Is there any PS/2 PCIe card not circuited to USB bridge?

I’m trying to add a third PS/2 device but with current Y cable, I’m only limited to have two PS/2 devices.

How can I expand this limitation to have three PS/2 devices without risking Qubes security?

Are there PS/2 cables that can split to more than 2 female ports?

Are there any PCIe cards that can plug in and play with dom0?

As I understand it, almost all PS/2 PCIe cards are wired to USB bridge that lspci in dom0 would pick up as USB controller, which essentially, makes them USB cards disguise as PS/2.

Can anyone testify that this isn’t true and there is a card that actually works with dom0 right away without complication?

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There would be always complications. PS/2 port dates back before invention of PCI or USB. There used to be a dedicated chip for it (Intel 8042) with two fixed IRQs for each port. A 3rd port was never a standard.

For more information:
http://wiki.osdev.org/"8042"_PS/2_Controller

Recommendation:
If you are using a PCI → USB → PS/2 card, you could identify the PCI device and pass-through it to your sys-usb

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Do you know if those devices actually present the USB bus on the PS/2 connector ? If the connectors really behave only as PS/2 then would their internal USB bus be safe to attach to Dom0, if you can deny other access to it?

I remember having laptops which had combined usb/ps2 ports, and still I have some adapters for using them… and noticed that some cards have an internal connector for extra USB ports, but I never bought one to know if they have the same problem.

Now I am even wondering about the PS/2 on my motherboards…

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