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

28 Chapter1
Glossary of Terms
appropriate action.
error listing A report generated by the system describing the step by step processing of
the job.
error messages Messages describing errors that occur during either an interactive
session or a batch job. The messages are reported to the standard list
device, which is usually a terminal (for a session) or a line printer (for a
job).
escape key A special terminal key that is used in combination with other characters to
give those characters different functions that modify a session or terminal.
The escape key is represented by
ESC or Escape.
escape sequences A sequence of characters beginning with the escape character and
used to control printers, plotters, or the display screen.
EXCLUSIVE access A restriction limiting file access to one user at a time.
execute What the computer does when it carries out the instructions or performs
the routine indicated.
executing state The state of a job/session, displayed when the SHOWJOB command is
executed. Possible states are INTRO, WAIT, EXEC*, EXEC, and SUSP.
execution unit (EU) The part of the CPUcontaining the arithmetic logic unit (ALU) and
the registers. Data is held in registers and manipulated in the ALU.
executive See control program.
execution unit (EU) The part of the CPUcontaining the arithmetic logic unit (ALU) and
the registers. Data is held in registers and manipulated in the ALU.
executor A procedure responsible for executing an operating system command.
explicit dereferencing When the command interpreter encounters an exclamation
point immediately before a variable name, it substitutes the value for the
variable name. Explicit dereferencing may be used in any MPE/iX
command. See implicit dereferencing.
expression A statement consisting of variables, constants, and operators.
extended binary-coded decimal interchange code (EBCDIC) An 8-bit code that is
an extension of binary-coded decimal (BCD) notation. EBCDIC can
represent up to 256 different characters.
extended code segment table (CSTX or XCST) A table containing information about
code segments that come from users' program files and those segments
that are assigned by running a program. CSTX (or XCST) is used in
MPE/iX only in compatibility mode (CM).
extended large addressing MPE/iX can be implemented with either 48-bit or 64-bit
virtual addressing. The 48-bit addressing provides a virtual address space
consisting of 65,000 individual spaces each 4GB (four billion bytes) in size.
This is 65,000 times larger than a typical 32-bit system.
extent A group of one or more contiguous sectors of disk space allocated for a
single file. Extents can be variable length; any number of extents can exist