As of August 2017 I have a functioning calculator! Here's a video of it in action:

• Clear all => "+.00000 00000"

• Clear display => "+xxxxx xxxxx"

• Key "12" => "+12xxx xxxxx"

• ln => 2.48490664 

• Key "12" => "+12xxx xxxxx"

• X^2 => "+144.00 00000" (you can see it "thinking")

• X^2 => "+20736. 00000"

• X^2 => "+42998 1696.0"

• Clear all => "+.00000 00000"

• Key "45" => "+45xxx xxxxx"

• square root => "+6.7082 03933"

• Key "45" => "+45xxx xxxxx"

• Enter => "+.00000 00000" - it calculates the log of 45

• Key "12" => "+12xxx xxxxx"

• X= => "+540.00 00000" - you can see it thinking here too.