HeliOS
Encyclopedia
HeliOS was a Unix-like
operating system
for parallel computers developed and sold by Perihelion Software
. It was most commonly used on various Transputer systems, but also supported other architectures. The system provided a micro-kernel that implemented a distributed name space and messaging protocol, through which services were accessed. A POSIX
compatibility library enabled the use of Unix application software, and the system provided most of the usual Unix utilities.
Work on HeliOS began in the autumn of 1986. Its success was limited by the commercial failure of the Transputer, and efforts to move to other architectures met with limited success. Perihelion ceased trading in 1998.
from the University of Bath
, bringing with him some rights to an operating system called TRIPOS
.
MetaComCo secured a contract from Commodore
to work on AmigaOS
, with the AmigaDOS
component being derived from TRIPOS. In 1986, King left MetaComCo to found Perihelion Software
, and began development of a parallel operating system, initially targeted at the INMOS
Transputer series of processors. HeliOS extended TRIPOS' use of a light-weight message passing architecture to networked parallel machines.
HeliOS 1.0 was the first commercial release in the summer of 1988, followed by version 1.1 in autumn 1989, 1.1a in early 1990, 1.2 in December 1990 followed by 1.2.1 and 1.2.2 updates. Version 1.3 was a significant upgrade with numerous utility, library, server and driver improvements. The last commercial release was 1.3.1.
A HeliOS network requires at least one I/O Server node that is able to provide a file system
server, console
server and reset control for the processing nodes. At power on, the HeliOS nucleus is bootstrapped
from the I/O server into the network. Each node is booted using a small first-stage loader that then downloads and initialises the nucleus proper. Once running, a node communicates with its neighbours, booting them in turn, if required.
The HeliOS nucleus is composed of the kernel, libraries, loader service and the processor manager service.
, providing a minimal abstraction above the hardware with most services implemented as non-privileged server processes. It provides memory allocation, process management, message passing and synchronisation primitives.
programming that are shared by the other libraries. The system library provides the basic kernel interface, converting C function calls into messages sent to and from the kernel. It implements an abstraction that allows communication between processes regardless of their location in the network. The server library provides name space support functions for writing HeliOS servers, as described below.
, using a forward slash separating character and textual naming elements.
The name space is managed by the network server, which is started by the I/O server once the nucleus is booted on its first attached node. The network server uses a provided network map to allocate processor names and initialise drivers for hardware devices at specific nodes in the network. The kernel includes a name resolver, and manages a local cache of routes to previously resolved names.
Servers are HeliOS processes that implement the General Server Protocol, typically with the support of the server library. The server protocol is conceptually similar to the Unix VFS
API, and more closely to Plan 9
's 9P
. It requires that servers represent their resources as files, with standardised open/read/write/close-style operations. Similar to facilities such as /proc in Plan 9 and other Unix-like
operating systems, resources such as files, I/O devices, users, and processes are all represented as virtual files in the namespace served by their managing process.
Key servers in HeliOS are the previously mentioned loader, processor manager and network server, together with the session manager, the window server and the file server. Others include the keyboard, mouse, RS232 and Centronics
servers (built into the host I/O server), the null server (like Unix's /dev/null
), and the logger server (like Unix's syslog
).
What is not immediately apparent is that HeliOS extends the notion of Unix pipes into a language called Component Distribution Language (CDL). In CDL, a typical Unix shell pipeline
such as ls | more is called a task force, and is transparently distributed by the Task Force Manager server across the available CPUs. CDL extended traditional Unix syntax with additional operators for bi-directional pipes, sequential and parallel process farm operators, load balancing and resource management.
HeliOS applications can be written using C
, C++
, FORTRAN
and Modula-2
. The POSIX library assists in porting existing Unix software, and provides a familiar environment for programmers. HeliOS does not support occam programs.
CS, Parsytec MultiCluster and SuperCluster, and the Telmat T.Node. The Atari Transputer Workstation
was perhaps the highest profile HeliOS hardware, at least outside academia.
HeliOS ran on T4xx and T8xx, 32 bit Transputers (but not the T2xx 16 bit models) and offered device drivers for various SCSI, Ethernet and graphics hardware from Inmos, Transtech, and others.
In its later versions, HeliOS was ported to the TI TMS320C40 DSP
, and the ARM architecture
.
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
for parallel computers developed and sold by Perihelion Software
Perihelion Software
Perihelion Software was a United Kingdom company founded in 1986 by Dr. Tim King along with a number of colleagues who had all worked together at MetaComCo on AmigaOS and written compilers for both the Amiga and the Atari ST....
. It was most commonly used on various Transputer systems, but also supported other architectures. The system provided a micro-kernel that implemented a distributed name space and messaging protocol, through which services were accessed. A POSIX
POSIX
POSIX , an acronym for "Portable Operating System Interface", is a family of standards specified by the IEEE for maintaining compatibility between operating systems...
compatibility library enabled the use of Unix application software, and the system provided most of the usual Unix utilities.
