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Memory (Part 2)
Dokumen tersebut membahas tentang memori komputer khususnya cache memory. Cache memory merupakan memori cepat yang berfungsi menyimpan data dan instruksi yang sering diakses untuk mempercepat akses prosesor. Dokumen menjelaskan definisi, cara kerja, desain, dan jenis-jenis cache memory seperti direct mapping, associative mapping, serta perbandingan antara cache dengan memori utama.
Memory (Part 2)
- 1. Organisasi dan Arsitektur Komputer AjengSavitri Puspaningrum, M.Kom Pertemuan 26
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- 3. Learning theDefinition of Cache Learning How Cache’s Works Learning Characteristic of Cache
- 4. So you wantfast? It is possible to build a computer which uses only static RAM (see later) This would be very fast This would need no cache How can you cache cache? This would cost a very large amount
- 5. Cache Small amountof fast memory Sits between normal main memory and CPU May be located on CPU chip or module
- 6. Cache Memory Mekanismepenyimpanan data sekunder berkecepatan tinggi yang digunakan untuk menyimpan data / instruksi yang sering diakses. Memberi kecepatan memori yang mendekati memori yang paling cepat yang bisa diperoleh, dan pada waktu yang sama menyediakan kapasitas memori yang besar dengan harga yang lebih murah dari jenis-jenis memori semikonduktor.
- 7. Cache and MainMemory
- 8. Cara Kerja Komputermembutuhkan data Mencarinya pada Cache. Jika data ditemukan, prosesor akan langsung membacanya dengan delay yang sangat kecil. Tetapi jika data yang dicari tidak ditemukan,prosesor akan mencarinya pada RAM yang kecepatannya lebih rendah. Kapasitas memori cache yang semakin besar juga akan meningkatkan kecepatan kerja komputer secara keseluruhan.
- 9. Cache Read Operation- Flowchart
- 10. Cache Design Addressing Size Mapping Function Replacement Algorithm Write Policy Block Size Number of Caches
- 11. Cache Addressing Wheredoes cache sit? Between processor and virtual memory management unit Between MMU and main memory Logical cache (virtual cache) stores data using virtual addresses Processor accesses cache directly, not thorough physical cache Cache access faster, before MMU address translation Virtual addresses use same address space for different applications Must flush cache on each context switch Physical cache stores data using main memory physical addresses
- 12. Size does matter Cost More cache is expensive Speed More cache is faster (up to a point) Checking cache for data takes time
- 13. Direct Mapping Eachblock of main memory maps to only one cache line i.e. if a block is in cache, it must be in one specific place Address is in two parts Least Significant w bits identify unique word Most Significant s bits specify one memory block The MSBs are split into a cache line field r and a tag of s-r (most significant)
- 14. Direct Mapping Summary Address length = (s + w) bits Number of addressable units = 2s+w words or bytes Block size = line size = 2w words or bytes Number of blocks in main memory = 2s+ w/2w = 2s Number of lines in cache = m = 2r Size of tag = (s – r) bits
- 15. Direct Mapping Pros& Cons Simple Inexpensive Fixed location for given block If a program accesses 2 blocks that map to the same line repeatedly, cache misses are very high
- 16. Victim Cache Lowermiss penalty Remember what was discarded Already fetched Use again with little penalty Fully associative 4 to 16 cache lines Between direct mapped L1 cache and next memory level
- 17. Associative Mapping Amain memory block can load into any line of cache Memory address is interpreted as tag and word Tag uniquely identifies block of memory Every line’s tag is examined for a match Cache searching gets expensive
- 18. Associative Mapping Amain memory block can load into any line of cache Memory address is interpreted as tag and word Tag uniquely identifies block of memory Every line’s tag is examined for a match Cache searching gets expensive
- 19. Direct and SetAssociative Cache Performance Differences Significant up to at least 64kB for 2-way Difference between 2-way and 4-way at 4kB much less than 4kB to 8kB Cache complexity increases with associativity Not justified against increasing cache to 8kB or 16kB Above 32kB gives no improvement (simulation results)
- 20. Memori Internal danExternal Memori internal adalah memori yang dapat diakses langsung oleh prosesor register yang terdapat di dalam prosesor, cache memori dan memori utama berada di luar prosesor. Memori eksternal adalah memori yang diakses prosesor melalui piranti I/O disket dan hardisk.
- 21. Operasi Sel Memori Elemen dasar memori Sel memori memiliki sifat – sifat tertentu
- 22. Sifat Sel Memori Sel memori memiliki dua keadaan stabil (atau semi-stabil), yang dapat digunakan untuk merepresentasikan bilangan biner 1 atau 0. Sel memori mempunyai kemampuan untuk ditulisi (sedikitnya satu kali). Sel memori mempunyai kemampuan untuk dibaca.
- 23. Terminal Fungsi SelMemori
- 24. Main Memory Memoriutama merupakan media penyimpanan dalam bentuk array yang disusun word atau byte, kapasitas daya simpannya bisa jutaan susunan. Setiap word atau byte mempunyai alamat tersendiri. Data yang disimpan pada memori utama ini bersifat volatile. Memori utama digunakan sebagai media penyimpanan data yang berkaitan dengan CPU atau perangkat I/O.
- 25. Tipe Main Memory RandomAccess Memory ( RAM ) Read Only Memory ( ROM ) CMOS Memory Virtual Memory Main Memory
- 26. Semiconductor Memory Types MemoryType Category Erasure Write Mechanism Volatility Random-access memory (RAM) Read-write memory Electrically, byte-level Electrically Volatile Read-only memory (ROM) Read-only memory Not possible Masks Nonvolatile Programmable ROM (PROM) Electrically Erasable PROM (EPROM) Read-mostly memory UV light, chip-level Electrically Erasable PROM (EEPROM) Electrically, byte-level Flash memory Electrically, block-level
- 27. Refference Stalling, William, ComputerOrganization and Architecture, 10th Edition, Pearson, 2015 Abdurohman, Maman, Organisasi dan Arsitektur Komputer revisi ke-4, Penerbit Informatika, 2017
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