Hi, looking for some help to figure out where to start with a problem.

My sort of XT compatible Zenith Z171 works well with MSDOS 3.3. However when I try to use MSDOS 5 the keyboard stops working.

1. Cntl alt del still works
2. Keystrokes otherwise dont register as input.
3. Eventually after a bunch of keystrokes, the computer beeps on every keystroke. I think I that means the keyboard buffer is full.

So it seems like msdos5 is not pulling keystrokes from the keyboard buffer. Seems strange when msdos3.3 works fine.

Msdos 6.22 has the same problem.

I'll start researching but does anyone have any thoughts on this one?