Comment by baruz

>maybe Xerox before that?

Yes, the cut/copy/paste system and its shortcuts were developed at the Xerox PARC LRG as part of Smalltalk-76. They used a Control key.

>and adopted by DOS

DOS inherited it from CP/M by way of the 86-DOS clone that Gates purchased. Kildall used the TOPS-10 while developing PL/M and CP/M and adopted some of its conventions, including control-break.