<p><pre><code>   Hopper both invented the concept of compiler and 
   wrote the 1st one. 
</code></pre>
No.<p>A_0 was a simple linker in 2016 parlance, <i>not</i> a compiler.<p>In Hopper&#x27;s own description: &quot;All I had to do was to write down a set of call numbers, let the computer find them on the tape, bring them over and do the additions. This was the first compiler&quot; (cited from [1]). Here &quot;find them on the tape&quot; refers to 
her habit of collecting 
subroutines  over the years and put them on tape. Each routine was given a call number, so that it the machine could find it on the tape.<p>I&#x27;m happy to believe that she created the first linker, although I have never looked into the history of linking and linkers.<p><pre><code>   Plankalkül was [...] before general purpose programmable 
   computers (ENIAC) were built so irrelevant.
</code></pre>
The first general purpose computer was Zuse&#x27;s Z3, at least in some understanding of this concept [2].<p>[1] C. Marx, Grace Hopper: The First Woman to Program the First Computer in the United States.<p>[2] R. Rojas, How to Make Zuse&#x27;s Z3 a Universal Computer.