Since many owners of models that don't have a printer port pointed out: There are some unpopulated parts on their main PCB and asked if the printer port could be retro-fitted.
Well, I guess so!
So there are only 8+1 bits in the OUT direction and a single bit in the IN direction. The latter is used to tell if a printer is connected and ready.
As I have found out, it is also used for PC communication: Using the 8 data output bits, the notebook selects, which bit of the incoming byte it wants to be set on Pin 11. So I guess the PC-Link cable contains an 8-bit "AND" IC.
But enough chatter: Here is the list of missing parts for the printer port:
|<IC>||P9506AN / DM74LS244N||74LS244N Octal Buffer|
|<Connector>||Ribbon cable to D-SUB 25||Ribbon 1-9 to Pin 1-9|
Ribbon 10 to Pin 11
Ribbon 11 to Pins 18...25 and Shield
(where Ribbon 1 is near C93)
|C12||403||40 nF capacitor|
|C93||222 AEC||2.2 nF capacitor|
|R35, R41, R42, R43, R44||brown black orange||10k resistors|
|Q10||LM90 / 14C / M[otorola] 521||NPN transistor|
|Q11||LM90 / 15 C / M[otorola] 512||PNP transistor|
Please let me know if you find any mistakes. Also, drop me a line if you managed to pull off the upgrade procedure. I'd love to hear about it!