41 lines
1.2 KiB
Markdown
41 lines
1.2 KiB
Markdown
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## Machine Code
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- Machine language instructions
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- Directly control CPU
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- Strictly numerical
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- Lowest-level representation of a compiled or assembled program
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- Lowest-level visible to programmer
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- Internally microcode might used
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- Hardware dependent
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- Higher-level languages translated to machine code
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- Compilers, assemblers and linkers
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- Not for interpreted code
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- Interpreter runs machine code
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- Assembly is effectively human readable machine code
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- Has mnemonics for opcodes etc
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## Microcode
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- Layer between CPU hardware and instruction set architecture
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- Normally written during design phase
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- Deployed to ROM or PLA
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- Programmable logic array
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- Machine code often has some backward compatibility
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- Microcode is circuit specific
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## Byte Code
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Portable Code
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- Efficient execution by interpreter
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- Compact numeric codes, constants and references
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- Encode compiler output following analysis and validation
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- Can be further compiled
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- JIT
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- Typically passed to VM
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- Java, Python
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## Object Code
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- Product of compiler
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- Sequence of statements
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- Machine code
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- Intermediate
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- RTL
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- Linked to form executable
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- Object code portion of machine code not yet linked
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