Comparison Of RISC And CISC Processor Architectures For Operating Systems

Abstract

This paper looks at the RISC and CISC computer processor architectures in the context of operating system issues such as performance and architecture. RISC is an architecture that uses simplified instructions to execute operations in a single clock cycle, while CISC is an architecture that aims at completing tasks in as few lines as is possible and so uses the MULT system which is a complex instruction, while RISC breaks down MULT into simple instructions. For this reason, RISC performs much faster (between 2 and 4 times) when compared to CISC when running a program such as an Operating System instruction. Because of simplicity, RISC has an advantage of speed; it performs fast, and is cheaper and easier to produce; but this also raises ethical issues as RISC focuses on performance and not protection while leading to increased e-wastes as every new generation of RISC processors have significantly large and better performance over previous generations. CISC makes micro programming easy and does not require a complicated compiler; it also uses fewer instructions for task execution. However, it has the limitation of speed; its comparatively much slower and complex because it constrains instructions as a subset of previous generations, leading to complex architectures. It can slow down an OS because different instructions need different clock times for their execution. Setting condition codes is required in CISC and these can take a lot of time, and have to be examined

Each processor is built with an ability to execute a given set of instructions to perform a limited set of fundamental operations. The processor has an instruction set architecture necessary for creating programs at the machine level to perform any logical and mathematical computations. This instruction set is embedded within processor and serves as the bridge between the hardware and software.  High level language is translated into machine level language using a compiler. If there is an increase in the number of complex instructions in the processor instruction set, the processor working slows down because there is increased complexity in instruction decoding; this also consumes more time. The most important factor that impacts software and overall computer performance is the design of the processor instruction set; it impacts how operating systems are designed and how they run on the computer processor. This is due to the fact that all software applications and operating systems  are programmed within the processor instruction set boundaries. So for every processor, a unique instruction set is employed so that one processors’ machine language programs will not run on a different processor. Computer use processors to carry out computations; these CPUs have distinct design philosophies, namely RISC (Reduced Instruction Set Computer) and CISC (Complex Instruction Set Computer). The main goal of the CISC architecture is the completion of tasks in as few assembly lines as possible. To achieve this, the processor hardware is built so it can understand and execute a series of operations; it comes prepared with a specific set of instructions (MULT). Upon execution, the MULT loads the 2 values into separate registers, multiplies that operation within the execution unit, and stores the outcome in the appropriate register. In this way, CISC completes an entire multiplication process using a singe instruction. MULT directly operates in the memory banks of computers and the programmer is thus not required to explicitly call any storing or loading instructions. In the RISC approach, only simple instructions that are executable in a single clock cycle are used, so the ‘MULT’ command described in CISC above is divided into three commands that are separate; ‘LOAD’ that moves data to the register from a memory bank, ‘PROD’ that finds two operand products located in the registers, and ‘STORE’ that moves data to the memory banks from the register. CISC has a focus on hardware and can perform complex multi clock instructions (Blem, Menon & Sankaralingam, 2013). RISC on the other hand, has a greater focus on software and operates in a single clock cycle to execute tasks. The operating systems are designed so as to make the best use of the underlying processor architecture; its performance in terms of memory addressing and architecture (layering), as well as its implementation is directly impacted by the processor it runs on. The performance of operating systems is also impacted by the processor architecture in the context of the ISA (instruction set architecture). A CISC processor has several specialized instructions though some are rarely used practically in operating systems while a RISC processor simplifies things through the efficient implementation only of the instructions that the operating system uses frequently; RISC implements the less common operations as subroutines. This approach results in the extra processor execution time compensated for by their infrequent usage (Burger et al., 2004). These design philosophies have their merits and demerits in terms of computer performance and operating system architecture and performance

Background

Advantages

The different architectures have their merits; CISC has advantages in micro programming; this becomes as easy to implement as assembly language with RISC. Further, micro programming is far less expensive compared to hard wiring control units. CISC machines have upward compatibility allowing new computers to run older programs as the new computer has a set of instructions contained in the earlier computers. It uses fewer instructions for task implementation, an advantage when the main memory is slow. It does not require a complicated compiler since instruction sets for micro programs can be written to match up to high level languages.

The RISC architecture has a number of advantages as well; its main advantage is speed because it has a simplified instruction set that enables super scalar pipelined design; this makes them achieve between 2 and 4 times the CISC processor performance when comparable semi conductor technology as well as similar clock speeds are used. RISC processors use significantly less chip space as well as other functions such as floating point arithmetic units and memory management units; these can be placed in the same RISC chip, reducing space use and power consumption. More parts can thus be placed on the same wafer chip, resulting in reduced cost of processor chips. RISC processors are far simple, compared to corresponding CISC processors, and this makes their design quick. This implies their design can make use of new technological advances when compared to CISC resulting in bigger performance leaps between processor generations.

