Esos aparatos del demonio

• Merom, Conroe y Woodcrest son los nombres de los tres nuevos núcleos procesadores para ordenadores portátiles, de sobremesa y servidores, respectivamente. Se espera que aparezcan en el mercado en 2006. Dicen en Intel que su arquitectura está diseñada desde cero, pero que se han basado en lo mejor de Banias (la del Pentium M) con algunos detalles del Pentium 4 (el bus quad-pumped). Una de las cosas curiosas es que la arquitectura es la misma en todos los tipos y las diferencias son casi sólo de cantidad (más memoria caché para servidores que para sobremesa, por ejemplo). Utilizarán un proceso de fabricación de 65 nm.


• Napa es el nombre de la nueva plataforma para portátiles que sustituirá a Centrilo a principios del año que viene. Calistoga es el chipset de esa plataforma y Yonah el primer procesador que la va a utilizar.

The computer system is very elaborate, having over 250,000 lines of code. [...]

In brief, the hardware reliability is ensured by having four essentially independent identical computer systems. Where possible each sensor also has multiple copies, usually four, and each copy feeds all four of the computer lines. [...]

There is not enough room in the memory of the main line computers for all the programs of ascent, descent, and payload programs in flight, so the memory is loaded about four time from tapes, by the astronauts.

Because of the enormous effort required to replace the software for such an elaborate system, and for checking a new system out, no change has been made to the hardware since the system began about fifteen years ago. The actual hardware is obsolete; for example, the memories are of the old ferrite core type. It is becoming more difficult to find manufacturers to supply such old-fashioned computers reliably and of high quality. Modern computers are very much more reliable, can run much faster, simplifying circuits, and allowing more to be done, and would not require so much loading of memory, for the memories are much larger.

The software is checked very carefully in a bottom-up fashion. First, each new line of code is checked, then sections of code or modules with special functions are verified. The scope is increased step by step until the new changes are incorporated into a complete system and checked. This complete output is considered the final product, newly released. But completely independently there is an independent verification group, that takes an adversary attitude to the software development group, and tests and verifies the software as if it were a customer of the delivered product. There is additional verification in using the new programs in simulators, etc. A discovery of an error during verification testing is considered very serious, and its origin studied very carefully to avoid such mistakes in the future. Such unexpected errors have been found only about six times in all the programming and program changing (for new or altered payloads) that has been done.