Editing Domain/OS (section)

==AEGIS==
AEGIS is distinctive mainly for being designed for the networked computer, as distinct from its competitors, which are essentially standalone systems with added network features. The prime examples of this are the [[file system]], which is fully integrated across machines, as opposed to Unix which draws a distinction between file systems on the host system and on others, and the user administration system, which is fundamentally network-based. So basic is this orientation that even a standalone Apollo machine cannot be configured without a [[network card]].

Domain/OS implements functionality derived from both [[UNIX System V|System V]] and early [[Berkeley Software Distribution|BSD Unix]] systems. It improves on AEGIS by providing a core OS upon which the user can install any or all of three [[Universe (Unix)|environments]]: AEGIS, System V Unix, and BSD Unix. This was done in order to provide greater compatibility with Unix; AEGIS version SR9, which immediately preceded Domain/OS (itself numbered SR10) has an optional product called Domain/IX available, which provides a similar capability, but with some drawbacks, principally the fact that core administrative tasks still require AEGIS commands. Also, the SR9 permissions system is not fully compatible with Unix behaviour. Domain/OS provides new administrative commands and a more complex permissions system which can be configured to behave properly under any of the three environments. Domain/OS also provides an improved version of the [[X Window System]], complete with [[Visual User Environment|VUE]] (HP's predecessor to [[Common Desktop Environment|CDE]]), but performance tends to be poor.{{Citation needed|date=July 2022}}

User upgrading from AEGIS SR9 to Domain/OS SR10 was slowed by the fact that many users saw no requirement, by increased disk space requirements, by new and more complex administration tools, by SR10's poorer performance, and by the buggy nature of SR10.0, although later versions are more reliable. However, later HP/Apollo machines (the DN10000, DN2500 and 4xx series workstations) can only run SR10.

Unlike many operating systems of the day, which were written in [[C (programming language)|C]] or [[assembly language]], many Domain/OS components are written in [[Pascal (programming language)|Pascal]]. Compilers for users are available for [[C (programming language)|C]], [[C++]], [[Pascal (programming language)|Pascal]], and [[Fortran]].

All of the distributed administration features of Domain/OS are built around a [[remote procedure call]] system called [[Network Computing System|NCS]] RPC. Though RPC was later end-of-lifed with the operating system, HP contributed RPC to the [[Open Software Foundation]], which incorporated its [[Interface description language|Interface Definition Language (IDL)]] into their [[Distributed Computing Environment|DCE]] product, from which the same technology was later used for [[CORBA]]. One of the original developers{{who|date=October 2022}} went to work for [[Microsoft]], where he developed [[MSRPC]] as a fairly compatible clone which today forms a central component of Windows systems. Traces of the history can be seen in protocol names such as '''nc'''acn_http.{{Citation needed|date=October 2015}}

===User interface===
AEGIS is similar to other workstations of the time, in that it uses a high-resolution graphics screen and mouse to provide a [[Graphical user interface|GUI]] named DM (Display Manager). DM is integrated with the [[operating system|operating system's]] own [[window manager]] known as '''wmgr''' (Window Manager). The DM contains two built-in functions, a [[text editor]] and a transcript, which is a kind of [[command line interface|virtual terminal]]. Additional functions can be added by user programs. One of the unique features of the DM is "universal editing". All text in any of the built-in windows can be edited using the same editing language. This includes the history displayed in a transcript window, although that text is read-only. In addition, the history is unbounded. It starts from the birth of the process to which it is attached, and older history is never deleted. Each transcript is attached to a mini-input window where the process input can be edited using the same editing language used elsewhere.

The AEGIS command interface is similar to [[Unix]], in that it has a [[command line interpreter]] which understands [[pipeline (software)|pipes]], [[redirection (computing)|redirection]], [[Scripting language|scripting]], etc., and invokes other commands as separate programs, but the actual commands themselves are designed to be easier to remember and use than their Unix equivalents, and [[Wildcard character|wildcards]] are expected to be expanded by individual commands rather than by the command line interpreter itself. The user may embed [[environment variable]]s in [[symbolic link]]s, which, for example, allows switching between different versions of Unix by setting the SYSTYPE environment variable accordingly; symbolic links then point to the appropriate versions of the files.