The finger BassLine (App Store link) is a musical instrument for the iPhone and the iPod Touch that’s heavily inspired by the legendary Roland TB-303.

It turns your iPhone/iPod touch into a monophonic synthesizer with built-in pattern-based step sequencer, and it’s priced at a bite-sized $3.99.

Bassline doesn’t accurately duplicate a 303’s look or sound – but it does turn your iPhone into a bassline synth that can turn out some interesting acid sounds.

Synth section features include:

• Oscillator with two waveforms (sawtooth or square)
• Stable low-pass filter allowing high resonance values not leading to self oscillation 
• Graphical representation of the filter parameters

Sequencer section features include:

• Individual pattern lengths (up to 64 sixteenths)
• Emphasized notes and pauses
• Smooth transition between notes
• Functions to clear, transpose, shift, and clone patterns

Live performance features:

• Realtime modulation of the filter parameters using the intuitive pad-controls
• Pattern switches take effect on downbeat