You can add 8k Ram to NB Emulator very easy.
First make sure you don’t have selected the expansion interface module or CP/M.
Start the emulator.
Select ‘Save memory map’ from the tools menu.
Edit the created file (Newbrain.ini).
You should see that at bank 4 there is no chip (4=-1) change that to 4=103.
Save & close.
Restart the emulator.
Type PRINT FREE and you should have 38K free.