So, if you have an 8-bit computer and it can perform a fetch cycle, meaning it can access its memory, how do you create words the computer understands.

If LDA "load the accumulator" is in the instruction set and its just something we named for humans and the computer understands binary...

How was this idea communicated in binary.

I see it's another language, in logic, two-state system,

literal b/c logic gates areenter image description here

But how do you say load and add and such

These are the human terms but what would the computer hear?

  • 1
    $\begingroup$ Look up opcodes and instruction set. $\endgroup$ Jan 31, 2019 at 2:53
  • $\begingroup$ You can also look up ISA. $\endgroup$ Jan 31, 2019 at 4:22
  • $\begingroup$ I'm not sure if this is about principles of computer architecture (ontopic) or building CPUs (offtopic). Community votes, please: offtopic? $\endgroup$
    – Raphael
    Jan 31, 2019 at 7:25
  • $\begingroup$ You picked an image of a quantum computer. Totally different thing. $\endgroup$
    – gnasher729
    Jan 31, 2019 at 7:52

1 Answer 1


LDA gets translated by the assembler to bytes that the machine can interpret.

The contents of these bytes are set by the instruction decoder, and often made to make the decoder as simple as possible. For example some bits may get passed straight to the execution unit so add and subtract differ by a single bit which triggers inverting the second operand and sets the carry in bit. The bits that decide which registers to use would be common to all instructions, stuff like that

The 3 letter acronyms are just shorthands set by whoever was in charge of writing the assembler.


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