This is piece of software is not very faultless, but works. Here is my very simply test of Basic-G interpreter:
Inverted characters 
and 
was made by pressing and holding CTRL and SHIFT keys, then clicking to character key. At end of line must be pressed the RETURN (ENTER) key to store line into RAM. The command RUN starts this little program. Inverted "L" character represents cursor in LETTER mode.
What is program doing? CTRL/R sets the GII mode, ginit initializes screen for paint and CTRL/S sets the GI mode back. CTRL/Z switches cursor to second screen (the Ready message will not be print into visible screen). Oh yes, SORD has more than one screen (exactly 9 screens) and two neighbouring screens are accessible/switchable by CTRL/V, CTRL/Z and CTRL/Y commands. Other GI screens are accessible by the ESCRN [<screen number 0..8>][,<switch 0..2>] command. After program ends, the cursor is hidden on the opposite screen and may be shown by CTRL/Z command (CTRL/Y command switches to opposite screen).
This is piece of software seems be OK (game cartridges work), but...
...return from GII mode to GI mode fails. I test MESS version 0.56. Under version 0.61.1 and 0.61.2 SORD emulation not works ever.