I saw some videos about CalcNet today and I want to try it sometime with my friends. However, I have two questions.

1. How do I connect 3 calcs?
2. Can I use a USB cord to link a calc (maybe 2 serial cables and 1 USB cord)?

1. You need a arduino board for that, might want to ask Kerm `-`

2. Yes, I do believe you are required to use USB if you lack an arduino (for both calc to calc and calc to computer)

For normal CalcNet too? I thought you only needed an Arduino for gCn...

or, for normal calcnet you can use either `-` it depends on how many calcs you are connecting. for more than 2 calculators you need an arduino. for just 2 calculators, on the other hand, you just need USB

A male-male MiniUSB cord right?

Just.. no.

You only need a bridge (eg Arduino) to interface with gCn. For calculators with direct-USB capability, you can use the calculator as its own bridge over USB.

For local calcnet, you just need every device to share a common bus, for example by splicing several link cables together. There is no capability for local calcnet over USB, because the link layer depends on the two common lines with pull-ups.

You could use an Arduino to act as a "hub" for several I/O cables to come together so that more than two calculators could be connected, but splicing the cables works just as well.

Souvik, in that case you're not using the Arduino for anything other than a patch board, which is a massive, massive waste. To second Tari and correct Qazz, you just splice multiple link cables together such that all the tips are connected, all the rings, and all the grounds. The quick and dirty method would be to cut up link cables and splice them, which means you can have 2N calculators connected with N cables. Cut up 2 cables, and you have four plugs to connect four calculators. Three cables = six calcs, etc. The slower and cleaner method would be to use a bunch of 2.5mm stereo sockets to build a hub of sorts, which would only allow N calculators for N cables.

Ok, so I think I can get this cable thing done. So if I have a simple spliced hub that can connect 4 calculators, can I also just use it to connect 2 or 3 calcs?

Indeed, there's nothing wrong with leaving floating ends in CALCnet, since it relies on pulldowns for transmission. If you go with the splicing route, it might be good to use some three-strand wire to extend some of the cables, too.