USB Standard
USB 1.x
USB 1.0 and USB 1.1 introduced the original Low-Speed and Full-Speed USB data modes, laying the foundation for the faster generations that followed.
Overview · Compatibility · Articles
Related: USB Standards · USB 2.0 · USB Connectors
USB 1.x overview
USB 1.0 and USB 1.1 established the original low-bandwidth USB data model before USB 2.0 added High-Speed operation.
| Revisions | USB 1.0 and USB 1.1 |
|---|---|
| Low-Speed | 1.5 Mbps |
| Full-Speed | 12 Mbps |
| Common connectors | USB Standard-A and Standard-B |
| USB-C support | No; USB Type-C was introduced much later |
| Current status | Legacy, with concepts and compatibility carried forward by later USB generations |
Sources: USB-IF USB 2.0 cable and connector document, USB-IF full- and low-speed compliance procedure, and USB-IF USB 2.0 Specification.
USB 1.x compatibility
USB 1.x devices can still work with many newer hosts through legacy signaling, but the connection remains limited to the device's original 1.5 or 12 Mbps speed.
| Connection | What happens | Main limit |
|---|---|---|
| USB 1.x device + USB 1.x host | Operates at the device's Low-Speed or Full-Speed rate | 1.5 Mbps or 12 Mbps device mode |
| USB 1.x device + USB 2.0 host | Normally operates at its original 1.5 Mbps or 12 Mbps rate | The USB 1.x device |
| USB 1.x device + USB 3.x USB-A host | Can use the host's backward-compatible legacy USB path | The USB 1.x device, not the faster USB 3.x port |
| USB 1.x device + USB-C host | Can work through a compatible adapter or hub that exposes legacy USB signaling | Adapter or hub support plus the original device speed |
| USB 2.0 device + USB 1.x host | May fall back to Full-Speed when the device supports that legacy mode | The older host, with a maximum Full-Speed rate of 12 Mbps |
| Newer cable, adapter, or hub + USB 1.x device | May solve the physical connector mismatch but does not upgrade the USB generation | The slowest compatible part of the connection |
Sources: USB-IF full- and low-speed compliance procedure, USB-IF USB 2.0 Specification, and USB-IF USB 2.0 cable and connector document.
USB 1.x articles
Browse guides about early USB compatibility, legacy ports and devices, transfer speeds, adapters, and how USB 1.x relates to later standards.
