cntbuf.abl

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module CNTBUF   
title 'Counter and Bidirectional Buffer
Dennis Freidman   Data I/O Corp   22 May 1990'

        cntbuf  device 'E0320';
" Works in E0310, E0320, P16R4, P16RP4, P16V8R, P18U8 and others

        Clk,Clr,Dir,OE          pin 1,2,3,11;
        Q3,Q2,Q1,Q0             pin 14,15,16,17;
        A1,A0,B1,B0             pin 12,13,18,19;
        
        Ck,X,Z  = .C. , .X., .Z.;

        A    = [A1,A0];
        B    = [B1,B0];
        Count = [Q3,Q2,Q1,Q0];

equations

        Count.OE = !OE;
        Count.C  = Clk;

        Count := (Count.fb + 1) & !Clr;

trace ([Clk,OE,Clr,Dir] -> [Count,A,B])
test_vectors 'Counter'
       ([Clk,OE,Clr] -> Count)
        [ Ck, 0, 1 ] ->    0;
        [ Ck, 0, 0 ] ->    1;
        [ Ck, 0, 0 ] ->    2;
        [ Ck, 0, 0 ] ->    3;
        [ Ck, 1, 0 ] ->    Z;
        [ Ck, 0, 0 ] ->    5;
        [ Ck, 0, 0 ] ->    6;
        [ Ck, 0, 0 ] ->    7;
        [ Ck, 0, 0 ] ->    8;
        [ Ck, 0, 0 ] ->    9;
        [ Ck, 0, 0 ] ->   10;
        [ Ck, 0, 0 ] ->   11;
        [ Ck, 0, 0 ] ->   12;
        [ Ck, 0, 0 ] ->   13;
        [ Ck, 0, 0 ] ->   14;
        [ Ck, 0, 0 ] ->   15;
        [ Ck, 0, 0 ] ->    0;
        [ Ck, 0, 0 ] ->    1;
        [ Ck, 0, 0 ] ->    2;
        [ Ck, 0, 0 ] ->    3;
        [ Ck, 0, 1 ] ->    0;
        [ Ck, 0, 1 ] ->    0;

equations
        A = B;  A.OE =  Dir;
        B = A;  B.OE = !Dir;

trace([Clk,OE,Clr,Dir]-> [Count,A,B]);
test_vectors 'Buffer'
       ([ A , B ,Dir] -> [ A , B ])
        [ X , X , 0 ] -> [ Z , X ];
        [ X , X , 1 ] -> [ X , Z ];
        [^h0, X , 0 ] -> [ X ,^h0];
        [^h1, X , 0 ] -> [ X ,^h1];
        [^h2, X , 0 ] -> [ X ,^h2];
        [^h3, X , 0 ] -> [ X ,^h3];
        [ X ,^h0, 1 ] -> [^h0, X ];
        [ X ,^h1, 1 ] -> [^h1, X ];
        [ X ,^h2, 1 ] -> [^h2, X ];
        [ X ,^h3, 1 ] -> [^h3, X ];
end