(cited from: "AA-EU38A-TE VAXELN V2.0 Users Guide")
For the purposes of this discussion, a dedicated application is one in which the computers are used to solve a specific problem or, possibly, a set of related problems. The term spans a wide range of applications, from "workstations" designed for a particular profession to automated industrial machinery and robots.
In the design of VAXELN, a real-time application is any in which the system's response to external events is critical. Such applications include the typical scientific and industrial data processing situations in which the computer's operation has to be precisely synchronized with machines and special input/output devices.
Traditionally, the design and development of such applications has required expert programmers. The control of external devices usually requires a programmer intimately familiar with the target computer. The precise timing and hardware usage requirements of these applications usually require features not provided in high-level languages, meaning that much of the device-specific code has traditionally been written in assembly language.
Many such applications are best implemented with sets of concurrently executing processes, which have not traditionally been supported by high-level languages. The execution of concurrent processes, along with other constraints, usually requires a host operating system as part of the application, to manage and schedule the processes.
In other words, a traditional application programmer in this area had to be an expert in several fields beside his own profession: the design of real-time systems, programming in assembly language, programming in high-level languages, operating systems, and computer architecture.
The aim of VAXELN is to change this picture, relying mostly on your expertise in your own field rather than on experience with sophisticated programming.
It gives you the following capabilities:
- High-level programming languages
- No operating system "overhead"
- Concurrent programming
- Transparent network support
- File Service
- Program development and debugging with VAX/VMS