Information about Helios

HeliOS

Company/ developer:	Perihelion Software
OS family:	Unix-like
Source model:	Proprietary
Latest stable release:	1.3.1 / (date unknown)
Kernel type:	Microkernel
Working state:	Historic

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.^[1] 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.^[2]

Development

In the early 1980s, Tim King joined MetaComCo from Bath University, bringing with him some rights to an operating system called TRIPOS.^[3] 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.

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 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.

Kernel

The Helios kernel is effectively a micro-kernel, 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 C 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 provides by services. Names are similar to those in Unix, 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 Plan9's 9P. It requires that servers represent their resources as files, with standardised open/read/write/close-style operations. Like Plan9, Linux's /proc and other pseudo-filesystems and Unix, files, I/O devices, users, processes and other resources 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), the logger server (like Unix's Syslog), etc.

Programming and Utilities

From a user's perspective, Helios is quite similar to Unix. Most of the usual utility programs were 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 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-direction 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.

Hardware

Helios was predominantly an operating system for Transputer systems. It supported products from various manufacturers including INMOS' TRAM systems, the Meiko 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.

References

Further Reading

• Perihelion Software (1989). The Helios operating system. Prentice Hall International (UK) Ltd. ISBN 0-13-386004-3. 
• Perihelion Software (1991). The Helios parallel operating system. Prentice Hall International (UK) Ltd. ISBN 0-13-381237-5. 

External Links

• Ram Meenakshisundaram's Transputer Home Page

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Greek deities series
Primordial deities
Olympians
Aquatic deities
Chthonic deities
Personified concepts
Other deities
Titans
The Twelve Titans:
Oceanus and Tethys,
Hyperion and Theia,
Coeus and Phoebe,
Cronus and Rhea,
Mnemosyne, Themis,
Crius, Iapetus
Children of Hyperion:
Eos, Helios, Selene
Daughters of Coeus:
Leto and Asteria
Sons of Iapetus:
Atlas, Prometheus,
Epimetheus, Menoetius

In Greek mythology the sun was personified as Helius or Helios (Greek: Ἣλιος). Homer often calls him Titan and Hyperion.

He was a son of the Titans Hyperion and Theia and brother of the goddesses Selene, the moon, and Eos, the dawn. The names of these three were also the common Greek words for sun, moon and dawn.

Helios was imagined as a handsome god crowned with the shining aureole of the sun, who drove a chariot across the sky each day and night. Homer described it as drawn by solar bulls (Iliad xvi.779); later Pindar saw it as drawn by "fire-darting steeds" (Olympian Ode 7.71). Still later, the horses were given fiery names: Pyrios, Aeos, Aethon and Phlegon.

As time passed, Helios was increasingly identified with the god of light, Apollo. The equivalent of Helios in Roman mythology was Sol, Latin for Sun.

Greek mythology

The best known story involving Helius is that of his son Phaëton, who attempted to drive his father's chariot but lost control and set the earth on fire.

Helios was sometimes referred to with the epithet Helios Panoptes ("the all-seeing"). In the story told in the hall of Alcinous in the Odyssey (viii.300ff), Aphrodite, the consort of Hephaestus secretly bedded Ares. All-seeing Helios, lord of the sun, spied on them and told Hephaestus who ensnared the two lovers in nets invisibly fine, to punish them.

In the Odyssey (book XII), Odysseus and his surviving crew landed on Thrinacia, an island sacred to the sun god, whom Circe names Hyperion rather than Helios:

You will now come to the Thrinacian island, and here you will see many herds of cattle and flocks of sheep belonging to the sun-god. There will be seven herds of cattle and seven flocks of sheep, with fifty heads in each flock. They do not breed, nor do they become fewer in number, and they are tended by the goddesses Phaethusa and Lampetia, who are children of the sun-god Hyperion by Neaera. Their mother when she had borne them and had done suckling them sent them to the Thrinacian island, which was a long way off, to live there and look after their father's flocks and herds."

There, the sacred red cattle of the sun were kept. Though Odysseus warned his men not to, they impiously killed and ate some of the cattle. The guardians of the island, Helios' daughters, told their father. Helios, however, appealed to Zeus, who destroyed the ship and killed all the men except for Odysseus.

In one Greek vase painting, Helios appears riding across the sea in the cup of the Delphic tripod which appears to be a solar reference. Athenaeus in Deipnosophistae^[4] related that, at the hour of sunset, Helios climbed into a great golden cup in which he passes from the Hesperides in the farthest west to the land of the Ethiops, with whom he passes the dark hours. While Heracles traveled to Erytheia to retrieve the cattle of Geryon, he crossed the Libyan desert and was so frustrated at the heat that he shot an arrow at Helios, the sun. Helios begged him to stop and Heracles demanded the golden cup which Helios used to sail across the sea every night, from the west to the east. Heracles used this golden cup to reach Erytheia.

By the Oceanid Perse, Helios became the father of Aeëtes, Circe, and Pasiphaë. His other children are Phaethusa ("radiant"), Lampetia ("shining") and Phaëton.

Helios and Apollo

Apollo, as he appears in Homer, is a plague-dealing god with a silver (not golden) bow and has no solar features. "Different names may refer to the same being," Walter Burkert observes (1985:120), "or else they may be consciously equated, as in the case of Apollo and Helios."

