Processor ARM Cortex A7: specifications and reviews

ARM Cortex A7 . In this material we will talk about the processor architecture ARM Cortex A7 . Semiconductor products based on it can be found in smartphones, routers, tablet PCs and other mobile devices, where it until recently occupied the leading positions in this segment of the market. Now it is gradually being replaced by newer and more recent processor solutions.

Brief information about the company ARM

началась в 1990 году, когда она была основана Робином Саксби. The history of ARM began in 1990, when it was founded by Robin Sachsby. The basis for its creation was a new microprocessor architecture. , то после образования данной компании появилась достойная альтернатива в виде RISC. If before that the dominant position in the CPA market was occupied by x86 or CISC , then after the formation of this company, a worthy alternative appeared in the form of RISC. In the first case, the execution of the program code was reduced to 4 stages:

1. Obtaining machine instructions.

2. Performing a microcode conversion.

3. Obtaining micro instructions.

4. Step-by-step implementation of micro instructions.

сновная же идея архитектуры RIS С состояла в том, что обработку программного кода можно свести к 2 этапам: The main idea of the architecture of RIS C was that the processing of the program code can be reduced to 2 stages:

1. RISC- инструкций. Getting RISC instructions.

2. RISC- инструкций. Processing of RISC instructions.

ак в первом, так и во втором случае есть как плюсы, так и существенные недостатки. As in the first, and in the second case there are both pluses and significant drawbacks. RISC ( в том числе и ARM Cortex A7 , представленная 2011 году) — рынок мобильных устройств. X86 has successfully won the computer market, and RISC ( including ARM Cortex A7 , introduced in 2011) - the market for mobile devices.

The history of the appearance of the architecture Cortex A7. Key Features

As a basis for "Cortex A7" acted "Cortex A8". The main idea of the developers in this case was to increase performance and significantly improve the energy efficiency of the processor solution. . This is exactly what ARM engineers did. Another important feature in this case was that it was possible to create a CPU with the technology big.LITTLE. That is, the semiconductor crystal could include 2 computational modules. One of them was aimed at solving the most simple problems with minimal power consumption and, as a rule, in this role, the kernels "Cortex A7" played. The second was designed to run the most complex software and was based on the computational blocks "Cortex A15" or "Cortex A17". Officially, "Cortex A7" was presented, as was noted earlier, in 2011. Well, the first ARM Cortex A7 processor was released a year later, that is in 2012.

Production technology

Initially, semiconductor products based on A7 were manufactured according to technological standards of 65 nm. Now this technology is hopelessly outdated. In the future, two more generations of A7 processors were released at 40 nm and 32 nm tolerance standards. But they have already become irrelevant. The most recent CPU models based on this architecture are already manufactured at 28 nm, and they can still be found on sale. Further transition to newer technological processes with new standards of admission and obsolete architecture is hardly to be expected. Chips based on the A7 now occupy the most budget segment of the mobile device market and are gradually being replaced by gadgets based on the A53, which, with the same energy efficiency parameters, has a higher level of performance.

Architecture of the microprocessor core

1, 2, 4 or 8 cores can be part of the CPU based on ARM Cortex A7. The characteristics of the processors in the latter case indicate that the chip consists of essentially 2 clusters of 4 cores each. 2-3 years, entry-level processors were based on chips with 1 or 2 compute modules. The average level was occupied by 4-nuclear solutions. Well, the premium segment was for 8-core chips. Each microprocessor core based on this architecture included the following modules:

• лок обработки чисел с плавающей запятой ( FPU). Floating-point number processing unit ( FPU).

• Level 1 cache.

• NEON для оптимизации работы ЦПУ. The NEON block for optimizing the CPU.

• ARMv7. Computing module ARMv7.

There were also the following common components for all cores in the CPU:

• Cache L2.

• CoreSight Core Control Module .

• Controller of data bus AMVA with a bit capacity of 128 bits.

Possible frequencies

The maximum clock frequency for a given microprocessor architecture can vary from 600 MHz to 3 GHz. It should also be noted that this parameter, which indicates the maximum impact on the performance of the computer system, is changing. And the frequency is immediately affected by three factors:

• Level of complexity of the task.

• The degree of software optimization for multithreading.

• The current value of the temperature of a semiconductor crystal.

As an example, consider the algorithm of the MT6582 chip, which is based on A7 and includes 4 computational units, whose frequency varies from 600 MHz to 1.3 GHz. In idle mode, this processing unit can have only one block of calculations, and it operates at the minimum possible frequency of 600 MHz. A similar situation will occur when a simple application on a mobile gadget is launched. But when a resource-intensive toy with optimization for multithreading appears in the task list, all 4 blocks of processing the program code at 1.3 GHz will automatically start working. As the CPU warms up, the hotter cores will lower the frequency or even turn off. On the one hand, this approach ensures energy efficiency, and on the other hand - an acceptable level of chip speed.

