You're right, thanks for your correction. My main point was a location of the Control key. I guess with IBM XT keyboard CTRL-[ become a most reasonable option h

You're right, thanks for your correction. My main point was a location of the Control key. I guess with IBM XT keyboard CTRL-[ become a most reasonable option https://en.wikipedia.org/wiki/IBM_PC_keyboard#/media/File:IBM_Model_F_XT.png https://en.wikipedia.org/wiki/IBM_PC_keyboard#/media/File:IB...