What is a Mainframe…?

What is a Mainframe…?

And the answer is – A type of computer, in fact a fast computer, which can handle several tasks at the same time- the ultra high-performance centralized computer made for high-volume, processor-intensive, number crunching computing, where multiple users can log-in simultaneously on time-sharing bases.

Yes, nowadays all the computers do this, but this definition of Mainframe has come up from past when there was a dearth of computing power, so, in the present times, you can differentiate a Mainframe from others by:

• Operating system: IBM’s z/OS MVS/ESA (OS/390), VM/ESA & VSE/ESA – and yes, UNIX & Linux too work on a Mainframe.
• Hardware – from IBM (mostly).
• Architecture – CISC based, with roots in 60’s and 70’s.
• Centralized processing
• An unmatched availability record – even up to four / five nines  - i.e. 99.99 /99.999 [1] – a performance record of reliability greater than 99.99+% with continuous unstopped/un-rebooted service for years.
• 1) Maximum reliable single-thread performance:  2) Maximum I/O Connectivity: 3) Maximum I/O Bandwidth [2]:

This is what Wikipedia says -” Mainframes or the Big Irons are computers used mainly by large organizations for critical applications; typically bulk data processing such as census, industry and consumer statistics, ERP, and financial transaction processing.” [3]

For programmers, Dr.Dobbs gives a more clueful article on by explaining the difference between those who know and those who don’t [4]:

As a Mainframe programmer myself, I could not resist the temptation to  include this quote from another blogger: “Leave the “real” work up to the Mainframe. The “pretty” stuff is what a PC is for” [5].

To sum up it all, this is what IBM says – it’s a style of computing! [6]

References:

[1]. http://www.byte.com/art/9804/sec5/art3.htm
[2]. http://www.mainframes.com/whatis.htm)
[3]. http://en.wikipedia.org/wiki/Mainframe_computer
[4]. http://dobbscodetalk.com/index.php?option=com_myblog&show=Mainframe-Programming-Fun.html&Itemid=29
[5]. http://techrepublic.com.com/5208-6230-0.html?forumID=102&threadID= 205674&start=0
[6]. http://publib.boulder.ibm.com/infocenter/zoslnctr/v1r7/index.jsp?topic=/com.ibm.zconcepts.doc/zconc_whatismainframe.html