A Universal Serial Bus (USB) system supporting Display Alternate Mode functionality on a USB Type-C adapter is disclosed. In one aspect, a display controller in a display source device can detect a display sink device attached to a display connector of a USB Type-C split adapter and communicate a display data signal to at least three preconfigured display data pins without negotiating a pin assignment with the attached display sink device. In another aspect, the display source device can provide the display data signal to the preconfigured display data pins independent of attachment of the display sink device. By skipping the pin assignment negotiation or providing the display data signal regardless of attachment of the display sink device, it is possible to support Alternate Modes functionality without requiring a Power Delivery (PD) circuit, thus helping to reduce cost, power consumption, and implementation complexity of the display source device.