History
The first version of RISC OS was originally released in 1987 as ''Arthur 1.20''. The next version, , became and was released in April 1989. RISC OS 3.00 was released with the A5000 in 1991, and contained many new features. By 1996, RISC OS had been shipped on over 500,000 systems. Acorn officially halted work on the OS in January 1999, renaming themselves Element 14. In March 1999 a new company, RISCOS Ltd, licensed the rights to develop a desktop version of RISC OS from Element 14, and continued the development of RISC OS 3.8, releasing it as ''RISC OS 4'' in July 1999. Meanwhile, Element 14 had also kept a copy of RISC OS 3.8 in house, which they developed intoSupported hardware
Versions of RISC OS run or have run on the following hardware. RISC OS Open Limited adopted the ' even numbers are stable' version numbering scheme post version 5.14, hence some table entries above include two latest releases – the last stable one and the more recent development one. A special cut down RISC OS Pico (for 16MiB cards and larger) styled to start up like aFeatures
OS core
The OS is single-user and employsFile system
The$
) sign and directories are separated by a full stop (.
). Extensions from foreign file systems are shown using a slash (example.txt
becomes example/txt
). For example, ADFS::HardDisc4.$
is the root of the disc named ''HardDisc4'' using the ,xxx
' to filenames. When using /xtension
Xtension (; foaled 2 February 2007) is a Hong Kong based racehorse. He is one of the nominees of 2010-2011 Hong Kong Horse of the Year
Horse of the Year is the most prestigious honor in Thoroughbred horse racing given by racing organizations in ...
/code>' to the filename under .
A file system can present a file of a given type as a volume of its own, similar to a loop device In Unix-like operating systems, a loop device, vnd (vnode disk), or lofi (loop file interface) is a pseudo-device that makes a computer file accessible as a block device.
Before use, a loop device must be connected to an extant file in the file ...
. The OS refers to this function as an image filing system. This allows transparent handling of archives and similar files, which appear as directories with some special properties. Files inside the image file appear in the hierarchy underneath the parent archive. It is not necessary for the archive to contain the data it refers to: some symbolic link and network share file systems put a reference inside the image file and go elsewhere for the data.
The file system abstraction layer API uses 32-bit file offsets, making the largest single file 4 GiB (minus 1 byte) long. However, prior to RISC OS 5.20 the file system abstraction layer and many RISC OS-native file systems limited support to 31 bits (just under 2 GiB) to avoid dealing with apparently negative file extents when expressed in two's complement
Two's complement is a mathematical operation to reversibly convert a positive binary number into a negative binary number with equivalent (but negative) value, using the binary digit with the greatest place value (the leftmost bit in big- endian ...
notation.
File formats
The OS uses metadata
Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including:
* Descriptive metadata – the descriptive ...
to distinguish file format
A file format is a standard way that information is encoded for storage in a computer file. It specifies how bits are used to encode information in a digital storage medium. File formats may be either proprietary or free.
Some file format ...
s. Some common file formats from other systems are mapped to filetypes by the MimeMap module.
Kernel
The RISC OS kernel is single-tasking and controls handling of interrupt
In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted, ...
s, DMA
DMA may refer to:
Arts
* DMA (magazine), ''DMA'' (magazine), a defunct dance music magazine
* Dallas Museum of Art, an art museum in Texas, US
* Danish Music Awards, an award show held in Denmark
* BT Digital Music Awards, an annual event in the U ...
services, memory allocation and the video display; the cooperative multi-tasking is provided by the WindowManager module.
Desktop
The WIMP
Wimp, WIMP, or Wimps may refer to:
Science and technology
* Weakly interacting massive particle, a hypothetical particle of dark matter
* WIMP (computing), the "window, icon, menu, pointer" paradigm
* WIMP (software bundle), the web stack of Windo ...
interface is based on a stacking window manager
A stacking window manager (also called floating window manager) is a window manager that draws and allows windows to overlap, without using a compositing algorithm. All window managers that allow the overlapping of windows but are not compositing ...
and incorporates three mouse buttons (named ''Select'', ''Menu'' and ''Adjust''), context-sensitive menus, window order control (i.e. send to back) and dynamic window focus (a window can have input focus at any position on the stack). The icon bar (Dock
A dock (from Dutch ''dok'') is the area of water between or next to one or a group of human-made structures that are involved in the handling of boats or ships (usually on or near a shore) or such structures themselves. The exact meaning vari ...
