All about the Apple A7 processor.

This article will discuss processor architecture.. Semiconductor products based on it can be found in smartphones, routers, tablet PCs and others. mobile devices, where until recently it occupied a leading position in this market segment. Now it is gradually being replaced by newer and fresher processor solutions.

Brief information about the ARM company

ARM's history dates back to 1990, when it was founded by Robin Saxby. The basis for its creation was a new microprocessor architecture. If before this the dominant positions in the CPU market were occupied by x86 or CISC, then after the formation of this company worthy alternative in the form of RISC. In the first case, the execution of the program code was reduced to 4 stages:

Receiving machine instructions.

Perform microcode conversion.

Receiving microinstructions.

Step-by-step execution of microinstructions.

ABOUT the basic idea of ​​architectureRISC was that the processing of program code can be reduced to 2 stages:

Receipt RISC- instructions.

Treatment RISC- instructions.

TO Both in the first and second cases there are both advantages and significant shortcomings. x86 successfully conquered the computer market, andRISC ( including, introduced in 2011) - the mobile device market.

The history of the Cortex A7 architecture. Key Features

The basis for “Cortex A7” was “Cortex A8”. The main idea of ​​the developers in in this case The goal was to increase performance and significantly improve the energy efficiency of the processor solution. This is exactly what ARM engineers ultimately achieved. Another important feature in this case was that it became possible to create CPUs with big.LITTLE technology. That is, the semiconductor crystal could include 2 computing modules. One of them was aimed at solving the simplest problems with minimal power consumption and, as a rule, the Cortex A7 cores played this role. The second was intended to run the most complex software and was based on the Cortex A15 or Cortex A17 computing units. Officially, “Cortex A7” was presented, as noted earlier, in 2011. Well, the first processor ARM Cortex A7 was released a year later, that is, in 2012.

Production technology

Initially, semiconductor products based on A7 were produced according to 65 nm technology standards. Now this technology is hopelessly outdated. Subsequently, two more generations of A7 processors were released according to tolerance standards of 40 nm and 32 nm. But they have now become irrelevant. The latest CPU models based on this architecture are already manufactured according to 28 nm standards, and these are the ones that can still be found on sale. A further transition to newer ones with new tolerance standards and outdated architecture is unlikely to be expected. A7-based chips are now the most popular budget segment market of mobile devices and they are gradually being replaced by gadgets based on the A53, which, with almost the same energy efficiency parameters, has more high level speed.

Microprocessor core architecture

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

B floating point processing unit (FPU).

Level 1 cache.

Block NEONto optimize CPU performance.

Computing moduleARMv7.

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

Cash L2.

CoreSight core control unit.

AMBA data control bus controller with 128-bit capacity.

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 performance computing system, changes. Moreover, the frequency is influenced by three factors at once:

The level of complexity of the problem being solved.

Optimization level software for multithreading.

Current temperature value semiconductor crystal.

As an example, consider the operating algorithm of the MT6582 chip, which is based on the A7 and includes 4 computing units, the frequency of which varies from 600 MHz to 1.3 GHz. In idle mode, this processor device can only have one computing unit, and it operates at a minimum possible frequency at 600 MHz. A similar situation will occur when a simple application is launched on a mobile gadget. But when a resource-intensive toy optimized for multi-threading appears on the task list, all 4 blocks of program code processing at a frequency of 1.3 GHz will automatically start working. As the CPU heats up, the hottest cores will lower their clock speed or even shut down. On the one hand, this approach ensures energy efficiency, and on the other, an acceptable level of chip performance.

Cache memory

Only 2 cache levels are provided in the ARM Cortex A7. Characteristics semiconductor crystal, in turn, indicate that the first level is necessarily divided into 2 equal halves. One of themshould store data, and the other - instructions. Total size cache at level 1according to specifications can be equal 64 KB. As a result, we get 32 ​​KB for data and 32 KB for code.The 2nd level cache will be stuck in this case e from specific model CPU. Its smallest volume can be 0 MB (that is, absent), and its largest can be 4 MB.

