The assembler program is a way to parse a description of that
semi-abstract instruction set and turn it into instructions to be
input to the linker.
If you want to see what the instructions look like in assembly for a given architecture, say amd64, there
are many examples in the sources of the standard library, in packages such as
<a href="/pkg/runtime/"><code>runtime</code></a> and
<a href="/pkg/math/big/"><code>math/big</code></a>.