MPE/iX Glossary of Terms and Acronyms (32650-90887)

52 Chapter1
Glossary of Terms
create other processes. PH capability also allows process suspension,
interprocess communication, and process deletion. Since the proliferation
of processes results in heavy system resource usage, PH capability is
typically restricted to only a few users.
process identification number (PIN) A number assigned to a process by MPE/iX when
the process is created. It is used internally in the process control block
(PCB) table, and during requests for system resources at the console (when
the operator responds to requests by referencing the PIN in the REPLY
command).
process local file descriptor table The table containing the file descriptors for each
process. There is one table per process.
processor-dependent code (PDC) An MPE/iX hardware routine to read and initialize
the I/O paths used for booting or rebooting the system.
processor status word (PSW) Processor status words control the order of instruction
execution and contain various information about the state of a process.
program A sequence of instructions that tells the computer how to perform a
specific task.
program counter (PC) A pointer in memory that points to the instruction to be
executed.
programmable read-only memory (PROM) A PROM chip contains programs that
remain permanently in the computer.
programmatic sessions capability (PS capability) A capability allowing a user to
execute the STARTSESS command and to call the STARTSESS and
ABORTSESS intrinsics.
program-to-program communications (PTOP) A network service that allows
programs residing on different nodes to exchange information with one
another in a master/slave relationship.
prompt The character(s) displayed at the terminal screen indicating that the
system is ready for a command. The MPE/iX command interpreter's
prompt may be changed by the user. The default value is a colon (:).
Subsystems have different prompts.
protocol A set of rules that enables two or more data processing entities to exhange
information. In networks, protocols are the rules and conventions that
govern each layer of network architecture. They define what functions are
to be performed and how messages are to be exchanged.
PUB group A group, created when an account is created, whose files are usually
accessible to all users within the account.
public data network (PDN) A networking service. It fulfills all communications needs
between the host computer and other processes and terminals.
PUB.SYS The public group of the system account. PUB.SYS is where programs and
applications available to all users of the system reside.
purge To delete a permanent file from the system with the PURGE command. The