A Review of ARM Processor Architecture History, Progress and Applications

: Globally, over 50 billion ARM architecture based embedded chips of 32-bit and 64-bit instruction set architecture are commonly used and produced in quantity perspective since 2014. In our daily life most of the people uses and depends upon a penalty of electrical and automotive devices which have now become an essential part of their daily life. Due to that reason embedded processors are used to build such devices which takes less silicone-space, provides efficient processing and less power.

As compared to CISC architecture which is more emphasis on hardware RISC architecture based processor has required fewer transistors and less silicon area. [12] In order to enhance the performance functions (floating point hardware, memory management functions, cache memory) of system a huge area of board is left free in RISC CPU Which brings improvement in cost, power consumption, and heat dissipation [4].

ii. FEATURES OF ARM ARCHITECTURE
When the primary ARM processor was introduced, only instances of reduced instruction set computing processor (RISC) were the Stanford MIPS and Berkeley reduced instruction set computing Processor. The ARM design has taken some of the features from Berkeley RISC design like a uniform register file load store architecture, 32-bit fixedlength instruction, and 3-address instruction formats [5].ARM architectural licensing provides the facility of designing their own processor cores with the help of instruction set of ARM. iii.

ARM ARCHITECTURE
Improvements in architecture of RISC allows Arm processors to achieve balance in less size of code, high performance, lowering the power consumption, and less region of silicon. Arm architecture has progressed with passing time, incorporating many levels of architecture in its history which are as follows [8].
ARM produces an entire family of CPUs that share shared (ISA) instruction sets architecture and programmer's models which have backward compatibility. CPUs applying the Arm Architecture follow to a particular series of the architecture [11]. Which are:  ('A') p r o f i l e or A r c h i t e c t u r a l p r o f i l e , is used for high performance industries such as mobile and enterprise.  ('R') profile or Real-Time profile, used for embedded applications, healthcare, automotive and industrial control.  ('M') Microcontroller pr ofi le or profil e , used in the microcontroller, wearable, Internet of Things, single processing like controlling motor and power, sensor fusion [12].
The latest architecture Armv8 series architecture has three variations of the architecture relating processors aiming different markets:  Latest generation of Arm architecture in Aprofile is Armv8-A It indicate the overview of a 64-bit architecture beside the firm 32bit architecture, and allows multiple stages of AArch32 and AArch64 support.  Latest generation of Arm architecture in Rprofile is Armv8-R .This architecture involved a Memory Protection Unit (MPU) and deterministic memory structure and supports the A32 and T32 instruction-sets architecture [13].  Latest generation of Arm architecture in M-profile is Armv8-M.its mostly used in low cost embedded systems.it also sup-port to other profiles by different exception handling technique and bring sup-ports to T32 instruction sets architecture [14].  [3] iv.

ARM INSTRUCTION SET
ARM processors supports following 3 type of architecture instruction sets. The main support of A64-IS is the architecture of ARMv8-A and it Important feature are following:  5-bit clean decoder table based register specifiers.  A32 and T32 Instruction  64-bit general purpose registers accessible at any time (total = 31).  For improvement in performance and energy of general purpose registers modal banking is not implemented.  Dedicated, zero-register available for ut- most instructions [6] v.

ARM PROCESSOR MODES OF OPERATION
ARM used seven operating modes .Respectively has access to its individual stack space and a different subset of registers. [15] vi.

IMPORTANT REGISTERS
The internal hardware device of CPU is Register which not only stores binary data but also can be accessible rapidly than other locations in RAM. 13 [8] register for SP and LR banked. Seven register of FIQ mode for R8-R12 banked, LR and SP. Two registers of monitor mode for SP and LR banked. Six Saved Program Status Registers (SPSRs), 1 exception mode [16]. [19] vii.

APPLICATION DOMAINS OF ARM PROCESSOR
Following are the application series of Cortex processor.
 ARM CORTEX-A SERIES PROCESSORS Cortex-A series, deliver a range of solutions for devices responsible for the tasks of complex computing, like: rich Operating System (OS) hosting platform, and support of different software applications [17] The 32-bit and 64-bit series of RISC ARM Processor cores is of ARM Cortex-A which are used for applications consisting of 32-bit ARM Cortex (A5, A7-A9, A12, A15, A17) and 64-bit ARM Cortex (A-53, A57,A72)[10] [18].

Application includes
 Server  Automotive  Embedded  Smartphones  Intelligent devices in your home  Large-screen compute  Table 1 ARMv8-A Architecture featues comaparison [1]  ARM CORTEX-R SERIES PROCESSORS Cortex-R series, deliver fast and deterministic pro-cessing and high performance, while meeting chal-lenging real-time constraints in a range of situa-tions. They combine those features in a perfor-mance, power and area optimization, making them the trusted choice in consistent systems demanding high error resistance [13]. Important series of cortex-R processors are Cortex-(R4,R5,R7,R8) and most advanced processor of this series is Cortex-R52 [7]Application includes: (177)   [3] viii. CONCLUSION ARM architecture, blending of the simple hardware instruction sets that's stranded in RISC ideas but recalls some of key CISC features, such as improved code density, has made the ARM more power efficient and result in small silicone size. It is simple pipeline construction which is low cost and adds efficiency to modern VLSI technology and embedded applications and these technologies permits huge number of further components of system which can be incorporated on the same chip. The current low end ARM core is ARM9TDMI which is used excessively by a range of applications and also supports ARM 32-bit and Thumb instruction set of 16 bits which allows the user to tradeoff between density of high code and high performance. Most of the smartphones and electronics gadget which is the part of our daily life are now using this power. ARM processors towards ARM9 uses pipeline of 5 stages like: fetching, decoding, execution, data memory access and register write. ix.