Warp wrote:
>   As I understand it (something I remember from the University), the most
> reliable mainframes are quite complicated on both hardware and software
> (well, the operating system) with respect to the CPUs (if there are multiple,
> redundant CPUs which ensure uninterrupted uptime even if a CPU malfunctions).

Yes. This is rather newer than my experience, tho. I never worked personally 
with redundant hardware of that degree of correctness. Most of my bitching 
about lack of correctness in the OS is simple operating system stuff, like 
actually locking files when locked, not leaving temp files around if you 
crash, not starving a write lock just because there are bunches of brief but 
overlapping read locks, etc.  The sort of thing that EINTR is symptomatic of.

>   That's the reason why you can't simply use a PC as a reliable mainframe.
> I don't think Intel processors support anything like this. If a CPU fries,
> you are more or less toast. (Or, in other words, you are going down, no
> matter what, especially if the malfunction happens when the CPU is
> executing some critical kernel code.)

Yep. But you *can* get simulators, if you want to learn how to use the OS 
that the mainframes run and such. (I can't imagine it's strictly POSIX on a 
mainframe, even if they often run some variant of UNIX nowadays.)

-- 
Darren New, San Diego CA, USA (PST)
    C# - a language whose greatest drawback
    is that its best implementation comes
    from a company that doesn't hate Microsoft.

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