X-Pen? Pen-X? Uni-Pen? Uni-Pen-X? UniX-Pen?

IBM recently surprised pen-based watchers by pulling the wraps off a UNIX-based handwriting recognition system implemented under the X Window system. This introduction was the culmination of work that began at least three years ago.

The Paperlike Interface

The system’s interface, which was developed at IBM’s T.J. Watson Research Center in Yorktown Heights, NY, is called the “Paperlike Interface” (PLI) and will eventually find its way into a 6-pound, 32-bit, notebook-sized, stylus-based computer. The PLI system was introduced as a technical paper/video tape demo in January 1991 at the X Technical Conference in Boston; this was followed by actual demonstrations at the CeBIT conference in Hannover where IBM researchers connected an electronic writing pad to a 386SX-based PS/2 that was running AIX with X Window (X11R4) and Motif.

The actual notebook-sized prototype, which will have a 640×480 monochrome VGA display with 16 gray levels, is expected to be shown before the end of this year.

Even though they admit that AIX (IBM’s UNIX) and X11 (the version of X Window used) are not ideal for small computer systems, IBM researchers nonetheless began development because of the communications and multitasking facilities provided by this environment. On the communication side, wireless LAN technology is a key component.

To develop the prototype, IBM researchers Jim Rhyne, Doris Chow, and Michael Sacks began by extending the OSF/Motif widget set and stripping unessential functions from AIX and X11. They also added TCP/IP, sockets, and NFS — all of which take up less than 2 Mbytes storage space.

X Window Is Not Ideal

Unless IBM researchers continue to come up with some pretty nifty techniques, we are frankly skeptical of this approach. For one thing, X Windows has a reputation for less than lightning-fast performance. While such performance may be acceptable for many desktop applications, pen-based users will need and want response as close to real-time as can be provided. Secondly, UNIX and X Windows are big. Portable pen-based systems will have a small footprint and finite resources. Thirdly, we’re convinced that pen-based computing is a new model that requires new tools and a new way of thinking about computers and computing. This UNIX/X-based approach seems like another retrofitting project.

Don’t get us wrong. We’re champions of UNIX and X as a graphical multitasking environment with a good future. Even if the AIX-X prototype doesn’t become an important pen-based platform, the research coming out of it may lead to major advances for all stylus systems, perhaps in the area of stroke routing, notebook interface design, and device driver technology. With this in mind, we’ll follow up on this project in our next issue with in-depth discussion and analysis.