William Stallings Computer Organization and Architecture

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William Stallings Computer Organization and
Architecture

• Memory

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Terminologi

• Memory cell
• Memory Word
• Byte
• Address
• Volatile Memory
• Write and Read Operation

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Memori Cell Operation
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Diagram Memori
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Characteristics

• Location
• Capacity
• Unit of transfer
• Access method
• Performance
• Physical type
• Physical characteristics

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Location

• CPU
• Internal
• External

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Capacity

• Internal memory
• a byte
• a word in 8, 16, 32 bit
• External memory
• a byte

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Unit of Transfer

• Internal
• in a word or larger, such as 16, 128, 256
• External
• Usually a block which is much larger than a word

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Access Methods (1)?

• Sequential
• Memory is organized into unit of data record.
• Access must be made in a specific linear sequence
• Store addressing information is used to separate
  record and assist in the retrieval process.
• Access time depends on location of data
• e.g. tape

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Access Methods (2)?

• Direct
• Memory is organized into blocks
• Individual blocks have unique address
• Access is by jumping to vicinity plus sequential
  search
• Access time depends on location
• e.g. disk

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Access methode (3)?

• Random
• Individual addresses identify locations exactly
• Access time is independent of location
• e.g. RAM
• Associative (4)
• Data is located by a comparison with contents of
  a portion of the store
• A word is retrieved based on a portion of its
  content rather than its address
• Access time is independent of location
• e.g. cache

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Performance

• Access time
• Time between presenting the address and getting
  the valid data
• Memory Cycle time
• Time may be required for the memory to recover
  before next access
• Cycle time is access recovery
• Transfer Rate
• Rate at which data can be moved

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Physical Types

• Semiconductor
• RAM
• ROM
• Magnetic
• Disk Tape
• Optical
• CD DVD
• Others
• Bubble
• Hologram

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Physical Characteristics

• Volatility
• Erasable
• Power consumption

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The Bottom Line

• How much?
• Capacity
• How fast?
• Time is money
• How expensive?

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So you want fast?

• 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

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Memory Hierarchy

• Registers
• In CPU
• Internal or Main memory
• RAM
• External memory
• Backing store

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Hierarchy List

• Registers
• L1 Cache
• L2 Cache
• Main memory
• Disk
• Optical
• Tape

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Memory Hierarchy - Diagram