Work on HeliOS began in the autumn of 1986. Its success was limited by the commercial failure of the Transputer, and efforts to move to other architectures met with limited success. Perihelion ceased trading in 1998.
Development
In the early 1980s, Tim King joined MetaComCoMetaComCo
MetaComCo was a computer systems software company started in 1981 and based in Bristol, England by Peter Mackeonis and Derek Budge.MetaComCo's first product was an MBASIC compatible interpreter for IBM PC's, which was licensed by Peter Mackeonis to Digital Research in 1982, and issued as the...
from the University of Bath
University of Bath
The University of Bath is a campus university located in Bath, United Kingdom. It received its Royal Charter in 1966....
, bringing with him some rights to an operating system called TRIPOS
TRIPOS
TRIPOS is a computer operating system. Development started in 1976 at the Computer Laboratory of Cambridge University and it was headed by Dr. Martin Richards. The first version appeared in January 1978 and it originally ran on a PDP-11. Later it was ported to the Computer Automation LSI4 and the...
.
MetaComCo secured a contract from Commodore
Commodore International
Commodore is the commonly used name for Commodore Business Machines , the U.S.-based home computer manufacturer and electronics manufacturer headquartered in West Chester, Pennsylvania, which also housed Commodore's corporate parent company, Commodore International Limited...
to work on AmigaOS
AmigaOS
AmigaOS is the default native operating system of the Amiga personal computer. It was developed first by Commodore International, and initially introduced in 1985 with the Amiga 1000...
, with the AmigaDOS
AmigaDOS
AmigaDOS is the disk operating system of the AmigaOS, which includes file systems, file and directory manipulation, the command-line interface, and file redirection....
component being derived from TRIPOS. In 1986, King left MetaComCo to found Perihelion Software
Perihelion Software
Perihelion Software was a United Kingdom company founded in 1986 by Dr. Tim King along with a number of colleagues who had all worked together at MetaComCo on AmigaOS and written compilers for both the Amiga and the Atari ST....
, and began development of a parallel operating system, initially targeted at the INMOS
INMOS
Inmos Limited was a British semiconductor company, founded by Iann Barron, with both the head office and the design office at Aztec West in Bristol, it was incorporated in November 1978.- Products :...
Transputer series of processors. HeliOS extended TRIPOS' use of a light-weight message passing architecture to networked parallel machines.
HeliOS 1.0 was the first commercial release in the summer of 1988, followed by version 1.1 in autumn 1989, 1.1a in early 1990, 1.2 in December 1990 followed by 1.2.1 and 1.2.2 updates. Version 1.3 was a significant upgrade with numerous utility, library, server and driver improvements. The last commercial release was 1.3.1.
Kernel and nucleus
HeliOS was designed for a network of multiple nodes, connected by multiple high-bandwidth communications links. Nodes could be dedicated processing nodes, or processors with attached I/O devices. Small systems might consist of a host PC or workstation connected to a set of several processing nodes, while larger systems might have hundreds of processing nodes supported by dedicated nodes for storage, graphics, or user terminals.A HeliOS network requires at least one I/O Server node that is able to provide a file system
File system
A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...
server, console
Virtual console
A virtual console – also known as a virtual terminal – is a conceptual combination of the keyboard and display for a computer user interface. It is a feature of some operating systems such as UnixWare, Linux, and BSD, in which the system console of the computer can be used to switch between...
server and reset control for the processing nodes. At power on, the HeliOS nucleus is bootstrapped
Booting
In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...
from the I/O server into the network. Each node is booted using a small first-stage loader that then downloads and initialises the nucleus proper. Once running, a node communicates with its neighbours, booting them in turn, if required.
The HeliOS nucleus is composed of the kernel, libraries, loader service and the processor manager service.
Kernel
The Helios kernel is effectively a micro-kernelMicrokernel
In computer science, a microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system . These mechanisms include low-level address space management, thread management, and inter-process communication...
, providing a minimal abstraction above the hardware with most services implemented as non-privileged server processes. It provides memory allocation, process management, message passing and synchronisation primitives.
Libraries
The HeliOS nucleus contains three libraries: the system, server and utility libraries. The utility library provides some basic library routines for CC (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
programming that are shared by the other libraries. The system library provides the basic kernel interface, converting C function calls into messages sent to and from the kernel. It implements an abstraction that allows communication between processes regardless of their location in the network. The server library provides name space support functions for writing HeliOS servers, as described below.
Loader and processor manager
The remaining components of the nucleus are the loader and processor manager servers. Once the kernel is loaded, these processes are bootstrapped, and they integrate the newly running node into the HeliOS network.Naming and servers
A key feature in HeliOS is its distributed name system. A HeliOS network implements a single unified name space, with a virtual root node, optional virtual network structuring nodes, nodes for each processor, and sub-processor name spaces provided by services. Names are similar to those in UnixUnix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
, using a forward slash separating character and textual naming elements.
