Thursday, July 9, 2009

What is Mainframes??

The term ‘MainFrame’ brings to mind a giant room of electronic parts that is a computer, referring to the original CPU cabinet in a computer of the mid-1960’s. Today, Mainframe refers to a class of ultra-reliable large and medium-scale servers designed for carrier-class and enterprise-class systems operations. Mainframes are costly, due to the support of symmetric multiprocessing (SMP) and dozens of central processors existing within in a single system. Mainframes are highly scalable. Through the addition of clusters, high-speed caches and volumes of memory, they connect to terabyte holding data subsystems.
The first mainframe vendors were GE, Control Data, IBM, NCR, RCA, Burroughs, Honeywell and Univac. Collectively known as “IBM and the Seven Dwarfs”. Through mergers, these vendors shifted within the industry, becoming “IBM and the BUNCH”. Running a version of Unix or Linux, these vendors led by IBM now include Amdahl (Fujitsu), Unisys and Sun among others.
Online training includes the History of Mainframes, Job Control Language (JCL) and thorough tutorials on the components, transactions and functions of the Customer Information Control System (CICS). Mainframe professionals can find well-paid work in highly respected and breakthrough technology companies throughout the world as Mainframe Systems Programmers and Project Managers.

History and Evolution of Mainframes:
Some of the early mainframes which were developed starting from the year of 1942 are ENIAC, MARK1, BINAC, UNIVAC. ENIAC is also called as electronic numerical integrator and calculator was developed in the year 1942. This mainframe machine weighed in tones and consumed enormous electric power. It had thousands of vacuum tubes, relays resistors, capacitors, and inductors inside it.In the year 1951, UNIVAC-I was developed specially for the US Census Bureau. The major difference between UNIVAC and ENIAC was the processing of digits. IBM was producing and releasing mainframes in the market at all periods from past till present with the successive development of IBM Series starting with System/360.
Mainframe Channel:
A mainframe channel connect to one or more controllers via either pairs of large "bus and tag" cables or, fiber optic ESCON (Enterprise System CONnection) cables and FICON, which has the ability controlling one or more devices. This is one of the important term in mainframe technology since it has the ability of take care of huge input and output functions.
DASD stands for Direct Access Storage Device. This indicates to any type of storage that was directly (randomly) addressable.
LPAR stands for Logical Partition and is a powerful hardware or firmware feature implemented in all mainframe systems. By this feature it is possible to create partitions and by which CPUs and I/O sub-systems can be shared between logical partitions.

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