The Definition and meaning of mainframe has shifted from its original reference to the main housing, or frame, that contained the central processing unit (CPU) of the computer. In those days, all computers were big-like the size of a garage and the frame for the CPU might have been as big as a walk-in closet. Now mainframe refers to the kind of large computer that runs an entire corporation.
While "large" can still mean as big as a room, most of today's "mainframes" are much smaller, although they're still quite a bit bigger than a personal computer or even a minicomputer. A mainframe has an enormous storage space on disk and tape (like thousands of kilobytes, measured in gigabytes), and an enormous amount of main memory. Theoretically, it works a lot faster than the fastest personal computer. A mainframe also costs big bucks, from half a million or so on up.
In today’s world where all the business, transactions, communications are real time. So to perform all this task, a powerful computer require on the server side, which processes the instructions and provides the output in seconds. According to the usage of computers in today’s world, we can categories computer in Supercomputer, Mainframe Computer, and Mini Computer and microcomputer categories. A mainframe computer is the fastest computer after supercomputer to execute complex and lengthy calculations. A mainframe computer is more powerful than Mini and Microcomputer, but less powerful than Supercomputer. A mainframe computer is used in the large organization.
A mainframe computer is a combination of memory (RAM) and many processors. It acts as a central processing unit for many workstations and terminals connected with it. A mainframe computer is used to process the large and huge amount of data in petabytes. It can control thousands of user ’s. Name ‘Mainframe’ means that a frame for holding a number of processors and main memory. Mainframe computer plays a significant role in e-business where hundreds to thousands of people connect to a server to precede their request in a real time. Similarly, In banking, government, education system mainframe computer play a valuable role.
Mainframes are tended by special technicians who feed them the programs they run and who scramble around trying to fix them whenever they stop working, which is often. All mainframes are multi-tasking, multi-user machines, meaning they are designed so many different people can work on many different problems, all at the same time.
Mainframe computer initially created in early 1950’s.Initially, the size was too big because of the vacuum tube. But after the invention of transistors main frame computer size get reduced.
Mainframes serve most often as information stores and processors. An army of smaller computers is connected to the mainframe. These smaller computers are not in the same room; they may be connected through phone lines across the world. Ordinary people in the company never touch the mainframe itself. Instead, they interact with the computer using a terminal, which is more or less a keyboard and a monitor connected to the mainframe with wires, or by modem over the phone lines. People use the smaller computers and get information from and send information to the mainframe.
IBM manufactured many mainframe computers for commercial, scientific and engineering use with different serial numbers. IBM manufactured 700 and 7000 series models with use of vacuum tube and transistors. In 1964, System/360 was manufactured for both commercial and scientific users. S/360 was the first computer to offer microcode. Microcode functionality makes the system modifiable without changing the computer. Now the customer can create their own application according to requirement. In 2000, Z-Series was introduced by IBM. Z-series computers are very powerful to process the instruction.
The difference between a minicomputer and a mainframe is arbitrary, and different people may use either term for the same machine. Even if you don't work for a large company, you might have contact with a mainframe: when you connect to an online information service or a commercial e-mail service from your personal computer, you are often connecting to a mainframe.
In the '60s the mainframe vendors were called "IBM and the seven dwarfs": Burroughs, Univac, NCR, Control Data, Honeywell, GE, and RCA. They turned into IBM and the BUNCH after Honeywell ate GE's computer division and Univac ate RCA's.
Components of Mainframe computer
Mainframe computer provide reliable and secure process execution. Mainframe computer has some components to perform task.
CPU: CPU contains the processors, memory, control circuits, and interfaces for channels. A channel is an independent path between I/O devices and memory. This path is used for data movements and for controlling the computer components.
Controllers: Channels are used to connect devices with control units. Channel is also known as a bus. In Mainframe computer, the different control unit (internal circuit and logic) is used for different -different devices like tape, disk. Control unit is further connected with storage unit.
Cluster controller: Cluster controller is a device to connect channel terminal to host system. Cluster controls have two types
Channel-attached cluster controllers and link-attached cluster controllers.
Cluster controllers provide advanced features like IBM Token Ring attachment interfaces, management, and monitoring.
I/O channels: During I/O connectivity, we used some term like IOCDS, ESCON, FICON, CHIPD’s having unique definitions and purpose.
ICODS: ICODS stands for I/O control data set. It is a control file in I/O layer to translate physical I/O address into device address.
ESCON (Enterprise Systems Connection): is a first IBM and vendor product for connecting more than one mainframe computer and with locally attached workstations. It is Fiber Optic channel to transfer the data with the maximum speed of 17 MByte/ s. We can extend the local to mainframe network up to 60 km. It has some limitations regarding speed and network area. To make it better IBM next version was FICON. FICON (fiber connector) is used to increase the transfer speed of ESCON channel. One Ficon connector is equal to eight ESCON connector.
Multiprocessors: Multiprocessors indicate that number of processors. Multiple processors in mainframe computer used some Prefix Storage Area to process the data (For error handling and interrupt handling).Using special instruction set processor can communicate with another processor using special instruction set.
The advantage of mainframe computer
Mainframe computer has many advantages as well as disadvantages. From the last 50 years, there was a great revolution in mainframe computer in all field like size, processing speed, data transfer speed, security, and flexibility.
• Mainframe computer provides a great security against the attack of viruses, warm, spyware, malware. Encryption technique like file encryption, dataset and file encryption, network encryption, clustering encryption empower security.
• Mainframe computers are compatible with all types of software and hardware. Because different user connects with servers along with different hardware and software on their system. They can easily communicate with server-side without any interrupt.
• Mainframe computer deals with thousands of users to execute their instructions simultaneously. And can store
• Without disturbing process on the computer, we can add storage, processors or memory and extend its capability.
With some advantages, it has some disadvantage
• A mainframe computer is expensive. It is not easy to purchase a mainframe as a comparison to the microcomputer.The microcomputer is handled by the single user, but mainframe handled many users. Installation is not easy.