IBM Common User Access
View on WikipediaCommon User Access (CUA) is a standard for user interfaces to operating systems and computer programs. It was developed by IBM and first published in 1987 as part of their Systems Application Architecture. Used originally in the MVS/ESA, VM/CMS, OS/400, OS/2 and Microsoft Windows operating systems, parts of the CUA standard are now implemented in programs for other operating systems, including variants of Unix. It is also used by Java AWT and Swing.
Motivations and inspirations
[edit]IBM wanted a standard way to interact with text-based user interface software, whether the screen was a dumb terminal connected to a mainframe or a PS/2 with VGA graphics.[1] CUA was a detailed specification and set strict rules about how applications should look and function. Its aim was in part to bring about harmony among DOS applications, which until then had independently implemented different user interfaces.[citation needed]
For example, to open a file:
- In WordPerfect, the command to open a file was F7, 3.
- In Lotus 1-2-3, a file was opened with / (to open the menus), F (for File), R (for Retrieve).
- In Microsoft Word, a file was opened with Esc (to open the menus), T (for Transfer), L (for Load).
- In WordStar, ^ K D (to get to the Opening Menu), followed by D.[2]
- In emacs, a file is opened with Ctrl+x followed by Ctrl+f (for find-file).
- In vi, use Esc to allow commands, then :espace. to open the file browser.
F1 was often the help key (such as Volkswriter (1982)[3]), but in WordPerfect, help was on F3 instead. Some programs used Esc to cancel an action, while some used it to complete one; WordPerfect used it to repeat a character. Some programs used End to go to the end of a line, while some used it to complete filling in a form. Ins sometimes toggled between overtype and inserting characters, but some programs used it for "paste".
Thus every program had to be learned individually and its complete user interface memorised. It was a sign of expertise to have learned the UIs of dozens of applications, since a novice user facing a new program would find their existing knowledge of a similar application either of no use or actively a hindrance to understanding as learned behavior might need to be unlearned for the new application.
The detailed CUA specification, published in December 1987, is 328 pages long. It has similarities to Apple Computer's detailed human interface guidelines (139 pages).[1] The Apple HIG is a detailed book specifying how software for the 1984 Apple Macintosh computer should look and function.[4] When it was first written, the Mac was new, and graphical user interface (GUI) software was a novelty, so Apple took great pains to ensure that programs would conform to a single shared look and feel.[citation needed] CUA had a similar aim, but it faced the more difficult task of trying to impose this retroactively on an existing, thriving but chaotic industry, with the much more ambitious goal of unifying all UI, from personal computers to minicomputers to mainframes; and supporting both character and GUI modes, and both batch and interactive designs. By comparison, the Apple HIG only supported interactive GUI on a standalone personal computer. CUA also attempted to be a more measurable standard than the Apple HIG and had large sections formatted as checklists to measure compliance.
Description
[edit]The CUA contains standards for the operation of elements such as dialog boxes, menus and keyboard shortcuts that have become so influential that they are implemented today by many programmers who have never read the CUA.
Some of these standards can be seen in the operation of Windows itself and DOS-based applications like the MS-DOS 5 full-screen text editor edit.com. CUA hallmarks include:
- All operations can be done with either the mouse or the keyboard;
- If applicable to the page/screen in question F5 provides a refresh function;
- Menus are activated/deactivated with the F10 key;
- Menus are opened by pressing the Alt key plus the underlined letter of the menu name;
- Menu commands that require parameters to proceed are suffixed with an ellipsis ("…");
- Options are requested using secondary windows (often called dialog boxes);
- Options are divided into sections using notebook tabs;
- Navigation within fields in dialog boxes is by cursor key; navigation between fields is by pressing the Tab ↹ key; ⇧ Shift+Tab ↹ moves backwards;
- Dialog boxes have a 'Cancel' button, activated by pressing the Esc key, which discards changes, and an 'OK' button, activated by pressing Return, which accepts changes;
- Applications have online help accessed by a Help menu, which is the last option on the menu bar; context sensitive help can be summoned by F1;
- The first menu is to be called 'File' and contains operations for handling files (new, open, save, save as) as well as quitting the program; the next menu 'Edit' has commands for undo, redo, cut, copy, delete, paste commands;
- The Cut command is ⇧ Shift+Del; Copy is Ctrl+Ins; Paste is ⇧ Shift+Ins;
- The size of a window can be changed by dragging one of the 8 segments of the border.
CUA not only covers DOS applications, but is also the basis for the Windows Consistent User Interface standard (CUI), as well as that for OS/2 applications — both text-mode and the Presentation Manager GUI — and IBM mainframes which conform to the Systems Application Architecture.
CUA was more than just an attempt to rationalise DOS applications — it was part of a larger scheme to bring together, rationalise and harmonise the overall functions of software and hardware across IBM's entire computing range from microcomputers to mainframes.
The third edition of CUA took a radical departure from the first two by introducing the object-oriented workplace. This changed the emphasis of the user's interactions to be the data (documents, pictures, and so on) that the user worked on. The emphasis on applications was removed with the intention of making the computer easier to use by matching users' expectations that they would work on documents using programs (rather than operating programs to work on documents). (See also object-oriented user interface.)
