HammerHead is a classic free drum machine software similar to the TR-909.
The HammerHead beat maker features six separate channels, 29 built-in drum sounds, six complete breakbeats.
You can also import up to six samples of your own.
Your patterns can be saved to CD-quality wave files to use them with your sequencer, sampler, or tracker software.
This HammerHead download will run under Vista and Windows 7, however you may have to run it as Administrator to get it to work.
Here is a basic overview:
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