It's really great. I also did a TX81Z song 12 years ago.

https://soundcloud.com/electrosock/beer-for-breakfast

Bought the TX81Z really cheap back in the day via eBay. I loved the OS of the machine, the most wonderful thing about it is that with only 5 buttons and a 2 line LED display you could tweak any detail about the sound, including changing the FM algorithm