Retro1.org codex

CONWAIT                                                     CMS Nucleus command

Use the CONWAIT command to cause a program to wait until all pending terminal
I/O is complete.  The format of the CONWAIT command is:
+----------+------------------------------------------------------------------+
| CONWAIT  |                                                                  |
+----------+------------------------------------------------------------------+

The CONWAIT command synchronizes input and output to the terminal; it ensures
the output console stack is cleared before the program continues execution.
Also, you can ensure a read or write operation is finished before you modify
an I/O buffer.