element (that is, one that is not marked nondispatchable by
execution. If no task element is marked "nondispatchable," a
In addition to posting a synch lock,
to determine whether
that synch lock, implying that the task is nondispatchable. If this is
the last three bytes of the synch lock to zero.
Tasks may call
the case, each synch lock is inspected and, if any synch lock is posted,
task element for the calling task is marked nondispatchable, its address
is stored in each of the synchronization locks, and dispatching is
resumed for other tasks.
dispatchable. The"dispatcher clears the low-order three tytes of each
of the task's synchronization locks (pointed to in the task element
tefore task execution is resumed).
There are situations when a task requires the services of another task
in order to complete a function. For example,
Both methods use an element,
describes the nature of the request. In general, these elements are
referred to as request
interrupt another task to request an immediate service.
request is described by an ALERT element, the address
specified by the requesting task in a call to
The type cf
of which is
The supervisor responds by giving control to the asynchronous exit
address of the ALERT element that describes the requested service.
The requested task's (that is, the task receiving the request)
asynchronous exit routine responds immediately and may copy the