The CISC philosophy has problems; the chip hardware and instruction set for CISC processors have become more complex with every subsequent computer generation because it began with generations of processors contained in every new version as a subset. Because it worked based on the philosophy of storing as many sets of instructions as possible in memory so that as little space as possible is wasted, they now have the disadvantage of having different instruction sets taking different amounts of clock time in execution, chiefly because of  having long individual instructions of any length; this slows down machine performance and operating system performance. The philosophy has many specialized instructions, but which are not frequently used, and their existence is not justified as operating systems use just 20% of available instructions. Single codes n CISC are set as an instruction side effect; setting conditions take time and the code must be examined by programmers before they are changed by subsequent instructions.

RISC also has its disadvantages; transitioning operating systems fro CISC based architectures to RISC based architectures has pitfalls. The RISC processor performance depends greatly on the code it executes, a poor job in instruction scheduling can lead to the processor taking time to execute, leading to processor stalling. Because of complications in scheduling rules, high level languages are used more (such as C++), thus leaving instruction scheduling to the compiler.

Legal and Ethical

Von Neumann’s assumptions on computers has led to the ICT community failing to understand that there can be problems in the processor architecture that cause risks and performance issues; fr instance the Intel 80386 and the 80486 processors had floating point arithmetic bugs.  Given that the dominant consideration is performance, concepts such as safety and control are not given their due considerations. CISC computers have been reduced to sets for frequent efficient execution and processes necessary for safeguarding the memory of a processor or OS/ program so other programs such as malware  DO not belong to these extended instructions. This risk is magnified by RISC because it reduces levels of protection (Berleur and Brunnstein 2001). Further, because of fast development, RISC based computers which are common are used and with each new faster generation is increased electronic waste that overloads the environment, according to Balakrishnan, Anand,  & Chiya (2016)

Advantages

Conclusion

Each processor is built with the capability to execute a given set of instructions to perform a limited set of fundamental operations. Processors have instruction sets that are a bridge between hardware and software, and their design determines the computer architecture. Two architectures are used; RISC, and CISC. The main aim of the CISC architecture is the completion of tasks in as few assembly lines as possible by executing a series of operations. It has advantages in microprogramming and upward compatibility and  uses fewer instructions for task implementation, an advantage when the main memory is slow. However, it has limitations because its slower than RISC, complex to construct and they can slow machine and OS performance due to processing of instruction at different clock speeds. RISC is another architecture that implements simplified instructions in a single cycle and one of its advantages is speed, it performs 2 to 4 times better than a comparable RISC computer. CISC is hardware focused while RISC is software focused, giving RISC a disadvantage of depending on how the codes it executes are written. There is an ethical issue in that the transition from CISC to RISK has increased security risks in computers; there is more focus on performance and protection is not given due attention. Further, because RISC is widely used, each new generation has high performance that renders previous generations ‘outdated’, leading to massive e-waste.

Abstract

This paper looks at data communications in the modern world and how it has grown as well as its benefits and disadvantages. Further, the concept of data encryption for data at rest or in transit is discussed. Data communications has spawned many industries, made the world a global village, enabled easy and cost effective communication around the world in an instant, and opened up opportunities. However, data communications has demerits, including risk of data loss and abuse of such data, such as through hacking for malicious purposes. Data encryption solves some of the disadvantages and problems of data communications, including enhancing security for the data, but has its own disadvantages, including risk of data loss should an encryption key be lost and slowing down system performance. Data communications and data encryption pose some serious ethical and legal issues. On one hand, private data must remain safe and secured according to laws in many countries. An ethical issues arises when a criminal takes advantage of data privacy and protection laws to further criminal or anti social activity such as terrorism. Another ethical issue is when private data is breached or used without permission form the owner for commercial purposes, such as collecting and selling the browser data of a person for commercial gain.

Data communications is the exchange of data between a receiver and a source using communications and computing technologies ; data communications can be said to be local when the devices are found in the same geographical area such as one  building. The device transmitting data is the source and the one receiving data is the receiver. The aim of data communications is both to transfer it (data) and also maintain the data during the transmission/ exchange process; however data communications does not entail generation of the data. Digital or electronic data can be moved from one node to another regardless of where the nodes are geographically located, the contents of the data, or the medium used. Data communication entails several technologies and techniques  whose main objective is t enable all forms of electronic communication. The technologies include computer networking, telecommunications, and satellite/ radio communication. Data communications can only occur if there is a medium for transmitting data between the source and the receiver (the nodes); of which media can be fiber optic cables, copper, or wireless signals. Most of the computing today involves data communications; from a computer connected to a Wi-Fi to sending and receiving e-mails, using a cell phone, and cloud computing, among other forms of data communications (Sengupta, Kaulgud,  & Sharma, 2011).  One of the biggest assets businesses have and among the most important modern day activity is data and data communications, respectively. Some of the data is highly sensitive, form financial transactions to private text messages and personal health and financial records that must be kept safe and secure. In the process of transmission, the data can be exposed to exploitation, such as hacking by malicious users who can seal personal data such as credit card information and cause financial losses or even identity theft. Data can be at risk while at rest (in storage) or in transit (during the process of data communications). Encryption is a concept in cryptography that involves the process of information/ data encoding in a way that only people that are authorized (with a decoding code) can access the data. While encrypting data does not necessarily prevent interference with the data, a would be interceptor is denied access to the intelligible content (Yu & Cai, 2003). The data or message (plain text) is encoded through encryption algorithms (which is the cipher) to generate cypher text that can be read or viewed only when decrypted. encryption entails the use of pseudo random keys for encryption that an algorithm generates and the intended recipient of the data communication can then use the provided key for decrypting the data/ message. Encryption is designed to protect data when at rest (in storage) such as in a database or on a hard drive and when the data is in transit such as sending data to a cloud storage or sending e-mail. Two main types of data encryption exist; symmetric key encryption and public key encryption. Symmetric key encryption (also called private key) entails using a similar key for encryption and decryption; the source and recipient nodes/ parties must both have and use the same key to achieve secured communication. Public key encryption, on the other hand, entails the publication of the encryption key so anyone can use it for encrypting messages, however, only the recipient node/ party can access the decryption key that allows access to the information (Zhang et al., 2009). Militaries, governments, corporations, and individuals use encryption for securing data both when it is a rest and during transit. In data communications, encryption can be used in whole disk encryption, file or folder encryption, database encryption, multiple user folder encryption, application level encrypting, e-mail encrypting, and encrypting of Internet/ network traffic.

