Not sure how, but I managed to balls up the installation initially. Didn’t install a boot partition. Rather than take a risk that something else was missing too, I went ahead and reinstalled. For whatever reason it seems to have gone fine this time; I seem to think I didn’t do the configuration after selecting packages last time, but some of the screens for it were familiar.
Whatever, it’s working fine now. Slackware lesson one: because it’s not fancy, you can treat it like any other basic set of packages that’re there to get the hardware working. A big complaint with Ubuntu that I have is that it’s hard to work out how to fix shit if it doesn’t automatically install just fine first time. With slackware, I was able to go back to my “wait a second, what does a shell do if I try that out?” approach and see what the issue was. Ubuntu’s shells always have fucked up fonts for me.