What is Mainframe?




Mainframe is a big computing machine which handles thousands of users across
world.   Thousands of users can connect to one mainframe machine from different
parts of the world.  Applications written in COBOL, PL/1, ASSEMBLER, JCL, CICS, 
FORTRAN, C , Java .. etc.. runs on this machine.  Databases like IBM DB2, IMS DB...
are used on this machine. Mainframe systems were launched into market by companies 
like, IBM, AMDAHL & HITACHI. 
( AMDAHL & HITACHI stopped the production of new mainframes around year 2000).


Mainframe Computer history starts from 1950's.  In those days, Mainframe computers 
are not just the largest computers, mainframe computers are the only computers 
available in those days and only very big businesses could able to afford them. 
IBM started its Mainframe selling from 1952, by announcing IBM 700 series machines. 
After IBM 700 Mainframe series, It introduced IBM 1400 mainframe series between years 
1959 - 62. IBM announced its first general purpose mainframe computers IBM System/360 
in 1964. 


Below is the picture of mainframe computer - mainframe computer 704 series.


 picture author : Lawrence Livermore National Laborator 

Old mainframe systems used occupy large spaces. since these machines were housed in 
room-sized metal boxes or frames, which is probably how the term mainframe originated. 
Starting 1990, size of mainframe machines has reduced. Below is the picture of new 
mainframe systems.

 
Courtesy:ibm.com 
 The z990 was introduced in May 2003 as "the world's most sophisticated server." 
Building on the breakthrough technology of the predecessor eServer z900, the z990 is the ideal
cornerstone for "on demand business" and sets a new standard for enterprise-class computing.

Since 1960, IBM released many versions of mainframe systems with enhanced features. 
New Mainframe computers can serve thousands of users, manage petabytes of data.
As info i petabyte = 1000 terabytes.


How many people might be using mainframe computers, in recent fast?

Interestingly... every one who uses internet.
How it is possible? most of big organizations depends on mainframes
to host most important, mission-critical applications. They use mainframes
as servers. when user requested some info, thru web.. actual data processing happens 
at mainframe, behind the scene, user gets required data onto his personal computer. 


When a ATM user, requested for bank balance thru ATM, request go to mainframe , he 
will get required data from mainframe to ATM. here mainframe working behind scene.  
 
Businesses today rely on mainframe to 

  - Perform large-scale transaction processing
  - Support thousands of users and application programs 
  - Manage terabytes of information in databases
  - handle large-bandwidth communications


IBM's latest series of mainframe computer machines - z series machines - z9 109, z10
These machines can process one billion transactions per day.


According to one estimate done in 2002,  
   - 70% of worlds data stored on Mainframe systems.
   - 85% of al business transactions are processed on mainframes.



Other Mainframe Resources - Mainframe Basics 

What is COBOL ?
What is JCL ?
What is CICS ?






  

                                 









References - 

wikipedia mainframe computer

computing history museum - Mainfraem Computer

Mainframe Computer Album 

IBM Redbooks, ibm library.


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