The cable ends look like this:
On my 15" monitor, they show up approximately actual size. They're male on one side and female on the other, so you can stack them. The 82169A can go to lots of HPIB devices at once this way. The connectors look like Centronics parallel but there are only 24 contacts.
For SELECT, the address of the plotter (or whatever device on the HPIB you're talking to) will be in decimal in the X register. The 82169A has to be the last device in the loop; so let's say you have an HPIL printer, a tape or disc drive, and an 82164A or FSI-164 RS-232 interface converter ahead of it. That puts the 82169A at address 4. Then the HPIB devices must be given addresses in the range of 5 to 31. You typically do that with DIP switches. They don't have to be consecutive like the HPIL devices automatically are. You might for example have a signal generator at address 9, a DMM at address 15, a programmable power supply at address 7, and a relay unit at address 17. Let's say the plotter is at address 12, set with DIP switches on the plotter as 01100. To talk to the plotter, you do 12 SELECT.