So I had a few email reports about Calamares crashes in legacy BIOS mode. Legacy BIOS support has been discontinued with TTOS Linux "Chicago" and this has been stated previously. We just haven't prioritized blocking the ability to boot into legacy BIOS mode from the installer ISO because the ISO can still be used to troubleshoot older legacy BIOS installs. Since the emails keep coming, future updates will soon remove the feature to boot to legacy BIOS. The modern generations of hardware that this ISO is intended to run on are all new enough to support EFI/UEFI mode. A small BIOS edit to place it into EFI/UEFI boot mode is all that is needed to successfully boot and install TTOS Linux. In the meantime, please enjoy the current ISO's as the pending changes will have no difference in the OS except disabling the ability to boot into legacy mode for the installer.
Have an awesome day, and thank you for your continued support!