You can use Quite Universal Circuit Simulatar (QUCS) to create analog simulation, digital simulation and optimization. The components that are reserved such as:

Lumped components: Resistor, Resistor US; Capacitor, Inductor, Ground, Subcircuit Port, Transformer, symmetric Transformer, dc Block, dc Fee, Bias T, attenuator, Amplifier, Isolator, Circutor, Gyrator, Pahse Shifter, Coupler, Current Probe, Voltage Probe, Mutual Inductors, 3 Mutual Inductors, Switch, Relay, Equation Defined RF Device, Equation Defined 2-port RF Device. Sources: dc Voltage Source, dc Current Source, ac Voltage Source, ac Current Source, Power Source, Noise Voltage Source, Noise Current Source, Voltage Controlled Current Source, Current Controlled Current Source, Voltage Controlled Voltage Source, current controlled voltage source, Voltage Pulse, Current Pulse, Rectangle Voltage, Rectangle Current, Correlated Noise Sources, Correlated Noise Sources, Correlated Noise Sources, AM modulated Source, PM modulated Sources, Exponential Current Pulse, Exponential Voltage Pulse, File Based Voltage Source, File Based Current SOurce. Probes: Current Probe, Voltage Probe.Transmission Lines: Transmission Line, 4-Terminal Transmission Line, Twisted-Pair, Coaxial Line, Rectangular Waveguide, RLCG Transmission Line, Substrate, Microstrip Line, Coupled Microstrip Line, Microstrip Corner, Microstrip Mitered Bend, Microstrip Step, Microstrip Tee, Microstrip Cross, Microstrip Open, Microstrip Gap, Microstrip Via, Microstrip Radial Stub, Coplanar Line, Coplanar Open, Coplanar Short, Coplanar Gap, Coplanar, Bond Wire. Nonlinear components: Diode, npn transistor, pnp transisitor, npn transistor, pnp transisitor, n-JFET, p-JFET, n-MOSFET, p-MOSFET, depletion MOSFET, n-MOSFET, p-MOSFET, depletion MOSFET, OpAmp, Equation Define Device, Diac, Triac, Thyristor. Verilog-a devices: HICUM L2 v2.1, FBH HBT, Modular OpAmp, HICUM L2 v.2.22, Logarithmic Amplifier, npn HICUM L0 v1.12, pnp HICUM L0 v1.12, Potentiometer, MESFET, EPFL-EKV NMOS 2.6, EPFL-EKV PMOS 2.6, npn HICUM L0 v1.2, pnp HICUM L0 v1.2, HICUM L2 v2.23,Photodiode, Phototransistor.Digital Components: digital source, Inverter, n-port OR, n-port NOR, n-port AND, n-port NAND, n-port XOR, n-PORT XNOR, Buffer 4×2 AndOr, 4×3 AndOr, 4×4 AndOr, 2to1 Mux, 4to1 Mux, 8to1 Mux, 2to4 Demux, 3to8 Demux 4to16 Demux, 1Bit HalfAdder, 1Bit FullAdder, RS-FlipFlop, D-FlipFlop, D-FlipFlop w/SR, JK-FlipFlop, JK-FlipFlop w/ SR, T-FlipFlow w/ SR, Gated D-Latch, Logic 0, Logic 1, 2Bit Pattern, 3Bit Pattern, 4Bit Pattern, A2D Level Shifter, D2A Level Shifter, 4Bit Bin2Grey, 4Bit Grey2Bin, 1Bit Comparator, 2Bit Comparator, 4Bit Comparator, 4Bit HPRI-Bin, VHDL file, Verilog file, digital simulation. File components: SPICE netlist, 1-port S parameter file, 2-port S parameter file, n-port S parameter file, Subcircuit. Simulations: dc simulation, Transient simulation, ac simulation, S-parameter simulation, Harmonic balance, Parameter sweep, digital simulation, optimization. Diagrams: Cartesian, Polar, Tabular, Smith Chart, Admittance Smith, Polar-Smith Combi, Smith-Polar Combi, 3D-Cartesian, Locus Curve, Timing Diagram, Truth Table. Paintings: Line, Arrow, Text, Ellipse, Rectangle, filled Ellipse, filled Rectangle, Elliptic Arc.

You can download Quite Universal Circuit Simulatar (QUCS) from: http://sourceforge.net/projects/qucs/files/qucs-binary/0.0.15/qucs-0.0.15-setup.exe/download