The Public Switched Telephone Network (PSTN). was designed for high reliability and availability and has achieved an impressive record of service over its history. People today expect continuous telephone service, even in emergencies such as the loss of commercial power or construction cable cuts. The PSTN, however, was not designed for survivability in the face of malicious or catastrophic faults that cause total failure of one of its subscriber-line switching offices. Such a failure could potentially disrupt phone service to thousands of customers for days or weeks, depending on the extent of the damage. Fortunately, modern switching equipment is designed for distribution over a wide geographic area and several subscriber-line architectures are available to address survivability issues. This paper defines the issue of subscriber-line survivability and identifies architectures that improve survivability.
Real‐time computer systems can be difficult to test when their timing characteristics influence the occurrence of problems. Because of this, tools for debugging real‐time systems must account for the interference that they produce in the system they are monitoring. The debugging monitor for the Bell System 1A processor is an example of just such a tool. This paper examines the 1A processor debugging monitor, focusing on the division of the monitor into three separate devices: a hardware monitor that allows autonomous debugging; a resident monitoring program that allows debugging with a minimal interference to normal timing; and a separate mini‐computer monitor that offers extended capability at the expense of unrestricted interference.
El autor examina un documento publicado originalmente en Puebla por el doctor Pedro de Horta, quien fue comisionado por las autoridades del convento de San Jerónimo para evaluar las posibles causas de los ataques epilépticos que sufrían varias monjas de la comunidad. Usando tanto el conocimiento médico y científico que estaba a su disposición, así como lo contenido al respecto en las obras de patriarcas de la Iglesia y teólogos contemporáneos, Horta elaboró un proyecto de tratamiento que buscaba conciliar las posibles explicaciones espirituales y científicas de ese brote epidémico. Desde luego el trabajo de Horta forma parte de la historiografía de la Ilustración y el pensamiento científico y su interacción con la autoridad de la Iglesia y los métodos tradicionales para el tratamiento de enfermedades físicas. El presente estudio busca ubicar la obra de Horta y sus conclusiones en el contexto de la ola de reformas conventuales que se produjo durante la época en que se publicó el documento.
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