Disadvantages

the main advantage of encryption of data in data communications is data security; people and organizations, including governments send information over media that can be intercepted and used for malicious purposes. The increased use of the cloud means that people and entities increasingly surrender the physical control over their data to cloud service providers where resources, including storage space, is shared. Encryption allows the entities to maintain control, security, and privacy over their data. Encryption helps organizations and people move to the cloud and with the keys of the encrypted data, decommissioning provision becomes very easy. Secure multiple tenancy is achieved in the cloud, courtesy of encryption and even service providers cannot access one’s data. Encryption also enables entities to comply with regulations on data security and privacy. Data communications has immense benefits; some industries today exist solely because of the possibility of data communications. Technology giants such as Apple, Cisco, Facebook exist solely because of the possibilities of data communications. The advent of data communications has made it easy to send messages/ data fast and cost effectively; a TV crew in a remote African region can quickly relay news to their head office in Europe for broadcasting in a few minutes, and cost effectively too. Cloud computing, which has immense benefits, is possible courtesy of data communications. People can collaborate on a global level in a project in real time because of data communications, while decision making becomes fast and informed due to data communications (Rajagopalan & Varshney, 2006).

However, data communications skill has disadvantages; it eliminates or drastically reduces the face to face communication, and it is not a very good substitute, especially among humans so social skills are lost. Data communications can be expensive when a new technology is being installed in a large geographically dispersed organization, such as linking them with fiber optics. One of the biggest disadvantages in data communications is the risk of losing privacy and security,or complete data loss.  Data remains exposed whether at rest or in transit, and has led to a whole new criminal industry of hackers and malicious users who steal/ breach data and sell it or as fr ransom to avoid exposing such data.  While encryption offers several benefits, one of its bigger disadvantages is that  it uses keys which implies that the data security in essence becomes the security of the key (encryption key). If that key is lost, then the data is effectively lost; this data can be crucial, such as an invention or classified information. The computational costs associated with data encryption and decryption can be costly in some applications in data communications, such as cellular communication.  It is also a very complex process that adds administrative tasks to an organization.  Some encryptions, such as full disk encryptions result in reduced system performance and a poor encryption implementation can give a false sense of security when in fact, the data is highly exposed to attacks (Rajagopalan & Varshney, 2006)

data communications entails sharing/ sending data such as e-mails; for administrators, there is the ethical issue of snooping in o this communication or not, especially if the said persons are suspected of clandestine activities. There is the legal issue f information security, such as personal information privacy and security acts that various entities must deal with. There is also the issue of some entities collecting personal information, such as browsing history and passing off this information to advertisers for commercial gain, without explicitly seeking the permission of the concerned person. There is also an ethical issue when data is highly protected and secured, such as using sncryption and various data privacy laws; the information being exchanged could be by terrorists planning to cause massive harm to society; should such data be protected?  

Conclusion 

The present world almost survives and advances due to the possibilities created by data communications; people ca watch global news, get education, be entertained, and share and exchange information across the globe in an instant and at very low rates. Data communication has ed the world to becoming a global village that has brought people, cultures, countries, closer and closer; a person in Australia can have a real time video chat with a friend in the United States or Europe. With advances in data communications have developed risks and disadvantages of data communications, including information abuse, theft of information, and inspired an entire criminal industry of hackers and malicious attackers that steal/ breach data for all kinds of purposes, including identity theft. These disadvantages have led to the development of encryption where algorithms are used to convert data into unreadable forms while in storage and in transit; providing a first layer of data protection and security. However, encryption has its demerits; losing an encryption key means the data is lost; it can slow system performance, and is very costly and complex to computational resources. Data communications and encryption of data while at rest and in transit also have various legal and ethical implications. Laws exist on data security and privacy to which organizations must adhere to. Some entities collect personal information and sell it off for profit without information the owner of that data.

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