Language-based system

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A language-based system is a type of operating system that uses language features to provide security, instead of or in addition to hardware mechanisms. In such systems, code referred to as the trusted base is responsible for approving programs for execution, assuring they cannot perform operations detrimental to the system's stability without first being detected and dealt with. [1] A very common strategy of guaranteeing that such operations are impossible is to base the system around a high-level language, such as Java, whose design precludes dangerous constructs; many are entirely written in such a language, with only the minimum amount of low-level code being used. [2] Since language-based systems can assure ahead of time that they cannot do things that can damage the system (such as corrupting memory by dereferencing dangling pointers), it is possible for them to avoid expensive address space switches needed by traditional OSes; because of this, microkernels are more popular than traditional systems.[ citation needed ] A more extreme form of this is a high-level language computer architecture, where the trusted base is pushed into hardware, and the entire system is written in a high-level language.

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Kernel (operating system) Core of a computer operating system

The kernel is a computer program at the core of a computer's operating system and generally has complete control over everything in the system. It is the portion of the operating system code that is always resident in memory and facilitates interactions between hardware and software components. A full kernel controls all hardware resources via device drivers, arbitrates conflicts between processes concerning such resources, and optimizes the utilization of common resources e.g. CPU & cache usage, file systems, and network sockets. On most systems, the kernel is one of the first programs loaded on startup. It handles the rest of startup as well as memory, peripherals, and input/output (I/O) requests from software, translating them into data-processing instructions for the central processing unit.

Computer architecture Set of rules describing computer system

In computer engineering, computer architecture is a set of rules and methods that describe the functionality, organization, and implementation of computer systems. The architecture of a system refers to its structure in terms of separately specified components of that system and their interrelationships.

A high-level language computer architecture (HLLCA) is a computer architecture designed to be targeted by a specific high-level programming language (HLL), rather than the architecture being dictated by hardware considerations. It is accordingly also termed language-directed computer design, coined in McKeeman (1967) and primarily used in the 1960s and 1970s. HLLCAs were popular in the 1960s and 1970s, but largely disappeared in the 1980s. This followed the dramatic failure of the Intel 432 (1981) and the emergence of optimizing compilers and reduced instruction set computer (RISC) architectures and RISC-like complex instruction set computer (CISC) architectures, and the later development of just-in-time compilation (JIT) for HLLs. A detailed survey and critique can be found in Ditzel & Patterson (1980).

References

  1. ↑ A Language-Based Approach to Security, Schneider F., Morrissett G. (Cornell University) and Harper R. (Carnegie Mellon University). Informatics: 10 Years Back, 10 Years Ahead. (2000)
  2. ↑ Michael Golm; Meik Felser; Christian Wawerish; Jürgen Kleinöder. "JX - A flexible Java Operating System (poster)". University of Erlangen. Retrieved 2007-04-21.


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