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Erstellt / Aktualisiert 21.06.2019 / 21.06.2019
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0 Exakte Antworten 11 Text Antworten 0 Multiple Choice Antworten
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What are registers?

Registers are the "variables" on the CPU

Immnediate acces for the CPU

Cannot write Memory -> Memory

  • Aways: Memory -> Register -> Memory
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What can be held in registers?

Register can hold:

  • Data (numbers)
  • Addresses (also numbers, but with a different meaning)
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What can registers be used for?

Registers can be used to:

  • Perform computations
  • Read / Write memory
  • Execute instructions
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Name some registers in a 32 bit system and their function.

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  • EAX -> Adding stuff
  • EBX -> Referencing stuff
  • ECX -> Counting stuff
  • EDX -> Data stuff
  • ESI -> Points to a source
  • EDI -> Points to a destination
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Name the 3 registars that contain instruction pointer, stack pointer and base Pointer. (32 bit)

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  • EIP -> Instruction Pointer -> Next instruction to be executed
  • ESP -> Stack Pointer -> Top of Stack
  • EBP -> Base Pointer -> Current Stack Frame (Bottom)
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How does a CPU interpret instructions?

A CPU looks at bytes, and then decides what to execute based on them.

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What is the difference between big and little endian?

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Big endian: The most significant byte of the data is placed at the byte with the lowest address.

Little endian: The least significant byte of the data is placed at the byte with the lowest address.

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What are the 2 most important rings in the ring modle and what are their characteristics?

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Ring 0: Kernel (Kernelspace)

  • Can be intercated with by using "syscalls"

Ring 3: Userspace

  • Where all programs run

How to transit from userspace to kernelspace?

  • System Calls (syscall)