The main text surely was typed on a typewriter. Computer printed letters didn't really start happening until 1980 or so. Around then I bought a Diablo 630 daisywheel printer. That would produce beautiful typed pages, but monospaced. The printer paper had sprocket holes which were torn off after printing, but if you ran your finger over the edges you could tell.
Proportional computer fonts weren't printed much until laser printers appeared, which revolutionized everything.
I doubt anyone had a laser printer at home until Apple's LaserWriter first sold in 1985 (for $6995!), but laser printing was first developed between 1968 and 1972 at Xerox Parc, with IBM selling the first commercial laser printers in 1976.[1]
Proportional computer fonts weren't printed much until laser printers appeared, which revolutionized everything.