Logisym is a digital logic simulator, intended to assist you in understanding, debugging, and verifying, the operations of combinational and sequential digital logic circuits. The simulator utilizes a 'unit delay' model, and very accurately represents the operations of circuits built from the basic logic functions providing a timing diagram of the trace output, much like a 16 trace ocilloscope. The device library internal to logisym includes the following functions: AND, OR, NAND, NOR, (up to 8 input); XOR NOT, BUFFER, an RS flipflop (cross coupled NAND), a positive edge triggered D type flipflop, and a positive edge triggered JK flipflop. Up to 650 logic devices may be defined, and 16 points may be observed during a simulation. Logisym provides 26 different signals or 'clocks' to be used as inputs to the circuit(s) being simulated. These are: A variable frequency eight bit up/down counter, a variable frequency four bit ring counter, a variable rate random data generator, and eight bits of data controlled by way of the function keys on the keyboard. Fixed high and low logic levels are also available as tiepoints for unused inputs
