phantom.ports

provides an overview of phantom ports.

Advanced Pick provides the capability of executing commands in background on special ports called 'phantoms'. Phantom ports do not use a serial port.

They can be used to execute background tasks, running in parallel with the user terminals. Jobs are submitted to a phantom port by the TCL command 'z'. Phantom task activity can be monitored by the TCL command 'list-jobs'. The activity of the phantom ports is supervised by a special phantom, called the 'scheduler', which always run on the last pib of the system.

The number of phantom ports is independent from the number of real ports (i.e., attached to a serial device) or the licensed number of users. The number of phantom ports is defined as follows:

Native Implementation:

The number of phantom ports is fixed (typically 8) and cannot be changed.

AP/DOS

1 phantom port. This number cannot be changed.

Unix Implementations

The number of phantom ports is created at a fixed number, typically 32, but can be changed during the installation procedure to any number. The installation procedure restricts this number to 512, but it can be changed later to a larger number, if required. The TCL command 'config' also allows changing the number of phantoms. The change takes effect the next time the virtual machine is rebooted. The number of phantom ports is described in the configuration file 'pib0' by the statement 'nphts'.

On Unix implementations, the Unix processes running as the Pick phantoms are true daemons, created by the TCL command 'start.ss'.