The earliest suspected reference to Apollo being identified with the sun titan Helios appears in the surviving fragments of Euripides' play Phaethon in a speech near the end (fr 781 N²), Clymene, Phaethon's mother, laments that Helios has destroyed her child, that Helios whom men rightly call Apollon (the name Apollon here has been often confused with Apollo, the god of light, but in actuality meant "Destroyer"). Since this play, many have referred to Helios as Apollon (sometimes Apollo) but is, in fact, a separate deity.

By Hellenistic times Apollo had become closely connected with the sun in cult. His epithet Phoebus "shining", drawn from Helios, was later also applied by Latin poets to the sun-god Sol.



The identification became a commonplace in philosophic texts and appears in the writing of Parmenides, Empedocles, Plutarch and Crates of Thebes among others, as well as appearing in some Orphic texts. Pseudo-Eratosthenes writes about Orpheus in Catasterismi, section 24:

But having gone down into Hades because of his wife and seeing what sort of things were there, he did not continue to worship Dionysus, because of whom he was famous, but he thought Helios to be the greatest of the gods, Helios whom he also addressed as Apollo(n). Rousing himself each night toward dawn and climbing the mountain called Pangaion, he would await the sun's rising, so that he might see it first. Therefore Dionysus, being angry with him, sent the Bassarides, as Aeschylus the tragedian says; they tore him apart and scattered the limbs.

Dionysus and Asclepius are sometimes also identified with this Apollo Helios.

Classical Latin poets also used Phoebus as a byname for the sun-god, whence come common references in later European poetry to Phoebus and his car ("chariot") as a metaphor for the sun. But in particular instances in myth, Apollo and Helios are distinct. The sun-god, the son of Hyperion, with his sun chariot, though often called Phoebus ("shining") is not called Apollo except in purposeful non-traditional identifications. Roman poets often referred to the sun god as Titan.

Despite these identifications, Apollo was never actually described by the Greek poets driving the chariot of the sun, although it was common practice among Latin poets.

L.R. Farnell^[5] assumed "that sun-worship had once been prevalent and powerful among the people of the pre-Hellenic culture, but that very few of the communities of the later historic period retained it as a potent factor of the state religion." Our largely Attic literary sources tend to give us an unavoidable Athenian bias when we look at ancient Greek religion, and "no Athenian could be expected to worship Helios or Selene," J. Burnet observes,^[6] "but he might think them to be gods, since Helios was the great god of Rhodes and Selene was worshiped at Elis and elsewhere."^[7] Aristophanes' Peace (406-13) contrasts the worship of Helius and Selene with that of the more essentially Greek Twelve Olympians, as the representative gods of the Achaemenid Persians; all the evidence shows that Helius and Selene were minor gods to the Greeks.^[8]

"The island of Rhodes is almost the only place where Helios enjoys an important cult", Burkert asserts (p 174), instancing a spectacular rite in which a quadriga, a chariot drawn by four horses, is driven over a precipice into the sea, with its overtones of the plight of Phaethon noted. There annual gymnastic tournaments were held in his honor. The Colossus of Rhodes was dedicated to him.

Helios also had a significant cult on the acropolis of Corinth on the Greek mainland.

The tension between the mainstream traditional religious veneration of Helios, which had become enriched with ethical values and poetical symbolism in Pindar, Aeschylus and Sophocles,^[9] and the Ionian proto-scientific examination of Helios the Sun, a phenomenon of the study Greeks termed meteora, clashed in the trial of Anaxagoras^[10] ca 450 BCE, a forerunner of the culturally traumatic trial of Socrates for irreligion, in 399.

In Plato's Republic (516B), Helios, the Sun, is the symbolic offspring of the idea of the Good.

Helios Megistos

In Late Antiquity a cult of Helios Megistos ("Great Helios") drew to the image of Helios a number of syncretic elements, which have been analysed in detail by W. Fauth by means of a series of late Greek texts, namely: ^[11] an Orphic Hymn to Helios; the so-called Mithras Liturgy, where Helios rules the elements; spells and incantations invoking Helius among the Greek Magical Papyri; a Hymn to Helios by Proclus; Julian's Oration to Helios, the last stand of official paganism; and an episode in Nonnus' Dionysiaca.

Consorts/Children

1. Aegle
2. Charites
3. Aglaea
4. Euphrosyne
5. Thalia
6. Clymene
7. Heliades
8. Aegiale
9. Aetheria
10. Helia
11. Merope
12. Phoebe
13. Dioxippe
14. Phaeton
15. Merope
16. Neaera
17. Phaethusa
18. Lampetia
19. Rhodus
20. Elektryo
21. Ochimus
22. Cercaphus
23. Macareus
24. Actis
25. Tenages
26. Triopas
27. Candalus
28. Perse
29. Aegea
30. Aeetes
31. Calypso
32. Circe
33. Pasiphae
34. Perses

Epithets

• Terpsimbrotos

See also

• Sun worship
• Sun chariot
• USS Helios (ARB-12)

Notes

References

• Walter Burkert, 1982. Greek Religion.
• Konrad Schauenburg, 1955. Helios: Archäologisch-mythologische Studien über den antiken (Mann)
• Karl Kerenyi. Apollo: The Wind, the Spirit, and the God: Four Studies
• Karl Kerenyi, 1951. The Gods of the Greeks, "The Sun, the Moon and their Family" pp 190-94 et passim.

External links

• Theoi Project, Helios references to the god in classical literature and art
• Greek Mythology Link, Helius summary of Helius myths
• Helios in the Synagogue: Did some ancient Jews worship the sun god?