Jtag looks simple?

found these:

• https://balau82.wordpress.com/2014/08/10/jtagduino-jtag-connection-using-arduino/
• http://www.khjk.org/log/2013/aug/jtagbang.html

and got openocd.sourceforge.net/ to program http://www.stm32circle.com/resources/stm32primer.php it has a RLINK adapter built in.
but I feel I'm missing something.

this was some help www.robofun.ro/docs/Manual_PROGRAMMER.pdf.
but not sure why elf files will program but not bin.
thought elf was re-locatable to do with OS?

and what about these Bootloaders.