MAINFRAMES or CENTRAL UNIT  What are they? ▷ 2020

Do you know the concept of central unit? Do you know what mainframes are? Although unknown to most, these teams or systems have a very important job in today’s society.

Are megacomputers with immense capacity to work millions of data per second, with the corresponding effects that this has when making comparisons, mathematical operations, etc.

If you have found it curious, you cannot miss this post in which we are going to explain you in detail what are these computational elements as well as all its history and evolution in addition to their similarities and differences with supercomputers.

What is a Mainframe or Central Unit in computing? Definition

Mainframe or Central Unit

The mainframe, the central unit in our language, is a large computer (first meters and then, over the years, several decimeters) designed to work with data in unthinkable volumes, primarily for calculation and, later, with other purposes, both for information processing and storage

This assumes, of course, that its characteristics are highly regarded, counting on very powerful memories and processors, very far from what any average user can know today. It stands out from the fact that, thanks to its pampered engineering, being able to keep the equipment operational for years, even repairing it without having to turn it off, which makes it more efficient than it can.

In cases where false terminals are embraced, we also have the ability to work with various operating systems, functioning as if it were several virtual machines, although, obviously, we are talking about a single machine that, yes, can redistribute its resources among its virtual terminals. Thus, we talk about an exemplary logical partition management system.

For its characteristics, its usual use today is in banking, as a central system, although it is also used to streamline the work of various public bodies as well as in many corporations that, due to their volume of information, have accounts of this equipment instead of having dozens of personal computers and their corresponding workers on the payroll. Some examples would be airlines, stock markets or in the Treasury.


The mainframe appears to improve the performance of calculating computers with micro-perforated cards that had been in use for several decades, since the beginning of the century.

It is the year 1939 that sees how, from Harvard, something bigger begins to cook, literally and metaphorically speaking. Five years later, In 1944, The Harvard Mark I or ASCC was published, the first machine that IBM called a “mainframe” or central unit.

The Harvard Mark I first mainframe

History and evolution

We started, as with all computers, with a huge computer that occupied a huge room in the university and which worked in parallel with calculation algorithms to perform the four basic operations of mathematics: addition, subtraction, division and multiplication, acting as a synchronous calculator.

This could operate with up to two tens of decimal places by having 60 physical records of constants and 72 counters for temporary results. Curious fact is that the manufacture of these elements required 800 km of wiring.

He worked with punched cards but it should be noted that information could also be entered from other sources such as mechanical switches or paper. The output of this was also given on cards or paper, making use of mechanical writing machines.

The following decade, as might be expected, was marked by constant research to achieve every possible improvement of this central unit. IBM launches SSEC, incorporating both mechanical and electronic parts. The function was identical to the previous set, the calculation. It should be mentioned, as an interesting fact, that the first thing this computer worked on was to calculate the distance of the Moon in relation to the planets in our system, for which it took 6 months.

War brings us the birth of the one who was first mainframe with digital information processing system, with the programs included in its internal memory, the IBM 701. This was specifically designed to work for the US in the Korean War, who wanted it to be useful when designing ammunition and aerospace craft. It is shocking to know that, as he was the one who started the modern era of computing, he only sold 19 units.

From now on, the efforts of the engineers fell to improve the design and that it could be adapted to the novelties that science was learning. A large part of these efforts was devoted to the physicality of the equipment and some of its components, always looking for the set to be more efficient and to reduce the physical error.

The digital age begins with the IBM 7000, launched to unseat vacuum valve technology once and for all, and for which was provided with transistors. This happened in 1964.

The first configurable mainframe is the S / 360, a line born to fit all pockets and requirements. This made them really attractive to a much larger audience, something for which their multipurpose team orientation.

s 360 mainframe

The following line was launched, the S / 370, based on 32-bit architecture, backward compatible with the previous contemporary of personal computers and harvester of great successes, remaining two decades in the market.

Despite the clones that emerged, IBM had a product without competition, so was able to pool his efforts on improvements for this and not in quickly launching another new model. New processors were designed, the equipment was adapted to new interfaces, Linux was introduced tailor-made for these mainframes, IBM designed its own operating system …

The new century brings with it a new architecture, the z / Architecture, also from IBM, jumping to 64 bits but maintaining, again, backward compatibility with previous models.

Needless to say, IBM was not the only one to launch central units. Although, we cannot deny that it was the one that marked the history, milestone by milestone, of these teams.

What main characteristics does this type of super computers present?

As you can guess after reading all the above, there are a number of components or features that are essential for this type of computer while others are not even taken into consideration.


The aspects to consider when it comes to hardware would be:

  • A big size, requiring special installations and even industrial refrigeration.
  • The quality of internal engineering they include, which obviously makes them more reliable and secure.
  • They have one centralized structure, which makes task management easier and maintenance less expensive.
  • They control hundreds of input devices Y output peripherals.


In relation to the software, what is valued in a central unit is:

  • For the CPU, its speed. It works with a volume of operations of billions per second.
  • For internal memory, simply your capacity.
  • In the case of external, it is necessary to consider, in addition to the capacity, the file transfer speed.
  • How adequate the results are in relation to input and output peripherals, especially when it comes to speed.

Is a Central Unit the same as a Super Computer?

Absolutely not. Although it is not easy to explain what the differences are, because, after all, both concepts refer to large computers with greater power.

However, there is a clear difference, at least in theory. This is the fact of having mainframe as a problem-solver element limited by peripherals and reliability itself of the elements and supercomputer as a solver of the problems that occur when being limited by the calculation speed.

Thus, we find the following:


  • Works even with thousands of processors, speaking, of course, of absolutely massive jobs.
  • Its programming is really complicated.
  • It is optimized to work in extremely complicated calculations that will take place in memory of of the team.
  • Its main use is given in the military and scientific fields.

Central unit

  • The number of processors is small, finding mainframes that even have only one (very powerful, yes).
  • There is no programming parallelism and this is much simpler.
  • It is optimized for “simple” calculations that require the use of external data with access in database.
  • Its applications are administrative and business.

If you have any questions, leave them in the comments, we will answer you as soon as possible, and it will also be of great help to more members of the community. Thank you! 😉

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