COMPUTER ARCHITECTURE

1. COMPUTER ARCHITECTURE By: Maria Ramila I. Jimenez XUCC

2. A CLASSIFICATION OF COMPUTER ARCHITECTURES Outline 1.2.1 Von Neumann Machines 1.2.2 Non-von Neumann Machines 1.3 Measuring the Quality of a Computer Architecture 1.4 Factors Influencing the Success of a Computer Architecture

3. Flynn’s classification of the 3 types of computers in existence Flynn(1966) classified computer architectures by a variety of characteristics: number of processors number of programs they can execute memory structure

4. Flynn’s classification of the 3 types of computers in existence Categories Single instruction stream, single data stream (SISD)

5. Flynn’s classification of the 3 types of computers in existence Single instruction stream, single data stream (SISD) SISD computers have one CPU that executes one instruction at a time (hence a single instruction stream) and fetches or store one item of data at a time( hence a single data stream). The von Neumann architectures belong to this classification.The von Neumann architectures belong to this classification.

6. Flynn’s classification of the 3 types of computers in existence Single instruction stream, multiple data stream (SIMD) SIMD machines have a CU that operates like a von Neumann machine(i.e., it executes a single instruction stream), but SIMD machine have more than one PE. The CU generates the control signals for all of the PEs, which execute the same operation, generally in lockstep, on different data items (hence multiple data streams). Processor arrays fall into this category.Processor arrays fall into this category.

7. Flynn’s classification of the 3 types of computers in existence Categories Single instruction stream, multiple data stream (SIMD) Processor arrays fall into this category. Processor arrays fall into this category.

8. Flynn’s classification of the 3 types of computers in existence Multiple instruction stream, multiple data stream (MIMD) These machines have more than one independent processor, and each processor can execute a different program (hence multiple instruction streams) on its own data (hence multiple data streams). MIMD are also called multiprocessors. (multiprocessor system)MIMD are also called multiprocessors. (multiprocessor system)

9. Flynn’s classification of the 3 types of computers in existence Multiple instruction stream, multiple data stream (MIMD) MIMD are also called multiprocessors. (multiprocessor system)MIMD are also called multiprocessors. (multiprocessor system)

10. (MISD) Multiple instruction stream, single data stream (MISD) Logically, machines in this class would execute several different programs on the same data item. There are currently no machines of this type, although some MIMD systems may be used in this manner. These 4th category of architecture does not exist at present.These 4th category of architecture does not exist at present.

11. Multiprocessor Architectures Multiprocessor architectures can be divided into 2 categories based on the organization of their memory system: Global memory (GM) system architectures. One global memory system is shared by all of the processors. Local-memory (LM) system architectures. One storage system exists for each processor. Multiprocessors with LM may also have GM and are also called multiple processors. Current high-performance computer architectures are of this type and all 3 architectures discussed are shown with global memory.Current high-performance computer architectures are of this type and all 3 architectures discussed are shown with global memory.

12. SIMD and MIMD SIMD and MIMD machines are parallel processors because they operate in parallel on more than one datum at a time. SIMD computers have the ff. characteristics: They distribute processing over a large amount of hardware. They operate concurrently on many diff. data elements. They perform the same computation on all data elements.

13. SIMD and MIMD SIMD machines differ in the way their PEs access memory. The PEs of GM-SIMD computers share the same storage system, while those of LM-SIMD computers have independent storage systems. Processor arrays are SIMD architectures. They have 1 CU and many PEs. The CU generates control signals for all the PEs, w/c perform exactly the same computation simultaneously but w/ diff. data.

14. An LM-SIMD processor array Consisting of 16 PEs, and a single CU. The PEs shown are with its own local memory, organized in a 4x4 array; hence the name processor array.Consisting of 16 PEs, and a single CU. The PEs shown are with its own local memory, organized in a 4x4 array; hence the name processor array.

15. SIMD and MIMD The term CU in the SIMD context Usually the CU is itself a von Neumann computer with its own register set, ALU, and CU of the type to be described in chapter2. This computer is referred to as a CU bec. it was designed solely to control the PEs in a processor array, rather than to operate as a stand-alone computer.

