The PC printer port has an eight bit output port at &H378 
and four bits of input at &H379.
It is these that we use to comminicate with the ADC. 
The output port is labelled D0-7.
The input bits are BUSY(Bit 7),ACK(6),PE(5) and SLCT(4).
It is essential to note that BUSY is inverted were as the rest are not.

D0-7    Pins 2-9
BUSY    Pin 11 (Inverted)
ACK     Pin 10
PE      Pin 12
SLCT    Pin 13
 

NB 2 input and 2 output bits are not used by the ADC and therefore could be used for other things.

MFL'94