In addition references to arrays/structures required a previous reference to their index or pointer, which again is usually a local scalar. The results showed that majority of references are single scalar variables. Researches also studied the dynamic frequency of occurrence of classes of variables. These results are instructive to the machine instruction set designers, indicating which type of statements occur most often and therefore should be supported in an “optimal” fashion.įrom these studies one can observe that though a complex and sophisticated instruction set is available in a machine architecture, common programmer may not use those instructions frequently.
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Tanenbaum, A "Implication of Structured Programming for machine architecture ", Communication of the ACM, March 1978. Patterson, D and Sequin, C "A VLSI RISC ", Computer, September 1982.
SUPPOSE THAT A RISC MACHINE USES 5 REGISTER WINDOWS SOFTWARE
Knuth D "An Empirical Study of FORTRAN programs ", Software practice and Experience, Vol. Huck, T "Comparative analysis of computer architectures", Stanford University Technical Report Table8.1 : Relative Dynamic Frequency of High-Level Language operation
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The Table 8.1 includes key results, measuring the appearance of various statement types during execution which is carried out by different researchers. This suggest that the sequence control mechanism of the instruction set is important.Ī variety of studies have analyzed the behavior of high level language program. These statements are implemented in machine language with some sort of compare and branch instruction. There is also a presence of conditional statements (IF, Loop, etc.).Assignment statements predominates, suggesting that the simple movement of data is of high importance.Execution sequencing: This determines the control and pipeline organization.Ī variety of studies have been made to analyze the behavior of HLL programs.Operand Used: The types of operands and the frequency of their use determine the memory organization for storing them and the addressing modes for accessing them.Operation Performed: These determine the functions to be performed by the processor and its interaction with memory.The instruction execution characteristics involves the following aspects of computation: To reduce the gap between HLL and the instruction set of computer architecture, the system becomes more and more complex and the resulted system is termed as Complex Instruction Set Computer (CISC).Ī number of studies have been done over the years to determine the characteristics and patterns of execution of machine instructions generated from HLL programs. Provide support for even more complex and sophisticated HLLs.Improve execution efficiency, because complex sequences of operations can be implemented in microcode.Such complex instruction sets are intended to. As a result the instruction set becomes complex. The computer designers intend to reduce this gap and include large instruction set, more addressing mode and various HLL statements implemented in hardware. The development of powerful high level programming languages give rise to another problem known as the semantic gap, the difference between the operations provided in HLLs and those provided in computer architecture. Even more powerful and complex high level programming languages has been developed by the researcher and industry people. One of the most visual forms of evolution associated with computers is that of programming languages. Multiple Processor: This category covers a number of different organizations and objectives.Examples are instruction pipelining and vector processing. Pipelining: A means of introducing parallelism into the essentially sequential nature of a machine instruction program.The insertion of this element into the memory hierarchy dramatically improves performance. Cache Memory: First introduced commercially on IBM S/360 Model 85 in 1968.Microprogramming eases the task of designing and implementing the control unit and provide support for the family concept. Microprogrammed Control Unit: Suggested by Wilkes in 1951, and introduced by IBM on the S/360 line in 1964.A set of computers are offered, with different price/performance characteristics, that present the same architecture to the user. The family concept decouples the architecture of a machine from its implementation.
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