▷ Units of measurement in computing: bit, byte, mb, terabyte and petabyte

In this article we will see the units of measurement in computing, we will learn what they consist of, what they measure and the equivalence between each of them, bit, byte, Megabyte Terabyte and Petabyte . There are many more! Do you know them

If you have ever read any of our reviews and articles, surely you will have come across certain values ​​expressed in these units of measurement. And if you have also noticed, we usually express the measurements in networks using bits and those of storage in bytes. What then is the equivalence between them? We will see all this in this article.

Index of contents

Knowing this type of measures is really useful when buying different computer components, since we can avoid being deceived. Perhaps we will one day hire the internet service of some operator and tell us the figures in Megabits and we will be so happy to check our speed and see that it is much lower than we originally thought. They have not deceived us, they will only be measures expressed in another magnitude.

It also usually happens with the frequency of processors and RAM memories, we need to know the equivalence between Hertzios (Hz) and Megahertzios (Mhz) for example.

To clarify all these doubts, we have proposed to develop a tutorial as complete as possible about all these units and their equivalents

What is a Bit

Bit comes from the words Binary Digit or binary digit. It is the unit of measurement for measuring the storage capacity of a digital memory, and is represented by the magnitude "b". The bit is the numerical representation of the binary numbering system, which tries to represent all the existing values ​​by means of the values ​​1 and 0. And they are directly related to the values ​​of electrical voltage in a system.

In this way we can have a positive voltage signal, for example 1 Volt (V) that will be represented as a 1 (1 bit) and a null voltage signal, that will be represented as a 0 (0 bit)

Actually, the operation is the opposite and an electrical pulse is represented with a 0 (negative edge), but for the explanation, the most intuitive for humans is always used. From the machine's point of view it is exactly the same, the conversion is direct.

So, a succession of bits represents a chain of information or electrical pulses that will make a processor perform a certain task. Our CPU only understands these two states, voltage or non-voltage. With the union of many of these, we manage to do certain tasks on our machine.

Bit combination

With one bit we can only represent two states in a machine, but if we start to join some bits with others we can get our machine to encode more variety and information.

For example, if we had two bits, we could have 4 different states, and therefore we could do 4 different operations. Let's see for example how we could control two buttons:

0	0	Don't press any button
0	one	Press button 1
one	0	Press button 2
one	one	Press both buttons

In this way it is possible to make machines like the ones we currently have. Through the combination of bits it is possible to get to do everything that we see today in our team.

The binary system is a system of base 2 (two values) so to determine how many combinations of bits we can make, we would only have to raise the base to the nth power according to the bits we want. For example:

If I have 3 bits, I have 2 ³ possible combinations or 8. Is it true ?:

0	0	0
0	0	one
0	one	0
0	one	one
one	0	0
one	0	one
one	one	0
one	one	one

If it had 8 bits (octet) we would have 2 ⁸ possible combinations or 256.

Most significant bits

As in any numbering system, 1 is not the same as 1000, the zeros on the right count a lot. We call the most significant or highest value bit (MSB) and the least significant or least value bit.

Position	5	4	3	two	one	0
Bit	one	0	one	0	0	one
Value	2 5	2 4	2 3	2 2	2 1	2 0
Decimal value	32	16	8	4	two	one
	MSB					LSB

As we can see, the greater the position to the right, the greater the value of the bit.

Processor Architectures

Surely we all relate in the first instance the value of bits with the architecture of a computer. When we talk about 32-bit or 64-bit processors we are referring to the ability to perform operations that these have, specifically the ALU (arithmetic-logic unit) to process instructions.

If a processor is 32 bits, it will be able to work simultaneously with groups of bits of up to 32 elements. With a 32 bit group we can represent 2 ³² different types of instructions or 4294967296

One of 64 therefore would be able to work with words (instructions) of up to 64 bits. The more bits in a group, the greater the capacity to perform operations will have a processor. Similarly with a group of 64 we can represent 2 ⁶⁴ types of operations., Ridiculously large amount.

Storage units: the byte

For their part, storage units measure their capacity in bytes. A byte is a unit of information equivalent to an ordered set of 8 bits or an octet. The magnitude with which a byte is represented is with the capital “ B ”.

So in one byte we will be able to represent 8 bits, so the conversion is quite clear now

1 Byte = 8 bits

Go from Bytes to bits

To convert from Byte to bit we will only have to carry out the appropriate operations. If we want to go from Bytes to bits, we will only have to multiply the value by 8. And if we want to go from bits to Bytes we will have to divide the value.

100 Bytes = 100 * 8 = 800 bits

256 bits = 256/8 = 32 bytes

Byte Multiples

But as we see the Byte is a really small measure compared to the values ​​that we currently handle. This is why measures representing the multiples of the Bytes have been added to adapt to the times.

Strictly, we should use the equivalence between the multiples of the Byte through the binary system, since it is the base on which the numbering system works. As we do with quantities such as weight or meters, we can also find multiples in this representation system.