Influence
[edit]CUA strongly influenced the early Microsoft Windows operating system during the period of joint IBM and Microsoft cooperation on OS/2 Presentation Manager. But later releases of IBM's CUA documents were not used for Microsoft products, and so CUA became less significant in the Windows environment. For instance, the Start menu was introduced. Most of the standard keystrokes and basic GUI widgets specified by the CUA remain available in Windows. The well-known combination for closing a window, Alt+F4, stems from CUA.[5]
CUA never had significant impact on the design of Unix terminal (character-mode) applications, which preceded CUA by more than a decade.[citation needed] However, all major Unix GUI environments/toolkits, whether or not based on the X Window System, have featured varying levels of CUA compatibility, with Motif/CDE explicitly featuring it as a design goal. The current major environments, GNOME and KDE, also feature extensive CUA compatibility. The subset of CUA implemented in Microsoft Windows or OSF/Motif is generally considered a de facto standard to be followed by any new Unix GUI environment.
See also
[edit]References
[edit]- IBM, Systems Application Architecture: Common User Access: Panel Design and User Interaction, Document SC26-4351-0, 1987.
- IBM, Systems Application Architecture: Common User Access: Advanced Interface Design Guide, Document SC26-4582-0, 1990.
- IBM, Systems Application Architecture: Common User Access: Basic Interface Design Guide, Document SC26-4583-00 [1], 1992. (Partial archive)
- IBM, Systems Application Architecture: Common User Access: Guide to User Interface Design, Document SC34-4289-00 1991 [2]
- IBM, Systems Application Architecture: Common User Access: Advanced Interface Design Reference, Document SC34-4290-00 1991 [3]
- Object-oriented interface design: IBM common user access guidelines (1st ed.). Que. 1992. ISBN 1565291700.
- ^ a b Alsop, Stewart II (1988-01-18). "Microsoft Windows: Eclectism in UI" (PDF). P.C. Letter. 4 (2): 6–7.
- ^ "WordStar reference manual for release 3.3" (PDF).
- ^ Shuford, Richard S. (May 1983). "Word Tools for the IBM Personal Computer". BYTE. Vol. 8, no. 5. pp. 176–216. Retrieved 19 October 2013.
- ^ Human Interface Guidelines: The Apple Desktop Interface. Addison-Wesley. 1987. ISBN 0-201-17753-6.
- ^ Chen, Raymond (18 September 2018). "Why is Alt+F4 the hotkey for closing a window? Why not Alt+F5 or Alt+F3?". The Old New Thing.
External links
[edit]- "Common User Access – A consistent and usable human-computer interface for the SAA environments". 1998. (1.95 MiB), by Richard E. Berry, IBM Systems Journal, Volume 27, Nº 3, 1988. Citations. This link is down, PDF still available at: https://web.archive.org/web/20070927082756/http://www.research.ibm.com/journal/sj/273/ibmsj2703E.pdf
- "The evolution of the Common User Access Workplace Model" (PDF). Archived (PDF) from the original on September 27, 2007. Retrieved July 12, 2007. (2.68 MiB), by Richard E. Berry, Cliff J. Reeves, IBM Systems Journal, Volume 31, Nº 3, 1992. Citations.
- "The designer's model of the CUA workplace" (PDF). Archived (PDF) from the original on May 30, 2005. Retrieved October 1, 2009. (3.74 MiB), by Richard E. Berry, IBM Systems Journal, Volume 31, Nº 3, 1992. Citations.
