I’m trying to understand whether the Space Shuttle flight control computers, which are sometimes referred to as MISD (Multiple Instruction, Single Data), truly fit this classification.
According to the Wikipedia article on MISD, the Space Shuttle's flight control computer system (System/4 Pi) is cited as an example of MISD architecture:
One prominent example of MISD in practice is the Space Shuttle flight control computers.
However, from my understanding, MISD typically involves multiple processors executing different instructions on the same data stream. The Space Shuttle's computers seem to have been designed for fault tolerance, running identical instructions across multiple nodes to ensure reliability. This seems more like a collection of SISD or SIMD systems working in parallel.
Similarly, modern redundancy systems like MySQL clusters or Apache Cassandra utilise multiple nodes, often with underlying SIMD processors, to process data and maintain consistency. But do these overall configurations constitute a MISD system?
So, my questions are:
- Is the Space Shuttle's System/4 Pi more accurately classified as a redundant SISD system rather than MISD?
- In systems like a MySQL Clusters that implement quorum-based redundancy using SIMD-capable nodes, does this setup constitute an MISD system, or should it be categorised differently under Flynn's Taxonomy?
I'm particularly interested in the theoretical distinctions here, especially since fault-tolerant systems often don't fit neatly into traditional classifications.
