How can two PCs communicate without LAN card

How can two PCs running on Windows or Linux can communicate without LAN Card and Modem?

Is this a trick question?

They can through Parallel or Serial connections but they're extremely slow.

Depends what you mean by "communicate" If I was doing it I would use a copy of Kermit on both machines and use a null modem cable. That way you could use a ridiculously high serial port speed.

Be a leetle more specific and maybe we can talk

I smell a cross-post....take a look in the Linux forum!

4 4Life
That is the post how to use Linux to develop a communication system with currently(Spell easily ) available H/W like Mike Speakers webcams etc.

4 this post
Really Some one suggested me about Serial Communication.
I thought we can do it by some tweaking. But knew nothing about it so asked here in forum.
I really mean some serial or || communication (|| is used for parallel )

In terms of speed from best to worst:

1. Ethernet, approx. speed 60-70 Mb/sec if you have 100Mb/s boards
2. USB approx. speed 8 Mb/sec
3. Parallel approx. speed 300 kb/sec
4. Serial approx. speed 150 kb/sec

Ethernet:
You need an ethernet board (twisted-pair) in each PC and a crossover network cable which cuts out the need for a hub or switch. Total cost, 2 boards & cable, about $30 if you shop around.
For the interested the cable looks like this:
URL

USB:
You need obviously a USB port in either PC and you will need to buy a bridge cable, which will put you out a total of about $20.
Havent found a spec for this one, if anyone finds one, post it.

Parallel:
You will need a crossover cable, also known as a Laplink cable.
This will put you out about $15 if you buy.
And for the technically minded:
URL

Serial:
If you're not in hurry then by all means run a serial crossover cable, also about $15.
URL
or
URL
depending on your serial ports size.

But don't forget that getting a hookup between the PCs also entails installing software. If you are running Windoze then this is supported straight off. Check out URL

What do you want to do? Play games, transfer files, share a printer? If you only need to transfer files a parallel Laplink solution would do, as long as you aren't transferring GBs of data.

Also if the distance between the PCs is an issue you will have trouble finding parallel, serial and USB crossover cables longer than 2 meters. For serial cables the longer the cable the slower the speed.

My recommendation would be to go with the ethernet hookup, but if you aren't into installing network boards etc, then go with the USB bridge.

Good luck!

Thanx every one.

Thanx OS Community.