module Z74X163 
title ’4-bit Binary Counter’ 
Z74X163 device ’P16V8R’;

" Input pins 
CLK, !OE                        pin 1, 11; 
A, B, C, D                      pin 2, 3, 4, 5; 
!LD, !CLR, ENP, ENT             pin 6, 7, 8, 9;

" Output pins 
QA, QB, QC, QD, RCO             pin 19, 18, 17, 16, 15;

" Set definitions 
INPUT = [D, C, B, A]; 
COUNT = [QD, QC, QB, QA];

equations

COUNT := !CLR & ( LD & INPUT
                # !LD & (ENT & ENP) & (COUNT + 1)
                # !LD & !(ENT & ENP) & COUNT);

RCO = (COUNT == [1,1,1,1]) & ENT;

end Z74X163