Specifications

OpenVMS VAX Operating System, Version 5.5-2 SPD 25.01.37
User Environment
Users can access VMS by using the English-like Digi-
tal Command Language (DCL), the command language
for VMS that is supplied with the system. DCL com-
mands take the form of a command name followed by
parameters and qualifiers. DCL commands provide in-
formation about the system, initiate system utilities, and
initiate user programs. VMS prompts users to enter re-
quired DCL parameters, making it easy for novice users
to use.
Users can enter DCL commands at a terminal or in-
clude them in command procedures and can run com-
mand procedures interactively or submit them to a batch
queue for deferred execution.
Information on DCL and VMS Utilities is available
through online Help. Online Help includes summary op-
erational information on all aspects of system operation.
A number of tools and utilities are integrated into the
VMS Operating System. This section briefly describes
some of these tools and utilities.
Text processing — The Extensible VAX Editor (EVE),
one of several text editors supplied by Digital, allows
users to insert, change, and delete text quickly. Written
in the VAX Text Processing Utility Language (VAXTPU),
EVE is a full-screen editor that allows users to scroll
through text on a terminal screen. EVE provides an
EDT-style keypad, allowing users of EDT to transition
to EVE easily.
Mail facility — The Mail facility allows users to send
messages to any other user on the system. Multinode
operation is available if DECnet–VAX is installed and
licensed on each participating node.
Command-level programming — Command-level pro-
gramming allows users to create special files called
command procedures that contain a series of DCL com-
mands. When users execute a command procedure,
the system processes the commands in the command
procedure. Users can also use special DCL commands
to assign symbolic names, evaluate numerical and log-
ical expressions, accept parameters, communicate in-
teractively with the user invoking the command proce-
dure, perform conditional (IF-THEN-ELSE) and branch-
ing (GOTO) logic, and handle error conditions.
User Environment Tailoring — Users can customize the
computing environment with user login command pro-
cedures, shorthand commands, binding of commands
to function keys, and command recall and editing.
Program Development Environment
VMS provides a comprehensive set of tools for devel-
oping programs including editors (for editing source pro-
grams), a linker, a librarian, and a symbolic debugger.
The assembly-level VAX MACRO language is supplied
with VMS.
The VMS Run-Time Library provides string manip-
ulation, I/O routines, I/O conversion, terminal in-
dependent screen handling, date and time format-
ting routines, common mathematical functions, signal-
ing and condition handling, and other general pur-
pose functions. These routines can be called from
programs written in VAX MACRO or from VAX Ada,
VAX BASIC, VAX BLISS-32 Implementation Language,
VAX C, VAX COBOL, VAX DIBOL, VAX FORTRAN,
VAX Pascal, VAX PL/I, and VAX SCAN.
Major VMS languages (including those listed above) ad-
here to the VAX common calling standard, meaning that
routines written in any of these languages can directly
call routines written in any other language. Develop-
ment of applications using multiple languages is simple
and straightforward.
All routines in the Run-Time Library follow the VMS call-
ing standard and condition handling conventions and
most are contained within a shareable image.
At a lower level, programs can call system services di-
rectly for security, event flag, asynchronous system trap,
logical name, record and file I/O, process control, timer,
time conversion, condition handling, lock management,
and memory management services. Again, system ser-
vices use the VMS calling standard and condition han-
dling conventions.
VMS supports execution of non-privileged images cre-
ated on earlier versions of VMS. Recompiling and re-
linking are typically not required.
Some tools available to the VMS programmer are:
Librarian utility — The Librarian utility permits efficient
storage of object modules, macros, Help text, or any
general record-oriented information in central, easily ac-
cessible files. Object module libraries are searched by
the linker when the linker finds a reference it cannot
resolve in one of its input files. Macro libraries are
searched by the assembler when the assembler finds
a macro that is not defined in the input file.
Debugger — The debugger allows users to trace pro-
gram execution as well as display and modify register
contents using the same symbols that are in the source
code.
RMS file utilities — RMS file utilities allow users to an-
alyze the internal structure of an RMS file and to deter-
mine the most appropriate set of parameters for an RMS
file. They can also be used to create, efficiently load,
2