You can use trackers like Madtracker, Renoise. All you need is basic waveform samples like Square, Sine, Saw, Pulse and Triangle. Using the Arpeggio effect you can get those retro chord sounds.
Another option is using Reason. The SubTractor synth has all of those basic waveforms. You can add extra '8-bit feeling' by using the Scream distortion on top of that with the 'digital' preset. (play around a bit with the resolution and rate)
hope this helps!