Are such sewing machine available? Ones that start or stop or do reinforcement stitches by computer instruction?
There are a number of computer controlled sewing machines on the market. Brother is one company, Husqvarna, and a number of other manufacturers produce devices which use software running from a computer, which typically creates a file sent to the machine. The file contains instructions to be executed with respect to movement of the mechanism which shifts the fabric (encased in an embroidery hoop) and movement of the needle and thread.
The above references consumer grade devices, possibly described as hobbyist level, although custom embroidery and sewing shops will use them for commercial use.
If you require industrial grade device related information, consider to clarify your question. I'd expect that industrial grade devices would be even more fully computer controlled.
I have a client who manufacturers quilt producing machines. Many dozens of needles with corresponding thread spools, precise fabric movement, multiple fabric layers (of course, it's a quilt) and take-up systems for the completed product. At the time I was able to view the systems, they were operating on an embedded Windows XP OS, which also contained the software to generate the stitching and related operations.