> "BI" fonts can, it seems, largely be traced to the impact
> of PostScript

There was no room for BI on the C/A/T. It appeared in
troff upon the taming of the Linotron 202, just after v7
and five years before PostScript.

> Seventh Edition Unix shipped a tc(1) command to help
> you preview your troff output with that device before you
> spent precious departmental money sending it to the
>  actual typesetter.

Slight exaggeration. It wasn't money, It was time and messing
with film cartridges, chemicals, and wet prints. You could buy a
lot of typesetter film and developer for the price of a 4014.

Doug