It litereally means two completely different architectures, on two physically disconnected computers. Here is a diagram: <a href="https:&#x2F;&#x2F;i.imgur.com&#x2F;Tj0GKbQ.png" rel="nofollow">https:&#x2F;&#x2F;i.imgur.com&#x2F;Tj0GKbQ.png</a><p>Also visible in the diagram is that each side has its own watchdog, both connected to each other. The way this whole thing work is fail safe, so if one computer fails the backup can jump in, and if that fails too the flight controls will either retract or stop in their current position depending on what makes the most sense. It’s also mirrored, so for example if spoiler 2 on the right wing fails and is retracted, spoiler 2 on the left wing will also retract.<p>Here is a description about the flight controls and how pilot input gets passed through to the control surfaces: <a href="http:&#x2F;&#x2F;www.smartcockpit.com&#x2F;docs&#x2F;A320-Flight_Controls.pdf" rel="nofollow">http:&#x2F;&#x2F;www.smartcockpit.com&#x2F;docs&#x2F;A320-Flight_Controls.pdf</a><p>And here is a general overview about the architecture: <a href="http:&#x2F;&#x2F;www.skybrary.aero&#x2F;bookshelf&#x2F;books&#x2F;2313.pdf" rel="nofollow">http:&#x2F;&#x2F;www.skybrary.aero&#x2F;bookshelf&#x2F;books&#x2F;2313.pdf</a>