16. SIMD and MIMD Historically, SIMD architectures include several components in addition to the CU and PEs. They usually include a host computer for loading programs, for configuring the array of PEs, and for supervising I/O. The host is usually a conventional computer w/ a well-established OS. The architects may also provide specialized I/O devices for

17. SIMD and MIMD reformatting the arrays of data, for example, or for performing high-speed I/O. MIMD computers have the ff. characteristics: They distribute processing over a number of independent processors. They share resources, including main memory, among component processors. Each processor operates independently and concurrently. Each processor runs its own program.

18. SIMD and MIMD Different MIMD architectures have diff. interconnection networks, diff. processors, diff. memory-addressing structures, and diff. synchronization and control structures. Multiple-processor computers can be categorized as being either: - tightly coupled - loosely coupled Interconnection networks allow the component processors to communicate w/ each other.Interconnection networks allow the component processors to communicate w/ each other.

19. SIMD and MIMD depending on how the processors access each other’s memory. The processors in a tightly coupled multiprocessor generally share one memory system. Those of a loosely coupled multiprocessor may also share a memory system, but each processor also has its own local memory and generally executes programs out of it.

20. Tightly coupled multiple-processor Architecture of a tightly coupled multiple processor computer M-memory systems; P-processorsM-memory systems; P-processors

21. Loosely coupled multiple-processor computer Architecture of a loosely coupled multiple-processor computer. M-memory systems; P-processors M-memory systems; P-processors

22. SIMD and MIMD Thus tightly coupled and loosely coupled computers correspond approximately to the GM-MIMD and LM-MIMD classifications, respectively. Examples of GM-MIMD: dual processor of the CDC 6600 series and Cray XM-P Examples of the LM-MIMD: Carnegie-Mellon Cm and the Tandem/16.

23. Architectural categories Combining the various classifications discussed so far and RISCs yields the 6 architectural categories listed in the table.Combining the various classifications discussed so far and RISCs yields the 6 architectural categories listed in the table.

24. Other architectures In von Neumann machines programs determine the flow of control. In dataflow architectures, the availability of data determines when the machines will perform operations The computational models that dataflow processors implement, called dataflow models, are inherently parallel, and architects have designed dataflow machines to implement these models efficiently. Computer designers and architects have introduced a number of alternatives to the architectures just described such as dataflow architectures and neural networks.Computer designers and architects have introduced a number of alternatives to the architectures just described such as dataflow architectures and neural networks.

25. Other architectures A dataflow machine, like an MIMD computer has many independent PEs, but these do not execute programs. When the supervising processor finds available data, it routes the data and an instruction to a PE, w/c performs the operation and forwards the result to memory. Bec. There is no program in the conventional sense, dataflow architectures are neither SIMD nor MIMD.

26. Other architectures Neural networks are loosely based on biological systems. Like dataflow processors, they do not execute conventional programs and therefore do not fall into the SIMD or MIMD classifications. Current applications include signal processing pattern recognition A number of manufacturers are developing special-purpose devices to implement them. At the present time the technology is in its infancy.A number of manufacturers are developing special-purpose devices to implement them. At the present time the technology is in its infancy.

27. Other architectures Special-purpose machines Because of the specialized functions they perform. Generally, they use conventional architectures that have been optimized for specific applications. They differ from conventional architectures because they are required to solve a particular equation or to handle specific applications, such as very large arrays very large databases highly parallel algorithms

28. Other architectures Included in this group are: artificial intelligence machines high-level-language machines image-processing machines three-dimensional display processors computers for embedded control AI is the branch of CS that endows computers w/ humanlike intelligence; architects design AI machines to efficiently execute AI programming languages like LISP.AI is the branch of CS that endows computers w/ humanlike intelligence; architects design AI machines to efficiently execute AI programming languages like LISP.

29. Other architectures Image-processing involves extracting info. from images or enhancing the quality of an image. three-dimensional display processors generally provide special-purpose hardware for displaying graphical images and find applications in CAD, CAM, and animation computers for embedded control In embedded control the processors are included as integral parts of a machine of some type; for ex., many printers have embedded processors to control the printing process.In embedded control the processors are included as integral parts of a machine of some type; for ex., many printers have embedded processors to control the printing process.