RAM controller. Its features

Built-in controller random access memory Comes with any ARM Cortex A7 processor. The characteristics of the technical plan indicate that it is designed to work in conjunction with LPDDR3 standard RAM. The recommended operating memory frequencies in this case are 1066 MHz or 1333 MHz. The maximum size of RAM that can be found in practice for this chip model is 2 GB.



Integrated Graphics

As expected, these microprocessor devices have an integrated graphics subsystem. The ARM manufacturer recommends using in combination with this CPU graphics card own development Mali-400MP2. But its performance is most often not enough to unlock the potential of a microprocessor device. Therefore, chip developers use more powerful adapters in combination with this chip, for example, Power VR6200.

Software features

Three types of operating systems are targeted at ARM processors:

Android from search giant Google.

iOS by APPLE.

Windows Mobile from Microsoft.

All other system software has not yet received wide distribution. As you might guess, the largest share in the market for such software is occupied by Android. This system has a simple and clear interface and entry-level devices based on it are very, very affordable. Up to version 4.4 inclusive, it was 32-bit, and with 5.0 it began to support 64-bit computing. This OS runs successfully on any family of CPUs RISC architectures, including ARM Cortex A7. Engineering menu- This is another important feature of this system software. With its help, you can significantly reconfigure the capabilities of the OS. This menu can be accessed using a code that is individual for each CPU model.

Another important feature of this OS is the installation of all possible updates automatically. Therefore, even new features may appear on chips from the ARM Cortex A7 family. Firmware can add them. The second system is aimed at mobile gadgets from APPLE. Such devices mainly occupy the premium segment and have corresponding levels of performance and cost. The latest OS, Windows Mobile, has not yet become widespread. There are devices based on it in any segment of mobile gadgets, but the small amount of application software in this case is a limiting factor for its spread.



Processor models

The most affordable and least productive in this case are single-core chips. The most widely used among them is MT6571 from MediaTek. A step up are dual-core ARM Cortex A7 CPUs. Dual Core. An example is the MT6572 from the same manufacturer. An even greater level of performance was provided by Quad Core ARM Cortex A7. The most popular chip from this family is the MT6582, which can now even be found in entry-level mobile gadgets. Well, the highest level of performance was provided by 8-core central processing units, to which MT6595 belonged.

Further development prospects

You can still find mobile devices on store shelves that are based on a semiconductor processor device based on 4X ARM Cortex A7. These are MT6580, MT6582 and Snapdragon 200. All these chips include 4 computing units and have an excellent level of energy efficiency. Also, the cost in this case is very, very modest. But still better times this microprocessor architecture is already behind us. The peak of sales of products based on it fell in 2013-2014, when there was practically no alternative to it on the market of mobile gadgets. And in this case we're talking about how about budget devices with 1 or 2 computing modules, and with flagship gadgets with an 8-core CPU. On this moment it is gradually being forced out of the market by “Cortex A53”, which is essentially a modified 64-bit version of A7. At the same time, it retained the main advantages of its predecessor entirely, and the future certainly belongs to it.



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

Of course, a significant event for the world of mobile devices was the emergence of the ARM Cortex A7 microprocessor device architecture. The best proof of this is that devices based on it have already been successfully sold for more than 5 years. Of course, now the capabilities of an A7-based CPU are no longer enough even to solve mid-level problems, but here is the simplest program code it still operates successfully on such chips to this day. The list of such software includes playing videos, listening to audio recordings, reading books, surfing the web, and even the simplest toys in this case will start without special problems. This is precisely what is emphasized on the leading thematic portals dedicated to mobile gadgets and devices by both leading specialists of this kind and regular users. The key disadvantage of the A7 is the lack of support for 64-bit computing. Well, its main advantages include the ideal combination of energy efficiency and performance.



