DBB Digital Breadboard is a full GUI digital logic circuit simulator. 
    Digital Breadboard currently supports 2 and 3 input AND, OR, NAND,
    and NOR gates, NOT and XOR gates, D, JK, and SR edge-triggered 
    flip-flops, multiple independant clocks, switched and pulsed inputs,
    outputs, Vcc, GND, independant 4-channel oscilloscope, event counters,
    variable speed timer, preferences printing, and more.  Requires
    AmigaDOS 2.x  Version 1.1.  Freeware, binary only.  Author: Dan Griffin