Main supervisor

The z/TPF main supervisor provides the resource management usually expected of a control program in direct control of physical facilities. The precise techniques used to accomplish this resource management are topics in z/TPF system structural characteristics. The principal functions performed by the main supervisor are:
  • Work scheduling

    Priority scheduling of input message processing is not done by the z/TPF system. An important processing concept that differentiates the z/TPF system from other operating systems is the way that it handles priorities and dispatches work (that is, an Entry).

    Work already in progress, that is, active Entries, has the highest priority. Scheduling is accomplished by using a limited number of work queues. Priority is determined by processing all of the Entries on a queue before processing the Entries on the next queue. For example, the queue of work that represents completed I/O operations that were requested by active Entries (called the ready list) has higher priority than, and therefore is processed before, the queues of work that represents new messages arriving at a CPC (called the input list).

    In the z/TPF system, work scheduling is called dispatching.

  • I/O interface

    In the z/TPF system, there are no access methods such as those found in z/OS®. Rather, channel programming is integrated into the system support of communication facilities, direct access storage devices (DASD), magnetic tape devices, and unit record devices.

  • Virtual address space management
  • Storage management
  • Interrupt processing
  • Keypointing

    Keypointing is the procedure by which system status is saved in case the system needs to be restarted because of a hardware or software malfunction. In other operating systems, this usually is called checkpointing. Keypoints can be 4 KB or larger in size. See z/TPF Main Supervisor Reference and z/TPF and z/TPFDF System Generation for more information about keypoints.

  • Error recovery.