from the photos I can see the printerport adaptor uses the MOSCHIP MCS98005V-BA
Attachment 433804
on the photo of the C22 board I can not read the IC numbers but expect they are octal buffers like the 74ACT245
Attachment 433806
I would expect to see 2 LEDs flicker while rotating rotary dial
and 2 LEDs to be on to indicate the possition of the switches
another LED to be a power ON indicator
John