[Gllug] Crashes (owing to the heatwave?)

[Jon Masters]

On Fri, 8 Aug 2003, Christian Smith wrote:

> S/390 (or zSeries as they are now) are neither PowerPC or POWER4.

Correct. The architectures are very much related but have their
differences between each one. We also have to be clear that when we talk
about PowerPC here we mean the UEA or User Environment Architecture since
the low level Book 4 (and to a lesser extent also book 2 and 3) varies for
each implementation. In fact most different versions of PowerPC today are
implemented in interestingly different ways - e.g. 4xx vs. 7[4]xx.

The original IBM Power architecture and the original instruction set on
the 6xx series were very interesting hypbrids for bridging between archs.

> They have their own architecture that goes back to the origional S/360
> from the sixties, though extended to 64bits now. That is a different
> architecture can be confirmed from the linux kernel assembly.

A good book which everyone should consider owning is by John Irvine and is
called ``Linkers and Loaders'' which features a discussion of the original
IBM executable formats and architecture going back to the 1960s.
I enjoyed reading this book very much indeed.

> Hot plug in mainframes generally works on redundancy of CPUs. CPUs work is
> checkpointed, and a CPU failure results in the last checkpoint being moved
> to another, spare CPU, which picks up the work from that checkpoint.

I am very interested in software implementations of this for regular
Operating Systems as I mentioned many times before - it is one possible
topic for my forthcoming PhD although the more likely topic is related to
real time embedded systems.

Jon.


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