IBM Common User Access - Motivations and Inspirations

Motivations and Inspirations

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.

Examples:

• 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, it was Ctrl+K+O.
• In emacs, a file was opened with Ctrl+x followed by Ctrl+f (for find-file).

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. F1 was often help, but in WordPerfect, help was on F3 instead. 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 memorized. 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 behaviour might need to be unlearned for the new application.

The detailed CUA specification drew some of its inspiration from Apple Computer's lavishly detailed human interface guidelines. The Apple HIG is a detailed book specifying exactly how software for the Apple Macintosh computer should look and function. 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. 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 single personal computer.