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General => The Campus => Topic started by: FORTRANS on March 31, 2013, 07:30:18 AM

Title: USB Question
Post by: FORTRANS on March 31, 2013, 07:30:18 AM
Hi,

   What happens, if anything, if you connect two computers
with an USB cable?  It does not sound like the safest thing
to try, so I thought I would ask.  If something good happens,
is it in the hardware or up to the OS?  If something bad
happens, how bad?

TIA,

Steve
Title: Re: USB Question
Post by: Magnum on March 31, 2013, 07:45:32 AM
I think you can use the cable to transfers files between the two computers.

Title: Re: USB Question
Post by: dedndave on March 31, 2013, 11:34:23 AM
i don't think so - at least, not without drivers
when a USB device is initialized, it selects a mode - serial, USB 1, 2, 3
the computer port reads this and initializes as required
i don't see any way to initialize the port on one computer to tell it to be a "host", if you will
Title: Re: USB Question
Post by: sinsi on March 31, 2013, 01:15:56 PM
You would need some sort of "smart" cable, not just a standard one, that would swap tx/rx lines.
Connecting +5V to +5V might get a bit hairy too...
Title: Re: USB Question
Post by: hutch-- on March 31, 2013, 02:13:28 PM
Sinsi is right, its a NO NO. Stick to TCP/IP with networking, its safe, fast and reliable. Get yourself two 1 gigabit PCI cards, use a twist cable and it will be a kick ass high speed connection, generally faster than either computer. I use a couple of 1gb hubs for a network and its close to being as fast as a twist cable between 2 computers and easily fast enough to back up partitions from one computer to another.
Title: Re: USB Question
Post by: FORTRANS on March 31, 2013, 11:21:39 PM
Hi,

   Thanks for the replies.  More or less what I thought.
The idea came from someone's  locked-up notebook.  And
a bit of a long shot to recover files.

Regards,

Steve N.
Title: Re: USB Question
Post by: Magnum on March 31, 2013, 11:34:05 PM
Have you tried using Linux on a pendrive or CD to access the files ?

Andy
Title: Re: USB Question
Post by: TouEnMasm on April 01, 2013, 02:19:39 AM
Quote
What happens, if anything, if you connect two computers
with an USB cable?

It happens nothing until you create a new connection with windows.
When it is create you can shared your internet connection,copy files from one computer to another and more.
Title: Re: USB Question
Post by: dedndave on April 01, 2013, 02:37:40 AM
did a little googling
what i found was that a "bridged USB cable" may be used
it is USB to USB, but there is an IC in between that provides the bridge logic

as for recovering files from a crashed laptop...
for about $4, you can buy a little adapter that can be used to connect a laptop drive to a desktop SATA port   :t
Title: Re: USB Question
Post by: GoneFishing on April 01, 2013, 04:36:56 AM
Yes, there's a special "bridged" USB cable for the direct connection of two computers (USB DCC).
http://en.kioskea.net/faq/342-connecting-two-computers-with-a-usb-cable

Not so far ago I was also curious about networking over USB.
It would be  really very interesting to connect two PCs with simple USB cable and to see what will happen :P
One article said that it could damage both computers. Didn't try it so don't know for sure
Title: Re: USB Question
Post by: dedndave on April 01, 2013, 04:52:40 AM
yes - the USB interface provides +5V, as sinsi mentioned
it could, conceivably, cause the voltage regulator(s) to go nuts
i would hope they were smart enough to put a diode in there to prevent that - lol
i'll let someone else test it on their machines   :biggrin:
Title: Re: USB Question
Post by: GoneFishing on April 01, 2013, 05:12:08 AM
I think it's a right place to put a question like this:
What is  the "Debug port" feature in USB2.0 (and 3.0?) ?
Title: Re: USB Question
Post by: Tedd on April 01, 2013, 05:27:40 AM
Quote from: FORTRANS on March 31, 2013, 11:21:39 PM
The idea came from someone's  locked-up notebook.  And a bit of a long shot to recover files.

Simple - remove the HDD, it will most likely be SATA, invest $15 in a USB-SATA caddy, connect it up, presto! It's now an external USB drive :t
Title: Re: USB Question
Post by: FORTRANS on April 01, 2013, 06:41:43 AM
Hi,

   Yes, I think the drive is SATA.  Their (HP) manual doesn't
say so, but it says the DVD is SATA.  And yes, I have some
USB IDE external drives.  Just have to go get a SATA box I
guess.  Or have him call HP and see if they know what to do.

   Nice to know about the bridged connection thingy.  Almost
makes sense if you think about it.

Thanks again,

Steve N.
Title: Re: USB Question
Post by: hutch-- on April 01, 2013, 07:24:20 AM
I have a gadget similar to what Tedd mentioned, it plugs into a USB port and you can plug SATA hard disks into it and read them like an external drive. Its only USB2 but it works OK. You really need an external SATA port for high speed data transfer unless you have a much later board that has USB3.
Title: Re: USB Question
Post by: Magnum on April 01, 2013, 08:33:19 AM
My laptop has a nine pin connector and a 15 female connector.

I read where the serial cable can be used to transfer data between computers but I guess it's pretty slow.