) holds icons which represent mounted disc drives, RAM discs, running applications, system utilities and docked: files, directories or inactive applications. These icons have context-sensitive menus and support drag-and-drop
In computer graphical user interfaces, drag and drop is a pointing device gesture in which the user selects a virtual object by "grabbing" it and dragging it to a different location or onto another virtual object. In general, it can be used to ...
operation. They represent the running application as a whole, irrespective of whether it has open windows.
The GUI functions on the concept of files. The Filer, a spatial file manager, displays the contents of a disc. Applications are run from the Filer view and files can be dragged to the Filer view from applications to perform saves, rather than opening a separate 'Save' dialog box where the user must navigate to a location already visible in the Finder. In addition, files can be directly transferred between applications by dragging a save icon into another application's window.
Application directories are used to store applications. The OS differentiates them from normal directories through the use of an exclamation mark (also called a ''pling'' or ''shriek'') prefix. Double-clicking on such a directory launches the application rather than opening the directory. The application's executable files and resources are contained within the directory, but normally they remain hidden from the user. Because applications are self-contained, this allows drag-and-drop installing and removing.
The ''Style Guide'' encourages a consistent look and feel
In software design, the look and feel of a graphical user interface comprises aspects of its design, including elements such as colors, shapes, layout, and typefaces (the "look"), as well as the behavior of dynamic elements such as buttons, box ...
across applications. This was introduced in and specifies application appearance and behaviour. Acorn's own main bundled applications were not updated to comply with the guide until 's ''Select'' release in 2001.
Font manager
RISC OS was the first operating system to provide scalable anti-aliased fonts. Anti-aliased fonts were already familiar from Arthur, and their presence in RISC OS was confirmed in an early 1989 preview, featuring in the final RISC OS 2 product, launched in April 1989.
A new version of the font manager employing "new-style outline fonts" was made available after the release of RISC OS, offering full support for the printing of scalable fonts, and was provided with Acorn Desktop Publisher. It was also made available separately and bundled with other applications. This outline font manager provides support for the rendering of font outlines to bitmaps for screen and printer use, employing anti-aliasing for on-screen fonts, utilising sub-pixel anti-aliasing and caching for small font sizes. At the time of the introduction of Acorn's outline font manager, the developers of rival desktop systems were either contemplating or promising outline font support for still-unreleased products such as Macintosh System 7
System 7, codenamed "Big Bang", and also known as Mac OS 7, is a graphical user interface-based operating system for Macintosh computers and is part of the classic Mac OS series of operating systems. It was introduced on May 13, 1991, by Apple C ...
and OS/2
OS/2 (Operating System/2) is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci. As a result of a feud between the two companies over how to position OS/2 r ...
version 2.
Since 1994, in RISC OS 3.5, it has been possible to use an outline anti-aliased font in the WindowManager for UI elements, rather than the bitmap system font from previous versions. RISC OS 4 does not support Unicode
Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, ...
but "RISC OS 5 provides a Unicode Font Manager which is able to display Unicode characters and accept text in UTF-8
UTF-8 is a variable-length character encoding used for electronic communication. Defined by the Unicode Standard, the name is derived from ''Unicode'' (or ''Universal Coded Character Set'') ''Transformation Format 8-bit''.
UTF-8 is capable of e ...
, UTF-16 and UTF-32. Other parts of the RISC OS kernel and core modules support text described in UTF-8."
Support for the characters of RISC OS (and some other historic computers) was added to Unicode
Unicode, formally The Unicode Standard,The formal version reference is is an information technology standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard, ...
13.0 (in 2020).
