A counter argument which will be well understood as self-justifying if made
by a boot rom specialist:
Every machine I make winds up looking a bit different. The new bus has
different logic. The chip initialisation differs. Blobs become more
interestingly hard to handle because associated pre boot initialisation
dependency keeps rising and no amount of push back from me stops it.
If I make my boot ROM forth, I can reduce my marginal costs to writing
forth code for most variant handling and occasional uplift of new
primitives and constants into the forth for edge cases. My life gets
simpler if I implement the wheel of life.
I would imagine after the 10th sub variant, one would wind up thinking like
this.
Of course a rational alternative is to maintain a monrepo of all the
variants and recompile all of them all the time to make all the boot ROMs
far smaller. But making the generic anything ROM and changing only some
forth would be attractive.
Never owned this problem. I did work with two groups doing lsi-11 images
for x.25 handling on yorkbox, and they definitely thought more like you
than me on this: hand code it, code it well, they aren't general purpose
devices when doing this kind of job. (I annoyed them a lot which tends to
"probably they were right" in hindsight on my part)
G