Results

Of course, Cortex A7 - This is a whole era in the world of mobile devices. It was with its advent that mobile devices became accessible and quite productive. And the fact that it has been successfully sold for more than 5 years is further confirmation of this. But if at first gadgets based on it occupied the middle and premium segments of the market, now only the budget class remains behind them. This architecture is outdated and gradually becoming a thing of the past.

Although the new system on a chip A7 from Apple, which is the basis, did not receive an increased number of cores, its performance turned out to be higher than that of its closest competitors. They decided to figure out what the secret of the new high-performance chip is Chipworks, at the same time studying the coprocessor M7.

We have already reported that the manufacturer new system on a chip for Apple performed Samsung. Although Apple wants to move chip production to facilities TSMC, but this will not happen until the beginning of next year. Manufactured new processor based on 28 nm technology and operates at a frequency of 1.3 GHz. For comparison, flagship processors Intel generations Haswell made using 22 nm technology.

Transistor density in A7 (left) and A6 (right)

First of all, the increased transistor density in SoC A7 attracts attention, increasing by 7.3%. Now the distance between adjacent transistors is 114 nm. For comparison, in A6 this figure was 123 nm. Thus, the number of transistors in the A7 is approaching one billion. By the way, the Samsung processor used in the Galaxy S IV Exynos 5410, manufactured using a similar technical process and contains as many as eight cores, but in this moment is already behind the A7 in synthetic tests.

A7

In addition, the world's first 64-bit mobile system The chip contains a 4-core PowerVR G6430 GPU. Sixth generation graphics from Imagination Technologies are used for the first time in commercial product and appears to be capable of providing new visualization capabilities on mobile devices. The GPU supports OpenGL 3.0 and DirectX 10. So the benchmark game will probably be just the first sign.

M7

Next, the M7 coprocessor came under the scrutiny of Chipworks, the functions and capabilities of which we have already discussed. Responsible for its production NXP and it is made on the basis ARM Cortex-M3. M7 operates at a frequency of 180 MHz. As previously reported, the coprocessor collects and processes information from the compass, gyroscope and magnetometer, relieving these responsibilities from the A7.

Such serious power in every sense is hidden in the glass-aluminum depths of the iPhone 5s. The only thing that upsets us is the lack of software capable of fully utilizing the computing and graphic power of the new system on the A7 chip. [

Designed in Apple and created using technological Samsung solutions, this processor built on the “system-on-a-chip” principle.

In contact with

That is, all the components for implementing computing processes during operation are contained in one single silicon wafer mobile gadget: microprocessor for general processing, graphics core, cache, memory controllers and other interfaces. Like Intel, Apple owns a 10% stake in the British developer of advanced semiconductor technologies, Imagination Technologies. The latter does not have its own production facilities and only designs new microprocessors in accordance with the customer’s design and specifications.

Therefore, it is not surprising that the new A7 consists of 2 cores of the main CPU and 4 cores of the GPU graphics module, built on the basis of PowerVR Series 6 clusters, version G6430. Plus experts from Chipworks focus on a separate block called “Security Enclave” - a protected memory segment intended for system operation.
Based on the results of the preliminary “opening” of the A7, we can draw a cautious conclusion - the new product is built according to the principles of the ARMv8 architecture and is not compatible with old version ARM A53/57. Technologically, the chip itself is supposed to be created using 28nm technology with an active metal gate. That is, in some ways, this is an analogue of those devices developed by Samsung for its own Exynos processors, which are installed in . The processor core is equipped with 256 KB of L1 cache and 1 MB of L2 cache, but it is not yet clear whether part of the system RAM, whose capacity according to the specification is 1 GB, is used when operating the processor.
But it is clear that the 4 cores of the new GPU are much better than the 3 cores in the old A6 chip. Studying the arrangement of elements on the plate, it can be noted that two main cores and cache memory occupy 17% of the total area, and 4 GPU cores and general logic another 22%. As for the notorious novelty, the fingerprint scanner and the protected memory area for storing them, it is problematic to assess its role in the chip structure - there is nothing to compare it with. On the one hand, 3 MB is a bit much, on the other hand, there is a need to store several prints, in different orientations relative to the sensor itself, and this requires free space memory. Therefore, the A7 wafer houses a rather bulky SRAM module, right above the cluster of GPU cores.