Bundled applications
is available in several distributions, all of which include a small standard set of desktop applications, but some of which also include a much wider set of useful programs. Some of those richer distributions are freely available, some are paid for.
Backward compatibility
Limited software portability
A computer program is said to be portable if there is very low effort required to make it run on different platforms. The pre-requirement for portability is the generalized abstraction between the application logic and system interfaces. When ...
exists with subsequent versions of the OS and hardware. Single-tasking BBC BASIC applications often require only trivial changes, if any. Successive OS upgrades have raised more serious issues of backward compatibility
Backward compatibility (sometimes known as backwards compatibility) is a property of an operating system, product, or technology that allows for interoperability with an older legacy system, or with input designed for such a system, especiall ...
for desktop applications and games. Applications still being maintained by their author(s) or others have sometimes historically been amended to provide compatibility.
The introduction of the RiscPC in 1994 and its later StrongARM upgrade raised issues of incompatible code sequences and proprietary squeezing (data compression
In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compressio ...
). Patch
Patch or Patches may refer to:
Arts, entertainment and media
* Patch Johnson, a fictional character from ''Days of Our Lives''
* Patch (''My Little Pony''), a toy
* "Patches" (Dickey Lee song), 1962
* "Patches" (Chairmen of the Board song ...
ing of applications for the StrongARM was facilitated and Acorn's ''UnsqueezeAIF'' software unsqueezed images according to their AIF header
In computer programming, the Arm Image Format (AIF) is an object file format used primarily for software intended to run on ARM microprocessors. It was introduced by Acorn Computers for use with their Archimedes computer. It can optionally facili ...
. The incompatibilities prompted release by ''The ARM Club'' of its ''Game On!'' and ''StrongGuard'' software. They allowed some formerly incompatible software to run on new and upgraded systems. The version of the OS for the A9home prevented the running of software without an AIF header (in accord with Application Note 295) to stop "trashing the desktop".
The Iyonix PC
The Iyonix PC was an Acorn-clone personal computer sold by Castle Technology and Iyonix Ltd between 2002 and 2008. According to news site ''Slashdot'', it was the first personal computer to use Intel's XScale processor. It ran .
History
T ...
() and A9home (custom ) saw further software incompatibility because of the deprecated addressing modes. Most applications under active development have since been rewritten. Static code analysis to detect -only sequences can be undertaken using ''ARMalyser''. Its output can be helpful in making 32-bit versions of older applications for which the source code is unavailable. Some older 26-bit software can be run without modification using the Aemulor emulator.
Additional incompatibilities were introduced with newer ARM core
This is a list of central processing units based on the ARM family of instruction sets designed by ARM Ltd. and third parties, sorted by version of the ARM instruction set, release and name. In 2005, ARM provided a summary of the numerous vendor ...
s, such as ARMv7 in the BeagleBoard and ARMv8 in the . This includes changes to unaligned memory access in ARMv6/v7 and removal of the SWP instructions in ARMv8.
See also
* Acorn C/C++
* ArtWorks
A work of art, artwork, art piece, piece of art or art object is an artistic creation of aesthetic value. Except for "work of art", which may be used of any work regarded as art in its widest sense, including works from literatur ...
* Drobe
''Drobe'' (also referred to as ''Drobe Launchpad'') was a computing news web site with a focus on the operating system. Its archived material was retained online, curated by editor Chris Williams until late 2020.
History
''Drobe'' was found ...
* ROX Desktop
The ROX Desktop is a graphical desktop environment for the X Window System. It is based on the ROX-Filer which is a drag and drop spatial file manager. It is free software released under the GNU General Public License. The environment was i ...
, a graphical desktop environment for the X Window System, inspired by the user interface of RISC OS
* Sibelius (scorewriter), originally an application for RISC OS, rewritten for Windows in 1998
* RISC OS character set
References
External links
* RISC OS Open
{{Operating system
Acorn operating systems
ARM operating systems
Desktop environments
Free software operating systems
Software using the Apache license
Window-based operating systems
1987 software