Introduction
The history of computer technology is characterized by surprising breakthroughs in the last few decades. Computer technology has brought about radical changes in the world since the time of the computer’s appearance. It has entirely altered the workflows, society, and ways of living. The last 25 years have been fruitful in computing performance optimizations by theories like Reduced Instruction Set Computing (RISC), pipeline processing, caching memory, and virtual memory, which led to improved system performance. This paper seeks to expound on the increasing levels of these principles over the years, considering the changes they are undergoing to improve system operations.
Evolution of Concept
Reduced Instruction Set Computing (RISC)
One of the design breakthroughs in the 1980s was RISC (Reduced Instruction Set Computer), whose primary focus was to simplify CPU operation by reducing the complexity of instructions. RISC implements this task as opposed to CISC, which has different and very complex instructions. Based on complex instruction sets, CISC architecture gave rise to the RISC (Reduced Instruction Set Computing) architecture developed a decade later. In the case of RISC processors, fewer cycles are required for the execution of an instruction, which in turn improves system performance by ensuring quicker execution. RISC processor architecture has improved during this period, adding new functions such as superscalar execution, out-of-order execution, and speculative execution. These features have made the system run faster (Mitchell, 2001). The shift of paradigm led to faster execution speed of the system and its overall performance. Since its inception, RISC processors have been enriched with many advanced features, such as superscalar execution that enables concurrent execution of multiple instructions and out-of-sequence execution, allowing the processor to reorganize instructions to increase performance.
Pipelining
Instruction pipelining started in the 1960s, which breaks up the execution of instruction into sub-tasks that can be processed in a parallel way. Therefore, it increases the execution throughput. Pipelines, derived from the idea of assembly line manufacturing, divide instruction execution steps into sequential stages, one following the other. Every stage is dedicated to a certain operation, implying that several commands can be performed in parallel (Davis, 1977). This twofold role of staff members eliminates idle time, and thus, it increases pace and efficiency. Pipelining was first applied to the mainframe. However, it has been considered a modern processor architecture design base concept. Instruction-level parallelism and branch prediction have been applied as high-level techniques to structure the pipelines so pipeline stalls are minimized. So, better performance is achieved (Davis, 1977). Some challenges encountered at the initial pipelining stage were pipeline stalls due to data dependency and wrong branches. However, these mechanisms are being introduced with assurance for forwarding and branch prediction, and pipelining has become necessary for modern processors.
Cache Memory
To reduce latency, the processor has a cache or buffer with the commonly used information between the memory and the main processor. The cache memory works as an intermediate that is very swift between the processor and the main memory, and it stores the most used data and instructions, which are temporary. Earlier, caches were smaller, but big cache hierarchies were still developed with the help of progress in semiconductor technology. Introducing techniques like pre-fetching, cache associativity, and cache coherence protocol has significantly improved system performance and speeds (Mitchell, 2001). Multiple cache levels are used to search for the spatial locality to increase memory access speed.
Virtual Memory
Virtual memory is the technique that programmers implement in a computer to increase access to disk space and to make effective memory management and multitasking. It does this by transparently swapping the data between these components, making it seem like you have endless RAM (Mitchell, 2001). Previously, the virtual memory system was dominated by the disk I/O, which can be a performance bottleneck. Despite this, memory innovations, such as demand paging, memory mapping, and page replacement algorithms, have made the operating system create virtual memory with disk access and high system response (Davis, 1977). These designs result in increased systems performance and enable modern computers to multitask and cope with memory-intensive applications.
Current Trends
The development of computer technology is still being studied and explored. One of the significant characteristics of heterogeneous computing architectures is the merger of high-performance CPUs and specialized accelerators like GPUs, FPGAs, and AI accelerators, which is part of the trend. By linking the good qualities of different processing units, this technology can also boost the performance and efficiency of power consumption (Mitchell, 2001). The opposite trend is that the power efficiency and scalability of the processor structure get increasingly important. With the proliferation of smartphones and servers, the trend has shifted where processors should serve high power but consume low power. Solutions, including DVFS, heterogeneous multi-core architecture, and complex energy management, have been proposed to handle the challenges.
Moreover, memory technologies like non-volatile memory (NVM) and high bandwidth memory (HBM) have changed the idea of processing systems. NVM has both the benefits of speed and persistence, similar to HDDs and SSDs, but it is more reliable, unlike the HBM, which is a high-speed and power-consumptive memory type used for demanding tasks.
Conclusion
The highlight of the notions discussed is the evolution of the cache memory, which has a tremendous effect on the speed and performance of the system. Cache memory is crucial in reducing the performance gap between processor and main memory. Therefore, letters are processed faster, making the whole system more efficient. Along with the advancement in cache memory design and concepts like heterogeneous systems and power-efficient design, computing will pave the way for the next wave in technology progression.
References
Davis, R. M. (1977). The history of computers and computing Science, 195(4283), 1096-1102. https://www.science.org/doi/abs/10.1126/science.195.4283.1096
Mitchell, M. (2001). The two issues of life and evolution inside the computers. From the history and philosophy of the life sciences, 361 to 383. https://www.jstor.org/stable/23332520
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