Byte Multiples in International Measurement System

Computer scientists always like to represent things with their real values, as was the previous example. But if we are engineers, we would also like to have the international numbering system as a reference. And it is precisely for this reason that these values ​​differ according to the system we use, and it is because the base 10 of the decimal numbering system is used to represent the multiples of each unit. Then, according to the International Electrotechnical Commission (IEC), the table of multiples of Byte and name would be as follows:

Magnitude name	Symbol	Factor in decimal system	Value in binary system (in Bytes)
Byte	B	10 0	one
Kilobyte	KB	10 3	1, 000
Megabyte	MB	10 6	1, 000, 000
Gigabyte	GB	10 9	1, 000, 000, 000
Terabyte	TB	10 12	1, 000, 000, 000, 000
Petabyte	PB	10 15	1, 000, 000, 000, 000, 000
Exabyte	EB	10 18	1, 000, 000, 000, 000, 000, 000
Zettabyte	ZB	10 21	1, 000, 000, 000, 000, 000, 000, 000
Yottabyte	Yb	10 24	1, 000, 000, 000, 000, 000, 000, 000, 000

Why 1024 instead of 1000

If we stick to the binary numbering system, we should use this pass to create multiples of the Byte. Thus:

1 KB (Kilobyte) = 2 ¹⁰ Bytes = 1024 B (Bytes)

In this way we will have the following table of multiples of the Byte:

Magnitude name	Symbol	Factor in binary system	Value in binary system (in Bytes)
Byte	B	2 0	one
Kibibyte	KB	2 10	1, 024
Mebibyte	MB	2 20	1, 048, 576
Gibibyte	GB	2 30	1, 073, 741, 824
Tebibyte	TB	2 40	1, 099 511, 627, 776
Pebibyte	PB	2 50	1, 125 899, 906, 842, 624
Exbibyte	EB	2 60	1, 152 921, 504, 606, 846, 976
Zebibyte	ZB	2 70	1, 180 591, 620, 717, 411, 303, 424
Yobibyte	Yb	2 80	1, 208 925, 819, 614, 629, 174, 706, 176

What each and every one of us does, because they skillfully unite these two measurement systems. We take the accuracy of the binary system together with the nice names of the international system to always talk about that 1 Gigabyte is 1024 Megabytes. Let's be honest, who would think to ask for a 1 Tebibyte hard drive, they would possibly call us stupid. Nothing is further from reality.

Why does my hard drive have less capacity than I have purchased?

After reading this, surely you will have noticed one thing, the storage capacities in the international system are smaller than those represented in binary. And surely we have also noticed that hard drives, absolutely whenever we buy one come with less capacity than originally promised. But is this true?

What happens is that hard drives are marketed in terms of decimal capacity according to the international system, so one Gigabyte is equivalent to 1, 000, 000, 000 Bytes. And operating systems like Windows, use the binary numbering system to represent these figures, which as we have seen, differ the greater the capacity we have.

If we take this into account and go to see the properties of our hard drive, we could find the following information:

We have bought a 2TB hard drive, so why do we only have 1.81TB available ?

To give the answer we will have to do the conversion between one system and another. If the quantity is represented in bytes, we must take the equivalent of the corresponding numbering system. So:

Capacity in decimal system / Capacity in binary system

2, 000, 381, 014, 016 / 1, 099, 511, 627, 776 = 1.81 TB

In other words, our hard drive really has 2TB, but in terms of the international system, not the binary system. Windows gives it to us in terms of the binary system and it is precisely for this reason that we see less on our computer.

To have a 2TB hard drive and see it that way. Our hard drive should be:

(2 * 1, 099, 511, 627, 776) / 2, 000, 000, 000, 000 = 2.19TB

Communications media units

Now we turn to see the measures we use for digital communication systems. In this case we find much less discussion, since we all directly represent these units through the international system, that is, in base 10 according to the decimal system.

So to represent the data transmission rate we are going to use the bit per second or (b / s) or (bps) and their multiples. Because it is a measure of time, this elemental magnitude is introduced.

Magnitude name	Symbol	Factor in decimal system	Value in binary system (in bits)
bit per second	bps	10 0	one
Kilobit per second	Kbps	10 3	1, 000
Megabit per second	Mbps	10 6	1, 000, 000
Gigabit per second	Gbps	10 9	1, 000, 000, 000
Terabit per second	Tbps	10 12	1, 000, 000, 000, 000

Frequency

Frequency is a quantity that measures the number of oscillations that an electromagnetic or sound wave undergoes in one second. An oscillation or cycle represents the repetition of an event, in this case it will be the number of times a wave repeats. This value is measured in hertz whose magnitude is the frequency.

A hertz (Hz) is the oscillation frequency that a particle undergoes in the period of one second. The equivalence between frequency and period is as follows:

So, in terms of our processor, it measures the number of operations that a processor is capable of performing per unit of time. Let's say that each wave cycle would be a CPU operation.

Hertz Multiples (Hz)

As with the previous measurements, it has been necessary to invent measures that exceed the basic unit that is the hertz. This is why we can find the following multiples of this measure:

Magnitude name	Symbol	Factor in decimal system
picohertz	pHz	10-12
nanohertz	nHz	10 -9
microhertz	µHz	10 -6
millihertz	mHz	10 -3
centihertz	cHz	10 -2
decihertzio	dHz	10 -1
Hertz	Hz	10 0
Decahertzio	daHz	10 1
Hectohertz	hHz	10 2
Kilohertzio	kHz	10 3
Megahertz	MHz	10 6
Gigahertz	GHz	10 9
Terahertzio	THz	10 12
Petahertzio	PHz	10 15

Well, these are the main measures used in computing to measure and evaluate the functioning of the components.

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We hope this information has helped you better understand the operating measurement units of a computer.