Retro1.org codex

NOTREADY                                                 CP Privilege Class:  G

Use the NOTREADY command to change a virtual device to not ready status.  You
cannot specify a Start I/O (SIO) instruction for a virtual device in notready
status.  console.  The format of the NOTREADY command is:
+----------+------------------------------------------------------------------+
| NOTReady | vaddr                                                            |
+----------+------------------------------------------------------------------+
where:

vaddr    is the virtual device address (cuu) of the unit to be removed from
         ready status.


Usage notes:

1.  This command is for use with spooled unit record devices and virtual
    consoles only.

2.  Any I/O operation to the specified device, in progress at the time the
    command is issued, is completed.  On the next Start I/O (SIO) instruction,
    the not ready condition is in effect.