The current status of getting FreeDOS booting (for ReadSpeed and SpinRite) is a bit of a mess. We're in a transition period, where as of 2021 Intel (as the leader of the UEFI consortium) has decreed that legacy BIOS and legacy booting must no longer be possible on new machines. There have been machines over the last couple of years who have been produced without the ability to legacy boot. (Mac's in particular, and recent Dell's.)
Because it's a bit of a mess with no way to know without a lot of work, we're going to try and maintain this thread as a place where people can report machines they definitely know are too modern to be able to boot legacy DOS. This will most certainly mean they have a UEFI and not a BIOS. To be most helpful to other users, you will need to provide identifiers they would be searching for, so motherboard model number or PC model number if it is from an OEM (Dell, Lenovo, HP, Asus, etc.) Please don't post machines you suspect don't work here until you after you've made an honest attempt to try to get it to work (disabled secure boot, enabled the CSM, enabled legacy booting, etc.)
Because it's a bit of a mess with no way to know without a lot of work, we're going to try and maintain this thread as a place where people can report machines they definitely know are too modern to be able to boot legacy DOS. This will most certainly mean they have a UEFI and not a BIOS. To be most helpful to other users, you will need to provide identifiers they would be searching for, so motherboard model number or PC model number if it is from an OEM (Dell, Lenovo, HP, Asus, etc.) Please don't post machines you suspect don't work here until you after you've made an honest attempt to try to get it to work (disabled secure boot, enabled the CSM, enabled legacy booting, etc.)