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Abstract. It is expected that commodity hardware is becoming less reliable because of the continuously decreasing feature sizes of integrated circuits. Nevertheless, more and more commodity hardware with insufficient error detection is used in critical applications. One possible solution is to detect hardware errors in software using arithmetic AN-codes. These codes detect hardware errors independent of the actual failure modes of the underlying hardware. However, measurements have shown that AN-codes still exhibit large rates of undetected silent data corruptions (SDC). These high rates of undetected SDCs are caused by the insufficient protection of control and data flow through AN-codes. In contrast, ANB-and ANBD-codes promise much higher error detection rates because they also detect errors in control and data flow. We present our encoding compiler that automatically applies either an AN-, ANBor ANBD-code to an application. Our error injections show that AN-, ANB-, and ANBD-codes successfully detect errors and more important that indeed ANB-and ANBD-codes reduce the SDC rate more effectively than AN-codes. The difference between ANBD-and ANB-codes is also visible but less pronounced.

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On time sharing systems for programmed instruction Llekiron. Rechenanl. II (1969). H. 3. S. 143-145 Manuskrtplcingang: 6. 2. 1969. Der programmgesteuerte Rechenautomat als zentrales Glied eines Systems mit großer Speicherkapazität, Multiplexer und vielen angeschlossenen Sichtschirm-Arbeitsplätzen eignet sich unter anderem auch besonders gut für die Realisierung programmierten Unterrichts. Aufbauend auf einem an der Universität Erlangen-Niirnberg realisierten kleinen Versuchssystem wird eine Systemstruktur entwickelt, die sowohl für die Schüler als auch für die Lehrer ein hohes Maß an Bequemlichkeit bietet. Der Rechenautomat wird dabei im wesentlichen dazu benutzt, um zwischen Lehrer und Schüler vermittels eines Systemprogramms und einer einfachen Sprache für Lehrprogramme einen möglichst intensiven Informationsaustausch zu ermöglichen.The programmable computer as the central part of a system with large memory capacity, multiplexing devices and many display terminals is well suited for the realization of programmed instruction. Based on a small experimental system realized at the University of Erlangen a system structure is developed which offers a great amount of convenience to the student and the teacher. With the help of a special operating system and a simple language for instructional programs, the computer is mainly used to provide a satisfactory exchange of information between students and teachers.