I'm old retired Northwest DC9 captain and the best rendition I found is by Stellan Hemberely (sp?) a SAS captain. He's has 2 free downloads for the series 40 and series 20 aircraft. Believe me the systems and switches all work the way they're suppose to. I don't have his web page address but you can probably Google his name and find it. The spelling of his last name might be incorrect but it's close. Don't waste your money on Iron Knuckles the systems and switches authenticity is awful.

            Tom