3 Multiple instruction stream single data stream MISD

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Computer Science Organization | Mapping Techniques

In this article, we will learn about the mapping techniques of the cachememory in Computer Science Organization. Submitted by Shivangi Jain, on July 17, 2018

Mapping techniques

The process of transfer the data from main memory to cache memory is called asmapping. In the cache memory, there are three kinds of mapping techniques areused. 1. Associative mapping 2. Direct mapping 3. Set Associative mappingComponents present in each line are: 1. Valid bit: This gives the status of the data block. If 0 then the data block is not referenced and if 1 then the data block is referenced. 2. Tag: This is the main memory address part. 3. Data: This is the data block.

Computer Science Organization | Addressing Modes

In this article, we will learn about basic concept of Addressing modes incomputer system organization. Classification of addressing modes is alsoprescribed in this article. Submitted by Abhishek Kataria, on July 08, 2018

Addressing Modes

The term ‘addressing mode’ refers to the mechanism which will use to specifythe operands. An operand can be specified as the part of the instruction, orthe reference of the memory location which had given. An operand could also bean address of CPU register. Addressing modes can also be defined by thefollowing criteria which are as follows: * Addressing modes shows the way where exactly the required object is present. * In this condition, object may be an instruction or data. * The output of the addressing mode is Effective Address [EA], where EA is the actual address where exactly the object is present in the computer. * There is a different convention which is used to indicate the various addressing modes some of them follow here: 1. /I ——- Immediate addressing mode. 2. Reg.Name ——-Register addressing mode. 3. [ ] ————Direct addressing mode. 4. @/ ( ) ———-Indirect addressing mode. 5. Index Reg Name ——Indexed addressing mode. 6. +/- ————– Auto indexed addressing mode.

1) Instruction cycle

This concept describes the execution sequence of the program. Instructioncycle includes the first two phases, fetching and decoding.

Computer Science Organization | Virtual Memory

In this article, we will learn concept of virtual memory in computer systemwith a block diagram. Explanation on virtual memory address translation andadvantages of virtual memory is also prescribed in this article. Submitted by Abhishek Kataria, on July 18, 2018

Virtual Memory

The physical memory which we are using in our computer system is in megabytesnot in gigabytes. If we try to run a program which is not completely fit intomain memory, then, in this case, we try the parts of currently being executedare stored in main memory and remaining portion is stored in a secondarydevice such as hard disk.If this case occurs, so it’s necessary that all parts of a program which areneeded for execution are first brought into the main memory. When a newsegment of a program is brought and memory is full, it must replace anothersegment already in the memory. So the techniques which are used to moveprogram and data block into the main memory when they required for executionare called virtual memory techniques.

Virtual Memory Organization

* Programmers discern a larger memory which is allocated on the disk this memory is referred to as virtual memory. A programmer enjoys a huge virtual space to develop his or her program or software. * Program or a processor references a data space which is independent of available physical memory space. The address issued by a processor is called a virtual address. * The virtual address can be translated into the physical address by a combination of hardware and software components. * If a virtual address is a part of the program in the physical memory then it can be accessed immediately and if the address is not in the main memory then its content will be brought into the main memory before it can be used. * To improve the performance hardware are added to the system, these hardware units are known as Memory Management Unit (MMU). * In the paging system, page table helps us to find the physical address form virtual address since the virtual address space is used to develop a process. So the work of the MMU is to translate the virtual address to physical address.

Paging and Virtual Memory Address Translation

The mechanism for reading a data from memory involves translation of virtualaddress to physical address. In this basically, the concept of paging is usedfor doing the translation. Following steps are there for address translationswhich are given below: 1. Virtual address space of the program is divided into fixed length units called, pages. 2. Each page will contain a block of words that will occupy the locations in the main memory. After this, each page will be mapped into the fixed location in the main memory called page frame. 3. The address generated by the processors to fetch the word memory can be divided into the two parts: 4. In this case, high order bits are interpreted as virtual page number and these bits are used to fetch corresponding page frame number from the page table. 5. Low order bits of the address gives the offset and it specifies as the particular byte within in a page. 6. By adding this virtual page number to the contents of the content page table, the address of the corresponding entry in the page table is obtained. 7. Each entry in a page includes a control bit that describes a validity of a page, the status of the page, and whether the page has been modified.

Advantages of virtual memory

1. A process which is larger than the main memory, it will be executed because of the demand paging. 2. By the concept of a virtual memory, many processes can be maintained in the main memory. 3. It will allow greater programming level by using only less space for a particular process.TOP Interview Coding Problems/ChallengesComputer Science Organization | PipeliningHome » Computer Science Organization

2) Single instruction stream – multiple data stream (SIMD)

SIMD has multiple processing units and one control unit. They correspond toarray processors. In SIMD, all the processing elements received the sameinstruction from the control unit but operate on different data sets fromdistinct data streams.

3) Multiple instruction stream single data stream (MISD)

In MISD, there are n processor units each receiving distinct instructionoperating over the same data stream and its derivatives. This means oneprocessor becomes the input of the next processor.

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