Serial problem with a lot of chips

[The Master]

Hi. Ive made a bunch of circuits that connect to my PC. when i link up 5 or more at the same time they dont work properly. Is this because of the signal strength and how can i fix it?

[The Master]

I think ive found the problem... for now. With 6 circuits connected the signal is fine. The problem im having is because there isnt enough power coming from the PC power supply im using which is strange but i tried another PSU i have and they work fine.

My new plan is to put a small transformer with each board which will free up a pin on the sockets im using so i can have data in *and* out.

I might have to come back to this one when ive got all 14 boards up and running but at least for now the signal is strong enough