I recently purchased a VT220 and all the hardware necessary to hook it to my macbook pro. After several hours of fiddling I got it working with a shell - my only problem is my shell of choice, ZSH, behaves weirdly. Backspace and Arrow keys, as well as Ctrl-a and Ctrl-e do not actually move the cursor and while they do delete it is kind of awkward.
Using BASH on the other hand, the device works flawlessly. Is there an issue with some control character or something that ZSH is using?