One of the apps that I used to create more or less 50 songs with is PhoenixStudio for Windows Mobile 2003. Before I learned to change the drum samples in the app for the drum kit, I used the standard kit, which was mostly 909-samples. At least that's what the developer emailed me, when I asked him, but he couldn't remember exactly. The main reason to buy a TR-09 is because the sounds became so familiar to me.
And because I wanted to hook it up to the TB-303.