Title: Re: USB Question
Post by: dedndave on April 01, 2013, 10:08:56 AM
yes - it would be slow
the 15-pin is for a VGA monitor
Title: Re: USB Question
Post by: farrier on April 01, 2013, 03:12:11 PM
If you have a combination eSata/USB port--as I do on my laptop--you can use something like this:

http://www.amazon.com/Gino-eSATA-Combo-Female-Power/dp/B007PODO3E/ref=pd_sbs_misc_3

provides power for a 2.5" drive and an eSata speed connection.  Much faster than the external USB caddies or cable.

hth,

farrier
Title: Re: USB Question
Post by: sinsi on April 01, 2013, 03:26:07 PM
farrier, it depends on the USB version. I can get speeds the same as eSATA with a USB3-to-SATA adapter.
The problem with eSATA is the need for a separate power supply, although a 3.5" drive with USB3 needs external power (2.5" is OK).
USB2 is 480Mb/s, USB3 is 5Gb/s, eSATA is 6Gb/s (for SATA3). Most laptops still use SATA2 (3Gb/s), so a USB3 drive is actually faster.
Title: Re: USB Question
Post by: ragdog on April 01, 2013, 07:44:55 PM
Hi

Connect to PC´s with usb for data transfer it works
you need a USB-High-Speed-PC-Link-cable

But is slow better is a Lan connection
Title: Re: USB Question
Post by: farrier on April 01, 2013, 11:34:15 PM
sinsi,

Quote from: sinsi on April 01, 2013, 03:26:07 PM
farrier, it depends on the USB version. I can get speeds the same as eSATA with a USB3-to-SATA adapter.

Exactly, USB3 changes the whole story.  But if you're stuck with USB2, and have one of these eSataP--combination USB/eSata--ports, the difference is night and day.  The USB part of the eSataP port provides the 5V power for a 2.5" drive, I haven't tried connecting to a 3.5" drive.

farrier
Title: Re: USB Question
Post by: dedndave on April 01, 2013, 11:49:12 PM
most drives require +5 and +12
USB does not provide +12

that's why i just use an adapter and stick the drive in my desktop by connecting to a SATA port
well - and it's fast, too   :P
Title: Re: USB Question
Post by: dedndave on April 02, 2013, 12:04:53 AM
the adapter i bought is for a 2.5/3.5 SATA drive
i paid ~$4 about 2 years ago, but i see the guy on amazon has it marked up to $20, now - lol
i am sure you could find it for much less by shopping around a little

just a guess - Steve's laptop is older - and it may use an IDE interface
same idea, just know what you need before you buy an adapter
Title: Re: USB Question
Post by: FORTRANS on April 02, 2013, 12:23:45 AM
Hi,

Quote from: Magnum on April 01, 2013, 08:33:19 AM
I read where the serial cable can be used to transfer data between computers but I guess it's pretty slow.

   Well, that depends.  There are different baud rates for one.
And who knows what the software is doing with error correction,
handshaking, or compression.  And what you define as slow.
Anyway I just did a subjective test on a setup I have here, and
it seems a bit less than a tenth of a floppy diskette.  But it is the
only way those two computers communicate.  And thus the
fastest way by default.

Quote from: dedndave on April 02, 2013, 12:04:53 AM
just a guess - Steve's laptop is older - and it may use an IDE interface
same idea, just know what you need before you buy an adapter

   Well, my laptops are older, but the one I was looking at is
someone else's, and is newer.

Cheers,

Steve N.
Title: Re: USB Question
Post by: Magnum on April 02, 2013, 01:57:14 AM
This looks like it covers most  drives.

http://www.starsurplus.com/viewitem.lasso?i=2020
Title: Re: USB Question
Post by: Magnum on April 10, 2013, 07:22:47 AM
This looks fairly fast at 30 Gb/hour.

http://www.walmart.com/ip/Belkin-Easy-Transfer-Cable-for-Windows-Vista/5555531
Title: Re: USB Question
Post by: P1 on April 11, 2013, 04:27:49 AM
Quote from: hutch-- on March 31, 2013, 02:13:28 PM
Sinsi is right, its a NO NO. Stick to TCP/IP with networking, its safe, fast and reliable. Get yourself two 1 gigabit PCI cards, use a twist cable and it will be a kick ass high speed connection, generally faster than either computer. I use a couple of 1gb hubs for a network and its close to being as fast as a twist cable between 2 computers and easily fast enough to back up partitions from one computer to another.
QuoteUSB 2.0 debugging cable/port. Although, setting up USB debugging can take a bit more investment and time, USB might be the only externally exposed port that is capable of debugging on certain laptops and netbooks.
http://blogs.msdn.com/b/usbcoreblog/archive/2010/10/25/setting-up-kernel-debugging-with-usb-2-0.aspx

This looked interesting enough to mention for FORTRANS.

Regards,  P1   8)
Title: Re: USB Question
Post by: FORTRANS on April 11, 2013, 05:04:37 AM
Hi,

   Thank you for the link to a good article.

Regards,

Steve N.
Title: Re: USB Question
Post by: GoneFishing on April 12, 2013, 04:35:19 AM
Thank you , P1!
That article is a perfect answer to my question in this thread either :t