On Sun, 2003-02-16 at 17:32, Mark Darvodelsky wrote: > But the question still does not appear to be answered - why does the > mainframe have to run at such a low clock speed? > > Perhaps someone with some hardware knowledge could explain it? Why can't > the clock be cranked up to be the same speed as the latest Pentium?
This has everything to do with heat dissipation and the media capacity of the processors themselves. Does IBM have the capability to make processors that will run faster, yes. Will they, not without due overcompensation. Look at the history, the AT was running at 6Mhz while every other AT clone manufacturer was running at 8 and 12 - the same went for all of the IBM x86 boxes made. > Most of us mainframe guys understand its inherent advantages, but as > someone has already commented, it often just doesn't wash with management > if a cheap Pentium outperforms a million-dollar mainframe. Convert your favorite CICS app to the Windows world, connect 25000 concurrent user sessions and watch the clock - then come back and tell us how long the Intel box(ES) stayed alive under that realistic load. It boils down to this, at the end of the day the mainframe is still running when the Intel units have had to be rebooted multiple time. This goes without stating that the number of Intel machines it would take to replace that big chunk of iron would cost just as much in hardware and require at least 4 times the support layer to keep the monster alive. TCO rules here. All of this from someone that has spent most of the last 20 years on micro and mid-range machines, interesting perspective huh.
