Connecting Two Laptops

Not much. What did you want to happen?

Dueling banjos, if each accesses a suitable source.

The ports on your laptop are set up to be the host of the connection and can't typically function as a device. You would have to go through an intermediate device designed to bridge the two. As noted, ethernet is the natural way to go.

Not much at all. USB IS a hierachical communication system. Two laptops (controller or master) do not care to talk to each other.

Ethernet, on the other hand is designed peer to peer.

So, my question is: why bother with an odd, unnatural gimmick?!?

Not all laptops have ethernet. (or used to)

If they don't have ethernet I bet they have a serial or parallel port, and that can be used for peer-to-peer as well. Either way, if it's that old it probably doesn't have USB.

Using a standard cable with standard USB plugs on each end, when the smoke clears you may have one ready-to-go laptop.

If you are looking to network or do file transfers between the 2 laptops you will need a USB-USB cable with an integral bridge to allow them to talk to each other - or the USB ethernet devices already suggested.

What you are talking about is a USB crossover cable, sometimes called a host to host cable. A USB crossover cable has a chipset built into it which makes it a little more complicated and more costly. A USB crossover is similar to the ethernet crossover explained below except USB uses only 4 wires in the cable. With USB you will need some software to make it work, probably free on the net. This used to be a fairly common thing to do a few years ago to transfer files.

As said in prior posts, ethernet is a more common way to do it since an ethernet port is standard on almost all computers now. Again if you are hooking from one computer to the other, you will need a crossover ethernet cable. (called peer to peer connection) If you connect from one computer into a hub or switch and from that to the other computer, you would use regular straight ethernet cables. You won't need any software to use ethernet.

A crossover cable has it's wires crossed. For instance pin 1 is connected to pin 3; 2 goes to 6 and so forth in that fashion. A straight or normal ethernet cable has pin 1 connected to pin 1; pin 2 to pin 2 for all 8 wires. The internet has a lot of crossover diagrams.

see #3 link

Why bother? Thanks to the SMB (Server Message Block) protocol, a Microsoft invention, it is possible to interconnect computers running OS X, Windows, and Linux over a network just by plugging the machines into a switch or hub, or connecting two of them with a patch cord, or with a crossover cable if they are old.

In another life I connected MS-DOS computers using LapLink and a crossover serial port connector called a "null modem". Unlike USB, which can suffer damage to the port from an improper connection, an incorrect RS-232 connection just didn't work.

Please be careful. A USB-to-USB connection requires a special cable, and a laptop doesn't give you the option of installing a new USB port on a PCI card in case you smoke the port on your motherboard.

Assuming you are referring to a straight connection between the two (type A connector on both ends)

USB is a powered connection. This means the USB port of your laptop is providing 5V and 0V. Due to the small tolerances in this voltage you will overload the USB host chip in one laptop. Next to that you will risk creating a ground loop through the 0V connection.

As stated above by others, the send and receive signals need to be crossed. You will need a special cable for this.

Hi One & All,

You can buy a data USB to USB A cable which has a program cable chip in line like the one talk about by "cuba_pete" which give nice two screen of the host & remote computer are you get a USB to USB cable fashion -- A & B com wire are crossed.

BEN

Ok, I am talking to users and programmers max. It needs some amplification. Any USB port is not a simple data + power supply. There is a long discovery process upon plugging in a new cable. The master port is sensing a real resistance from the user. Then they go thru a multi step process. At the end of which, current is stepwise increased, until the max. value is set appropriate to the class of the use.

No smoke, no muss, no fuss. No smoke. It is built exactly to avoid that. You do the dumb thing, it refuses to work. What I do not recommend is to plug in a power supply on the user end. I am not sure, it would smoke, but I do not recall that case being covered in the protocols.

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Man is inventive. Mindless is infinitely inventive.

You can burn them. You need this usb to usb bridge cable