Obviously this is not an introductory presentation of a Computer Science Course. And I will try here to do what Charles and Ray Eames did when they were praised by Tom Watson Jr and the team, when they said: “Charlie can put what a computer does into a little cartoon-like film and in the course of twelve minutes have everybody in the room understanding—how they work.”
The best place to start is to take a look in the excellent job about How did the Apollo flight computers get men to the moon and back .
The key catch here is the Task which is under the computer control, or responsibility, if you will.
The basic task of any computer is to transform Data into information and decide, or help somebody what to do with it.
Data, generally speaking, are things known or assumed as facts, making the basis of reasoning or calculation.
In computing, data is the quantity, character or the symbol on which operations are to be performed by the computer, being stored and transmitted in some form, in most cases through electrical signals, which can be recorded through some kind of media, such as solid state, magnetic, optical, mechanical, or whatever technology which allows its recovery after.
Information is data with meaning to whatever you can conceive and which is attained eventually with the use of a computer
In a very broad sense it boils down mostly to mathematical calculations or process control, being that that from the bulk of an infinite list of processes, those associated with daily operations of any size world’s corporations are the main stream. General ledger, pay roll, stock control and everything related to sales were, up until the early nineties more than half than anything computers did. Today (2018) it is difficult, if not impossible, specially for the lack of criteria, to establish that. We are on the verge of creation of virtual reality and modeling for just about anything with a long list of possibilities from which perhaps we should mention Computer Aided Design (CAD), image and voice processing, games and, why not, virtual reality.
It should be mentioned that until the mid-Until de mid 1990s, mainframes provided the only acceptable means of handling the data processing requirements of a large business. These requirements were then (and are often now) based on running large and complex programs, which Personal Computers, or smaller non main frames computers are getting into.
The first and most important consideration you have to have in mind is what became very clear in the presentation about the Apollo landing analysis: Mission Critical Application vs. Applications in General.
The old 360 architecture, no matter disguised under whatever name, or what advance it received, is still what you have to have if you want it done securely.
People do not know but it is impossible to bug an IBM Main Frame Operational System, just for starts.
Bear in mind that your ATM machine is a PC, but at the other end it is a Main Frame. As matter of fact, almost all ATM machines in the USA as of today, 2018, run on XP, which had its support discontinued by Microsoft. Bear also in mind that, when a business application is accessed through a Web browser, there is often a mainframe computer performing crucial functions behind the scenes.
As it was the case in the Apollo landing set up.
Scalability and Reliability is also a very important aspect. For example, a banking institution could use a mainframe to host the database of its customer accounts, for which transactions can be submitted from any of thousands of ATM locations worldwide
Businesses today rely on the mainframe to:
- Perform large-scale transaction processing (thousands of transactions per second)
- Support thousands of users and application programs concurrently accessing numerous resources
- Manage terabytes of information in databases
- Handle large-bandwidth communication
Take a look, if you didn’t, at mathematical calculations and the computer.