Text Entry Using a Compact Keypad with OSDS
Torsten Felzer, Stephan Rinderknecht · 2014 · Proceedings of the 16th International ACM SIGACCESS Conference on Computers & Accessibility (ASSETS) · doi:10.1145/2661334.2661419
Summary
This demo paper presents OSDS (OnScreenDualScribe), a Windows software tool that enables people with neuromuscular diseases to replace a standard full-size keyboard with a compact 19-key numeric keypad called the DualPad. For people with conditions that cause motor impairment, standard keyboards are problematic because the large travel distances between keys require constant hand repositioning, leading to slow input and frequent errors. The DualPad solves this by using an off-the-shelf numeric keypad (18 keys plus NumLock) held in a rotated orientation so that all keys are reachable with the thumbs without repositioning. Custom keytop stickers indicate each key's function, and the device also replaces a two-button mouse. OSDS intercepts physical keystrokes on the DualPad and translates them into emulated virtual keystrokes, acting as an on-screen interface between the user and whatever application is active. The software provides two text entry methods: a row-column selection mode where the user navigates a two-dimensional virtual keyboard to select characters, and an ambiguous keyboard mode similar to T9 on old mobile phones, where multiple letters share each key and dictionary-based disambiguation resolves the intended word. Both modes include word prediction to reduce the number of keystrokes needed. Beyond text entry, OSDS also supports mouse emulation and system configuration, making it a comprehensive keyboard and mouse replacement solution.
Key findings
The system demonstrates that an inexpensive, off-the-shelf numeric keypad can serve as a viable full computer input replacement for people with neuromuscular diseases. The compact form factor is the key advantage: by keeping all keys within thumb reach in a rotated grip, the system eliminates the hand repositioning that makes standard keyboards slow and error-prone for users with limited motor control. The dual text entry approach — offering both explicit character selection and ambiguous T9-style input with dictionary disambiguation — gives users flexibility to choose the method best suited to their needs and the text being entered. Word prediction further reduces keystroke count. The system operates at the OS level, working with any Windows application without requiring app-specific integration. The authors emphasise real-world applicability, noting that the system has been identified as an effective alternative specifically for users with neuromuscular diseases through prior research. The hardware cost is minimal since it uses standard commercially available keypads with only cosmetic modifications (sticker labels).
Relevance
This work addresses a practical gap in assistive input technology: many people with motor impairments can still use their hands but cannot effectively operate a standard keyboard due to limited range of motion, reduced finger dexterity, or fatigue from large movements. Specialised assistive input devices are often expensive and require custom procurement, whereas OSDS uses commodity hardware costing only a few dollars. For accessibility practitioners and assistive technology specialists, the system illustrates an important design principle — that accessible solutions do not always require specialised hardware; sometimes repurposing common devices with intelligent software can be more practical, affordable, and sustainable. The ambiguous keyboard approach borrowed from mobile phone text entry (T9) shows how interaction paradigms from one domain can be adapted for accessibility in another. Though the paper is a brief demo, OSDS represents a category of low-cost, software-driven assistive solutions that remain relevant as alternatives to expensive commercial assistive technology products.
Tags: text entry · alternative input · keyboard replacement · neuromuscular disease · motor disability · word prediction · assistive technology