The name space is managed by the network server, which is started by the I/O server once the nucleus is booted on its first attached node. The network server uses a provided network map to allocate processor names and initialise drivers for hardware devices at specific nodes in the network. The kernel includes a name resolver, and manages a local cache of routes to previously resolved names.
Servers are HeliOS processes that implement the General Server Protocol, typically with the support of the server library. The server protocol is conceptually similar to the Unix VFS
Virtual file system
A virtual file system or virtual filesystem switch is an abstraction layer on top of a more concrete file system. The purpose of a VFS is to allow client applications to access different types of concrete file systems in a uniform way...
API, and more closely to Plan 9
Plan 9 from Bell Labs
Plan 9 from Bell Labs is a distributed operating system. It was developed primarily for research purposes as the successor to Unix by the Computing Sciences Research Center at Bell Labs between the mid-1980s and 2002...
's 9P
9P
9P is a network protocol developed for the Plan 9 from Bell Labs distributed operating system as the means of connecting the components of a Plan 9 system. Files are key objects in Plan 9. They represent windows, network connections, processes, and almost anything else available in the operating...
. It requires that servers represent their resources as files, with standardised open/read/write/close-style operations. Similar to facilities such as /proc in Plan 9 and other Unix-like
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
operating systems, resources such as files, I/O devices, users, and processes are all represented as virtual files in the namespace served by their managing process.
Key servers in HeliOS are the previously mentioned loader, processor manager and network server, together with the session manager, the window server and the file server. Others include the keyboard, mouse, RS232 and Centronics
IEEE 1284
IEEE 1284 is a standard that defines bi-directional parallel communications between computers and other devices.-History:In the 1970s, Centronics developed the now-familiar printer parallel port that soon became a de facto standard...
servers (built into the host I/O server), the null server (like Unix's /dev/null
/dev/null
In Unix-like operating systems, /dev/null or the null device is a special file that discards all data written to it and provides no data to any process that reads from it ....
), and the logger server (like Unix's syslog
Syslog
Syslog is a standard for computer data logging. It allows separation of the software that generates messages from the system that stores them and the software that reports and analyzes them...
).
Programming and utilities
From a user's perspective, HeliOS is quite similar to Unix. Most of the usual utility programs are provided, some with extensions to reflect the availability of multiple machines.What is not immediately apparent is that HeliOS extends the notion of Unix pipes into a language called Component Distribution Language (CDL). In CDL, a typical Unix shell pipeline
Pipeline (Unix)
In Unix-like computer operating systems , a pipeline is the original software pipeline: a set of processes chained by their standard streams, so that the output of each process feeds directly as input to the next one. Each connection is implemented by an anonymous pipe...
such as ls | more is called a task force, and is transparently distributed by the Task Force Manager server across the available CPUs. CDL extended traditional Unix syntax with additional operators for bi-directional pipes, sequential and parallel process farm operators, load balancing and resource management.
HeliOS applications can be written using C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
, C++
C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
, FORTRAN
Fortran
Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
and Modula-2
Modula-2
Modula-2 is a computer programming language designed and developed between 1977 and 1980 by Niklaus Wirth at ETH Zurich as a revision of Pascal to serve as the sole programming language for the operating system and application software for the personal workstation Lilith...
. The POSIX library assists in porting existing Unix software, and provides a familiar environment for programmers. HeliOS does not support occam programs.
Hardware
HeliOS was predominantly an operating system for Transputer systems. It supported products from various manufacturers including INMOS' TRAM systems, the MeikoMeiko Scientific
Meiko Scientific Ltd. was a British supercomputer company based in Bristol, founded by members of the design team working on the INMOS transputer microprocessor.-History:...
CS, Parsytec MultiCluster and SuperCluster, and the Telmat T.Node. The Atari Transputer Workstation
Atari Transputer Workstation
The Atari Transputer Workstation was a workstation class computer released by Atari Corporation in the late 1980s. Based on the INMOS transputer, the machine was considerably more powerful than anything available on the market at the time...
was perhaps the highest profile HeliOS hardware, at least outside academia.
HeliOS ran on T4xx and T8xx, 32 bit Transputers (but not the T2xx 16 bit models) and offered device drivers for various SCSI, Ethernet and graphics hardware from Inmos, Transtech, and others.
In its later versions, HeliOS was ported to the TI TMS320C40 DSP
Digital signal processor
A digital signal processor is a specialized microprocessor with an architecture optimized for the fast operational needs of digital signal processing.-Typical characteristics:...
, and the ARM architecture
ARM architecture
ARM is a 32-bit reduced instruction set computer instruction set architecture developed by ARM Holdings. It was named the Advanced RISC Machine, and before that, the Acorn RISC Machine. The ARM architecture is the most widely used 32-bit ISA in numbers produced...
.