Though I think I had checked the partition table, recently I set it bootable after a reinstall (maybe I had forgotten to, after not making an install with a new partition table for a very long time). After that, it may have halted during boot once, or that was before I set it bootable... but finally, my most recent boot with 14.1 was successful, when I only had a blank DVD in the drive rather than a Slackware one.
I was not able to write to the DVD yet even as root, but that is something else I can maybe talk about elsewhere, if I need to. I suspect the hardware is designed for Windows, because I had much other trouble with it, like not getting the touchscreen to work, and the touchpad stopping working after I loaded gpm after 'telinit 1' to upgrade, which may have been a mistake, but the hardware just seems difficult... I am pretty sure it had halted booting from hard drive in 14.0, and it cannot boot from 14.1's UEFI boot, so I had to make a DVD not booting with that, and then finally also do an upgrade from hard drive, since the disc seemed to have had problems being written (not enough to not boot, which was good because USB booting also always halted)... again I can discuss some of this elsewhere if it becomes relevant, unless anyone wants to say anything else.