Service_USB 1 - Pipe requested exclusively — Exclusive access to pipe requested
| R0 | 1 (reason code) |
| R1 | &80C00 (USB Service call) |
| R2 | Pointer to controller structure |
| R3 | Pointer to device structure |
| R4 | Pointer to endpoint structure |
All registers preserved to pass on else
| R0 | 0 to refuse the exclusive claim or 1 to cause a re-try later |
| R1 | 0 to claim or preserved to pass on. |
| R2, R3, R4 | preserved |
Must be broadcast by an application which wants to get to exclusive access to a shared pipe for operations which may damage the operation of the other applications on the same pipe. If rejected with a 1 result the application may wait for a Service_USB 0 and can afterwards retry to get the control. Note that a pointer to the endpoint structure must be passed because waiting programs are not having a pointer to the pipe structure.