Dis virtual machine
Encyclopedia
The Dis virtual machine is the execution environment for application code in the Inferno
operating system. Its design is based on a register machine
, closely modeling CISC
-like architectures on which it runs. Code is interpreted
or is just-in-time compiled
into machine code
for the target architecture.
Dis is the target machine for the Limbo programming language.
Dis has memory management
built in. It uses a hybrid of reference counting
and a real-time
garbage collector
for cyclic data.
The instruction set architecture is based on a three-operand memory-to-memory machine. It includes instructions for arithmetic, control flow
, data motion. There are also instructions for creating new process
es, synchronizing and communicating between processes, loading modules of code, and support for higher-level data-types: strings, arrays, lists, and communication channels.
Dis instructions operate on operands of byte (8 bits), word (32 bits), float (64 bits), and big integer (64 bits).
Inferno (operating system)
Inferno is a distributed operating system started at Bell Labs, but is now developed and maintained by Vita Nuova Holdings as free software. Inferno was based on the experience gained with Plan 9 from Bell Labs, and the further research of Bell Labs into operating systems, languages, on-the-fly...
operating system. Its design is based on a register machine
Register machine
In mathematical logic and theoretical computer science a register machine is a generic class of abstract machines used in a manner similar to a Turing machine...
, closely modeling CISC
Complex instruction set computer
A complex instruction set computer , is a computer where single instructions can execute several low-level operations and/or are capable of multi-step operations or addressing modes within single instructions...
-like architectures on which it runs. Code is interpreted
Interpreter (computing)
In computer science, an interpreter normally means a computer program that executes, i.e. performs, instructions written in a programming language...
or is just-in-time compiled
Just-in-time compilation
In computing, just-in-time compilation , also known as dynamic translation, is a method to improve the runtime performance of computer programs. Historically, computer programs had two modes of runtime operation, either interpreted or static compilation...
into machine code
Machine code
Machine code or machine language is a system of impartible instructions executed directly by a computer's central processing unit. Each instruction performs a very specific task, typically either an operation on a unit of data Machine code or machine language is a system of impartible instructions...
for the target architecture.
Dis is the target machine for the Limbo programming language.
Dis has memory management
Memory management
Memory management is the act of managing computer memory. The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and freeing it for reuse when no longer needed. This is critical to the computer system.Several...
built in. It uses a hybrid of reference counting
Reference counting
In computer science, reference counting is a technique of storing the number of references, pointers, or handles to a resource such as an object, block of memory, disk space or other resource...
and a real-time
Real-time computing
In computer science, real-time computing , or reactive computing, is the study of hardware and software systems that are subject to a "real-time constraint"— e.g. operational deadlines from event to system response. Real-time programs must guarantee response within strict time constraints...
garbage collector
Garbage collection (computer science)
In computer science, garbage collection is a form of automatic memory management. The garbage collector, or just collector, attempts to reclaim garbage, or memory occupied by objects that are no longer in use by the program...
for cyclic data.
The instruction set architecture is based on a three-operand memory-to-memory machine. It includes instructions for arithmetic, control flow
Control flow
In computer science, control flow refers to the order in which the individual statements, instructions, or function calls of an imperative or a declarative program are executed or evaluated....
, data motion. There are also instructions for creating new process
Process (computing)
In computing, a process is an instance of a computer program that is being executed. It contains the program code and its current activity. Depending on the operating system , a process may be made up of multiple threads of execution that execute instructions concurrently.A computer program is a...
es, synchronizing and communicating between processes, loading modules of code, and support for higher-level data-types: strings, arrays, lists, and communication channels.
Dis instructions operate on operands of byte (8 bits), word (32 bits), float (64 bits), and big integer (64 bits).
External links
- The design of the Inferno virtual machine
- http://doc.cat-v.org/inferno/4th_edition/dis_VM_design
- http://doc.cat-v.org/inferno/4th_edition/dis_VM_specification