Cache memory

Only 2 cache levels are provided in ARM Cortex A7. The characteristics of the semiconductor crystal, in turn, indicate that the first level is necessarily divided into 2 equal halves. должна хранить данные, а другая — инструкции. One of them must store data, and the other - instructions. азмер кеша на 1-ом уровне по спецификациям может быть равен 64 Кб. The total size of the cache at the 1st level by specifications can be equal to 64 KB. As a result, we get 32 KB for the data and 32 KB for the code. е ть от конкретной модели ЦПУ. The second level cache in this case will depend on the particular CPU model. The smallest volume of it can be 0 MB (that is, absent), and the largest - 4 MB.

The controller of operative memory. Its features

The built-in memory controller is equipped with any ARM Cortex A7 processor. Characteristics Technical plan indicate that it is oriented to work in conjunction with RAM standard LPDDR3. The recommended operating memory frequency in this case is 1066 MHz or 1333 MHz. The maximum size of RAM, which can be found in practice, for a given model of the chip is 2 GB.

Integrated graphics

As expected, these microprocessor devices have an integrated graphics subsystem. рекомендует использовать в сочетании с этим ЦПУ графическую карту собственной разработки Mali - 400MP2 . The company-manufacturer ARM recommends to use in combination with this CPU a graphic card of the own design Mali - 400MP2 . But its performance is often not enough to unlock the potential of a microprocessor device. Therefore, chip designers use more efficient adapters in combination with this chip, for example, Power VR6200.

Software Features

Three types of operating systems are aimed at ARM processors:

• от поискового гиганта Google. Android from the Google search giant .

• от APPLE. IOS from APPLE.

• от «Майкрософт». Windows Mobile from Microsoft.

All the rest of the system software has not yet received much distribution. The largest share in the market for such software, as it is not difficult to guess, is precisely Android. This system has a simple and intuitive interface and the entry-level devices are very, very affordable. Prior to version 4.4 inclusive, it was 32-bit, and with 5.0 began to support 64-bit computing. , в том числе и ARM Cortex A7. This OS successfully operates on any family of the RISC architecture CPU, including ARM Cortex A7. The engineering menu is another important feature of this system software. With its help, you can significantly reconfigure the capabilities of the OS. Access to this menu can be obtained using the code, which for each model of the CPU is individual.

Another important feature of this OS is the installation of all possible updates automatically. Therefore, even new features may appear on the chips of the ARM Cortex A7 family. Firmware can add. The second system is aimed at APPLE mobile gadgets . Such devices mainly occupy the premium segment and have corresponding levels of speed and cost. пока не получила большого распространения. The latest OS in the face of Windows Mobile has not yet received much distribution. Devices based on it exist in any segment of mobile gadgets, but here a small amount of applied software in this case is a deterrent to its distribution.

Processor Models

The most affordable and least productive in this case are 1-core chips. The most widespread among them was MT6571 from the company MediaTek. On the step above are dual-core CPU ARM Cortex A7 Dual Core. As an example, you can bring MT6572 from all the same manufacturer. An even higher level of performance was provided by Quad Core ARM Cortex A7. The most popular chip from this family is MT6582, which can now even be found in mobile gadgets of the entry level. Well, the highest level of performance provided by 8-core CPUs, which belonged to the MT 6595.

Further development prospects

For the present, mobile devices based on a 4X ARM Cortex A7 semiconductor processor are on store shelves. This and MT6580, MT6582 and Snapdragon 200. All these chips include 4 computational units and have an excellent level of energy efficiency. Also the cost in this case is very very modest. But still the best times of this microprocessor architecture are already behind. Peak sales of products based on it fell for 2013-2014, when the market for mobile gadgets, it had virtually no alternative. And in this case we are talking about budget devices with 1 or 2 computational modules, as well as flagship gadgets with an 8-core CPU. At the moment, it gradually replaces the market "Cortex A53", which is essentially a modified 64-bit version of A7. At the same time, the main advantages of its predecessor, it retained entirely and completely, and the future is certainly behind it.

Opinion of experts and users. Real feedback on chips based on this architecture. Advantages and disadvantages

Certainly, a landmark event for the world of mobile devices was the emergence of the architecture of microprocessor devices ARM Cortex A7. The best proof of this was that the devices on its base have already been successfully sold for more than 5 years. Of course, now the capabilities of the A7-based CPU are not enough even for solving middle-level problems, but here the most simple program code on such chips is still functioning successfully to this day. The list of such software includes video playback, listening to audio recordings, reading books, web surfing and even the most simple toys in this case will be launched without any problems. It is on this and focus on the leading thematic portals, dedicated to mobile gadgets and devices as leading experts of this plan, and ordinary users. The key disadvantage of A7 is the lack of support for 64-bit computing. Well, the main advantages of it can be attributed to the perfect combination of energy efficiency and productivity.

Results

это целая эпоха в мире мобильных устройств. Of course, the ARM Cortex A7 architecture is a whole era in the world of mobile devices. It was with its advent of mobile devices have become available and quite productive. And one fact that it has been successfully sold for more than 5 years, is proof of this. But if in the beginning gadgets on its base were occupied by the average and premium segments of the market, now they have only a budget class. This architecture is obsolete and gradually becomes a thing of the past.