I had a similar issue with BSD 2.11.
So, I hope this helps.
You can use vt100. However, make sure your baud rate is 9600.
stty 9600
(SIMH makes the virtual adjustment so you don’t need to worry
about SIMH settings.)
I am using BSD 2.11 on a Mac with SIMH. I noticed the
console port would have a short window. But, logging into dz
ports were fine. Setting the console baud rate to match the
dz11 settings fixed the issue.
So, I suspect either a setting in vi that changes the window
size on slow devices or it’s hard coded somewhere. I will take
a look.