- IBM BookManager SAA CUA bookshelf 1992
- CUA Window Emulation for SlickEdit Archived 2020-03-24 at the Wayback Machine - A table of CUA-based hotkeys provided by a SlickEdit mode
IBM Common User Access
View on GrokipediaDevelopment and History
Origins and Motivations
In the mid-1980s, the landscape of personal computing was marked by significant inconsistency in user interfaces, particularly within the MS-DOS ecosystem, where popular applications like WordPerfect and Lotus 1-2-3 employed entirely distinct menu systems, keyboard shortcuts, and command structures, leading to user confusion and prolonged learning curves.[4][5] For instance, Lotus 1-2-3 required users to invoke the file retrieval function via the sequence /FR, while WordPerfect used a separate set of function keys and prompts for similar operations, exacerbating the challenges of switching between programs.[6] This fragmentation extended beyond microcomputers to IBM's broader ecosystem, including mainframe environments like MVS and VM/CMS, as well as dumb terminals and emerging graphical systems such as the PS/2 hardware with VGA displays.[5][2] IBM sought to address these issues through the development of Common User Access (CUA) as a core element of its Systems Application Architecture (SAA) initiative, launched in 1987 to foster a standardized software ecosystem across diverse platforms ranging from mainframes to microcomputers and OS/2.[7][8] Drawing inspiration from Apple's 1987 Human Interface Guidelines, which emphasized consistency and intuitive design, CUA aimed to create a unified user experience that minimized discrepancies between text-based and graphical interfaces.[5] The effort was driven by the need to harmonize human-computer interactions in an era of rapid technological evolution, enabling portability of skills and interfaces across hardware environments like 3270 terminals and PS/2 systems.[2][9] Key motivations for CUA included reducing user training time by promoting learnable, consistent behaviors that allowed seamless transitions between applications and modes, thereby allowing users to focus on tasks rather than relearning interfaces with each new program.[2][5] This approach was intended to support IBM's vision of an "invisible" interface within SAA, where familiarity across platforms—from MVS/ESA mainframes to OS/2 desktops—would decrease errors and enhance overall productivity in enterprise settings.[8][9]Publication and Evolution
IBM published the initial Common User Access (CUA) specification in 1987 as part of its Systems Application Architecture (SAA) initiative. The core document, titled Systems Application Architecture: Common User Access - Panel Design and User Interaction (SC26-4351-0), outlined foundational standards for consistent user interfaces across IBM systems.[2] During this period, IBM collaborated with Microsoft to promote compatibility between CUA and emerging graphical environments, particularly influencing the design of OS/2 Presentation Manager and early Windows interfaces to ensure seamless user experiences across platforms. The guidelines evolved through iterative editions, with updates in 1989 defining basic, intermediate, and advanced dialog types, and the third edition in 1991—known as CUA '91—emphasizing graphical user interfaces and advanced controls for broader adoption in desktop systems.[10][11] The 1992 publication Object-Oriented Interface Design: IBM Common User Access Guidelines introduced an object-oriented workplace model that transitioned interactions from application-centric to data-centric paradigms.[12] Key milestones included the integration of updated CUA standards into IBM's 1992 OS/2 Workplace Shell guide, enhancing productivity tools. CUA principles were incorporated into platforms like AIX starting in the late 1980s to maintain consistency in cross-platform applications. CUA documents structured their content around common elements—such as screen appearance and layout standards—and user interaction techniques, supported by detailed diagrams illustrating UI components, without reliance on equations.[1]Core Principles and Guidelines
Interface Elements and Standards
IBM Common User Access (CUA) established standardized interface elements to ensure uniformity across IBM's diverse computing environments, including mainframes, minicomputers, and personal workstations. Key elements included dialog boxes, which served as secondary windows for user input and options, typically modal to focus attention and modeless to allow multitasking. Pull-down menus appeared from an action bar at the top of primary windows, providing hierarchical access to commands, while cascading menus extended from pull-down selections indicated by right-pointing arrows, enabling deeper navigation without cluttering the main interface. Window management standards emphasized resizable frames with title bars, minimize/maximize controls, and scroll bars, allowing users to arrange multiple windows on the desktop while maintaining visibility of essential controls.[13] CUA differentiated standards for text-based and graphical modes to accommodate varying hardware capabilities, such as character-cell displays on non-programmable terminals (NPTs) and pixel-based graphics on programmable workstations (PWSs). In text-based modes, the entry model used full-screen panels with sequential navigation via function keys, while the text model introduced action bars and pop-up windows within fixed 24x80 character grids to simulate windowing without graphics. Graphical modes, conversely, leveraged pixel resolution for overlapping windows and icons, with the basic graphic model supporting pull-down menus and dialog boxes in environments like OS/2. Information hierarchy was enforced through primary windows, which represented main tasks or object views with dedicated menu bars and client areas, ensuring users focused on core activities before accessing secondary elements like pop-ups.[14][13] Later editions of CUA, particularly the 1991 update (CUA '91), incorporated object-oriented principles through the workplace model, shifting from application-centric interfaces to a unified environment where data and tools appeared as manipulable icons on a virtual desktop. This model treated files, folders, and applications as objects that users could open into primary windows, drag, or link, reducing the need to navigate buried menus and promoting direct manipulation over command-line interactions. The workplace served as a container for all objects, fostering an integrated view of the user's digital environment rather than isolated applications.[14] To minimize cognitive load, CUA mandated consistent metaphors like the workplace or desktop paradigm, where interface elements mimicked familiar office items—such as folders for document storage and trash icons for deletion—to enhance intuitive recognition and affordances, like clickable icons suggesting manipulability. Layout conventions prioritized logical grouping, with action bars at the top, entry fields centered in dialogs, and status areas at the bottom, ensuring predictable scanning patterns across screens. Color schemes followed a restrained palette to aid hierarchy without distraction; for instance, default settings used blue (code 1) for backgrounds, white (7) for unselected text, and turquoise (5) for entry fields, with high-intensity highlighting for cautions and low-intensity for separators. These were configurable but adhered to a 7-color system with intensity and emphasis options like reverse video or underscoring to denote interactivity.[14][15][13]| Element Example | Default Color Code | Description |
|---|---|---|
| Action Bar Unselected Choice | 720 | High-intensity white on blue background for readability. |
| Entry Field | 504 | Low-intensity turquoise with underscore to indicate editability. |
| Caution Text | 620 | High-intensity yellow to draw attention to warnings. |
| Message Text | 220 | High-intensity red for errors or alerts.[15] |