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Status: Tags: Links: Nand2Tetris Unit 6

Assembler Logic

Process

• Read the next Assembly language command
• Break it into different fields (Parsing)
• Lookup binary code for each field
• Combine codes into a single machine language command
• Output machine language command Does the following process until the end of the file is reached

Treatment of Code Parts

• Whitespace
  • Ignore
• Instructions
  • Converts into binary
• Symbols
  1. Pre-defined
     • Only a instructions
     • Replace symbol with value
  2. Labels (label)
     • label will turn into the memory location value of the next instruction
     • @label turns into @value
  3. Variables @var
     • If @var is not used in parentheses, it becomes a variable
     • Given a unique memory address starting at 16, and refer to it for further occasions of the naem

Symbols

Types

• Pre-defined symbols
• Labels
  • Runs through the code initially to map all addresses
  • ex) JMP loop
• Variables
  • ex) Load R1, weight

Process

• Stored in a Symbol Table

References: