RM A 10 7 23 Get_Immediate (GNAT Reference Manual)

### 6.37 RM A.10.7(23): `Get_Immediate` ¶

> “The `Get_Immediate` procedures should be implemented with unbuffered input. For a device such as a keyboard, input should be available if a key has already been typed, whereas for a disk file, input should always be available except at end of file. For a file associated with a keyboard-like device, any line-editing features of the underlying operating system should be disabled during the execution of `Get_Immediate`.”

Followed on all targets except VxWorks. For VxWorks, there is no way to provide this functionality that does not result in the input buffer being flushed before the `Get_Immediate` call. A special unit `Interfaces.Vxworks.IO` is provided that contains routines to enable this functionality.