However, the design of the A7 chip layout is similar to its predecessors - A6 and A5, but at least, with regard to the location of interfaces for interaction with the built-in camera, USB and touch display. And Touch ID, admittedly, is perhaps the most reliable, elegant and innovative security solution today. Accordingly, the AuthenTec development and analysis itself technical solutions, used by them, are worthy of a separate review - wait, Chipworks will do this soon.
By the way, analyzing own developments Samsung is in the same direction, we have to admit, before introducing fingerprint scanners into its devices on a serial basis. As they themselves recently stated in an interview with The Korea Herald, “the technology is not yet developed,” which means it will take at least a year before it is implemented in real models. And this is not the only thing over Samsung - for example, if the main A7 processor is still produced in Korean factories, then the new M7 motion coprocessor is rebranded NXP LPC18A1. Chipworks also found out that both cameras are for iPhone, basic iSight with an Exmor-RS matrix from Sony and front-facing FaceTime using OmniVision technology, as well as an accelerometer are manufactured by Bosch.

Hello everyone, dear users of the best mobile portal Trashbox. If you are interested new smartphone from Apple called iPhone 5S, as well as the world’s first 64-bit mobile processor used in the new product, then in today’s article I will tell you about it. Let's find out what the Apple A7 is and how it works. The most interesting, as always, read under the cut.

Apple A7 is a new processor from Apple. It is the world's first 64-bit mobile ARM chipset. Made using 28 nanometer production technology. Official manufacturer of the 64-bit Apple A7 processor - Samsung company. Uses the ARMv8 instruction set. The number of cores is two, clock frequency is 1.3 GHz. According to Apple, the new chip is twice as productive as the Apple A6 processor, which is currently installed in iPhone smartphone 5. Of course, increasing the processor bit rate does not provide any significant increase in performance, so Apple doubled the number of registers. Thus, theoretically, after this, the increase in overall productivity can range from 33 to as much as 100 percent.

It is known that the new Apple A7 processor is comparable in computing power with desktop solutions. If you compare the new 64-bit chip with the very first generation of Apple processors, it provides a 40-fold increase in overall performance, and a 56-fold increase in graphics performance. It has been officially confirmed that the 64-bit Apple A7 processor has two processing cores, and not four, as previously thought. The integrated PowerVR G6430 GPU is responsible for graphics processing. Reviewers note that the Apple A7 is one of the fastest mobile processors currently. Despite “only” two computing cores, the new chip is superior in performance to a quad-core processor in a number of tasks Qualcomm Snapdragon 800.

From a computer science course in grades 10-11, we know that an arithmetic-logical unit, or ALU for short, is responsible for performing operations with numbers in the processor. The processor has registers, so-called memory cells. They serve as input and output information for temporary storage. From some registers, numbers enter the arithmetic-logical device, and go to others. The sources of information in this case are the drive, RAM, processor cache, graphics chip, as well as modules, sensors and sensors. Depending on the bit depth of the processor, registers are capable of storing numbers of different bit depths. A 64-bit wide register can store any number within 18 quintillion.

In the new mobile operating room iOS system 7 system code, drivers, and libraries work in 64-bit mode, as expected. However, there are no applications that really effectively use the new 64-bit Apple A7 processor, but, according to the manufacturer, they will appear later. Of course, not all applications will require the new 64-bit architecture, but it will be useful for graphics-heavy games and photo and video processing. Moreover, thanks to OpenGL support ES 3.0, graphics performance in games will be noticeably higher.

In addition to twice the performance, another feature of the mobile 64-bit processor is the ability to work with large volumes random access memory. As for the 32-bit processor in this case, it is capable of accessing no more than four gigabytes. The Apple A7 processor can access 16 exabytes or 16777216 terabytes of memory - this is an incredible amount.