Writing under the cursor in x86 assembly using video mapped memory

Question

I am writing a simple application that tries to use video mapped memory (Starting at address 0B800). For the most part I can write directly to that memory and the characters appear instantly on screen, but I find if I try to write directly under the cursor what ever I tried to write does not stick. Is there a way around this? How can I write directly under the cursor?

Currently using something like this to write to the memory:

mov word ptr ES:[DI], BX

where BX has the attributes and the character I want to write.

Answer 1

I looked up what interrupts dosbox supports and int 33h was on the list. Calling int 33h with ax = 2 hides the mouse, then after that the mov word ptr ES:[DI], BX worked just fine, finally I called int 33h again with ax = 1 to make the mouse visible once again.