A novel text entry system designed based on the ubiquitous 12-button telephone keypad and its adaptation for a soft keypad are presented. This system can be used to enter full text (letters + numbers + special characters) on devices where the number of keys or the keyboard area is limited. Letter-frequency data is used for assigning letters to the positions of a 3x3 matrix on keys, enhancing the entry of the most frequent Letters performed by a double-click. Less frequent letters and characters are entered based on a 3x3 adjacency matrix using an unambiguous, two-keystroke scheme. The same technique is applied to a virtual or soft keyboard layout so letters and characters are entered with taps or slides on an 11-button keypad. Based on the application of Fitts' law, this system is determined to be 67% faster than the QWERTY soft keyboard and 31% faster than the multi-tap text entry system commonly used on cell phones today. The system presented in this paper is implemented and runs on Palm OS PDAs, replacing the built-in QWERTY keyboard and Graffiti recognition systems of these PDAs.

A new technique for designing easily testable PLA's is presented. The salient features of this technique are: 1) low overhead, 2) high fault coverage, 3) simple design, and 4) little or no impact on normal operation of PLA's. This technique consists of the addition of input lines in such a way that, in test mode, any single product line can be activated and its associated circuitry and device can be tested. Using this technique, all multiple stuck-at faults, as well as all multiple extra and multiple missing device faults, are detected.

A technique for modifying networks so that they are capable of self test is presented. The major innovation is partitioning the network into subnetworks with sufficiently few inputs that exhaustive testing of the subnetworks is possible.