There is an small error in the code that ...

There is an error in the code that however does not prevent the correct execution of the simulator. You can fix by yourself if you want to.

err: char ps = (WORD)&vid; // video memory pointer
err: char ls = (WORD)&vbtmp; // line buffer pointer

fix: char ps = (char)&vid; // video memory pointer
fix: char ls = (char)&vbtmp; // line buffer pointer