Everyone serious about gamedev at his age would be well versed in assembly language and such. It's unthinkable nowadays but normal for graphics programmers in 80s and early-mid 90s.
You can do it too if you follow his steps. I mean by programming Apple ][ and then IBM PC in assembly.
The dude was definitely doing stuff no one else had ever done.
Then again I have a 90's game dev book that covers ASM as well as manufacturing then programming your own sound card using the parallel port so... you're not wrong.
You can do it too if you follow his steps. I mean by programming Apple ][ and then IBM PC in assembly.