This problem with pins on an 84 gave me same trouble some time ago !

However the soulition followed.
1 x HC138
4 x HC244
4 x HC374
1 x LM016

30 outputs 30 inputs RS line and a beeper in a latch and two buttons. Started
life as a box to test the integerty of multicore cables but now does lots
more with the addition of relays ect. If anybody is instrested in my boring
but useful hardware I will try and convert Orcad file to GIF or somthing and
send it.

Cheers Steve.....