E.1 busmon.abl

module busmon
title 'PC Bus Monitor   S. Harrington   Spring 94'
busmon device 'P22V10';

"Inputs
    Clk     pin 1;
    IOR     pin 2;
    IOW     pin 3;
    MEMR        pin 4;
    MEMW        pin 5;
    AEN     pin 6;
    A9,A8,A7,A6 pin 7,8,9,10;
    A5,A4,A1,A0 pin 11,13,14,15;
    ALE     pin 16;

"Outputs
    CP      pin 23; "rising edge increments counters
    DEN0        pin 22; "active low enable for 244s
    DEN1        pin 21;
    DEN2        pin 20;
    CE      pin 19; "active low Count Enable
    Load        pin 18; "active low Counter Preset
    Q1      pin 17;

Select = A9 & A8 & !A7 & !A6 & !A5 & !A4 & !AEN;
" Ports 300-30F

Equations "!=NOT &=AND #=Or $=XOR !$=XNOR
    CE = !(!AEN & (!MEMR # !MEMW));
    DEN0 = !(Select & !IOR & !A1 & !A0);
    DEN1 = !(Select & !IOR & !A1 & A0);
    DEN2 = !(Select & !IOR & A1 & !A0);
    Load = !(Select & !IOW);
    Q1 := 1;
    Q1.ar = ALE;
    Q1.clk = !Clk;
    CP.clk = !Clk;
    CP := Q1;

end busmon