h6. [[OS SWI Calls]] h6(. » [[OS_UpCall]] h6((. » OS_UpCall 7 h2. OS_UpCall 7 h5. (SWI &33) |_<^{width:4em}. Entry | | |<^. R0 |<^. 7| |<^. R1 |<^. Pointer to poll word (in a global memory area, e.g. the RMA)| |_<^{width:4em}. Exit | | |/2<^. R0 |<^. Preserved (if V flag clear) | |<^. Pointer to error block (if V flag set)| h4. Use The purpose of this call is to inform the TaskWindow module that an open pipe has been closed or deleted h4. Notes It is made by [[PipeFS]] if an open pipe is closed or deleted. It's not available in RISC OS 2. The Task Window module then traps this and objects if any of its tasks are currently waiting for the poll word related to that pipe to become non-zero, by returning an error. This prevents a [[*Shut|*Shut]] command from deleting the workspace which is being accessed by the Task Window, which could potentially cause address exceptions. h4. See also * [[OS_UpCall]] * [[PipeFS]] * [[*Shut|*Shut]]