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--- spo600:machine_language [2025/01/08 21:40] – [Relationship to Other Languages] chris
+++ spo600:machine_language [2025/01/08 21:44] (current) – chris
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 Many early computers encoded the [[Operation|operation]] and [[Addressing Mode|addressing mode]] as a distinct [[word#byte|byte]] or [[Word|word]] called an [[OpCode|opcode]], followed by zero or more additional bytes for the arguments, where the number of additional bytes is implied by the opcode.
+Obviously, instructions are specific to a particular type of CPU, and the same opcode may mean very different things on different processors. For example, the opcode 0xA9 ($A9) means "Load Accumulator - Immediate" (LDA #) on a 6502, but the same opcode means "Test" (compare bits) on an x86 system.
 Other processors encode instructions as bit fields packed with a instruction word. For example, specific bits within an instruction word specify the operation, other bits specify the addressing mode, and still other bits specify the register(s) and other arguments.