🚀 go-pugleaf

Douglas W. Jones,201H MLH,3193350740,3193382879 wrote:
> 
> From article <33B8C6...@pce.net>, by Micheal Peters <mich...@pce.net>:
> > Rashid J Al-Ali wrote:
> >>
> >> I am wondering, why people would use Mainframe computers.?
> >> What are the major reasons for using mainframes.?
> >> And what are the type of applications that mainframe would be used for?
> >
> > Well up untill recently Mainframes could crunch large formuls and
> > numbers faster and more percice (gerr.. Missing my spell checker).
> 
> Nah.  A DEC Alpha is still the fastest single CPU on the market, and
> mainframe CPU speed hasn't had much of an edge on microprocessor CPU
> speed since the mid 1980's.
> 
> Where mainframes really win is in massive I/O bandwidth.  If you want
> multimedia servers, with huge disk farms and massive network bandwidth,
> a mainframe may serve you better than the competition.  Even here,
> though the super-micros built by folks like SGI and HP are chewing
> away at the edge once held by mainframes.
> 
> If you're stuck cramming your I/O through a SCSI bus, you'll never match
> the performance of a system with multiple independent main memory busses
> and multiple DMA channels that can move data at memory speed without
> noticably slowing down the CPU.  Of course, even in this arena,
> minicomputers of the 1970's began to nibble at the mainframe market
> (the Modcomp IV computer, a 32-bit mini delivered in 1974, had 4 memory
> busses, 2 for I/O and 2 used by the CPU, one for instruction fetch and
> one for operands).
> 
> If you've got a legacy of ancient COBOL code, some of which was last
> compiled 30 years ago and the source code itself is lost, you're likely
> to want a mainframe!  IBM and UNISYS still make good money selling
> mainframes to folks in that bind, where performance isn't the issue
> but compatability is everything.
> 
>                                         Doug Jones
>                                         jo...@cs.uiowa.edu

I agree, but I think another major advantage of mainframes is
concurrency. We have 35,000 users with sub second response time (plus
the 3 second satellite transmission time that we can not control). PC
servers can't handle that concurrency. 

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