroselli -- 1(530) 510-7292
Q-TPS Consulting
QTPS@EarthLink.net







--
Stephen Munnings
Software Developer
Corman Technologies Inc.

Mitchell Schoenbrun

Re: Speed of USB?

Post by Mitchell Schoenbrun » Thu Nov 29, 2001 12:17 am

Previously, Mario Charest wrote in qdn.public.ddk.usb:
USB has two speed slow and very slow ;-)

12 Mbits and 1.5 Mbits
Note that there are two different types of delivery. I
forget their names, but something like reliable (guarenteed
delivery) and real-time (guarenteed throughput).

The former would be for transfering data, such as with a
disk drive, and the later for something like web-cam where
losing data is ok, and getting it in real time is more
important.

Mitchell Schoenbrun --------- maschoen@pobox.com

Guest

Re: Speed of USB?

Post by Guest » Thu Nov 29, 2001 12:52 am

Mitchell Schoenbrun <maschoen@pobox.com> wrote:
Previously, Mario Charest wrote in qdn.public.ddk.usb:

USB has two speed slow and very slow ;-)

12 Mbits and 1.5 Mbits

Note that there are two different types of delivery. I
forget their names, but something like reliable (guarenteed
delivery) and real-time (guarenteed throughput).

The former would be for transfering data, such as with a
disk drive, and the later for something like web-cam where
losing data is ok, and getting it in real time is more
important.
"isochronous" is the web-cam one...

-RK
--
Robert Krten, PARSE Software Devices +1 613 599 8316.
Realtime Systems Architecture, Consulting and Training at www.parse.com
Email my initials at parse dot com.

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