> Mainframes do way more than overnight batch jobs.  A typical mainframe 
> environment will allow for 99.999% uptime.  Handle millions of 
> transactions per day with response times below 5 secs.  A similar 
> environment made out of x86 or x64 hardware, with the required redundancy, 
> clustering and load-balancers required to achieve five-9s uptime (That's 
> less than 25 secs of downtime PER MONTH!) as well has handle the number of 
> transactions at the same speed will probably be as expensive, if not more.

Oh ok, that's all I wondered.  I guess they have different requirements than 
eg Google that decided to take the lots-of-cheap-x86s path.

> That's the main reason banks and airlines (the two industries I'm familiar 
> with) don't change their systems.

Yeh, and if there was some advantage to x86 sytems, it would probably have 
to be quite a large gap to make it worthwhile changing over (which surely 
won't be cheap).

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