Binarray is a Boolean logic sandbox, which allows you to create circuits. Using the software, you can gain an understanding of logic gates, and how basic components can be combined to create useful devices. What you build is completely up to you - try building a calculator, or really challenge yourself and build a computer!
This is great.
Theres an error in that system :)
You can't write to the memory since the only one way the wire is going is only allowing signals to go out, but not in.
Source: had the same happen to me.
Yeah that circuit in the screenshot would only allow you to read from the memory, not write to it. It would still be useful if the data is pre-inputted and doesn't need to be changed though, so I wouldn't call it an error.