Changes
E1 = data
[http://groups.google.com/group/comp.sys.amstrad.8bit/browse_thread/thread/ce201414eff39a29/19cb6f7056d49480?lnk=gst&q=nc100+sound#19cb6f7056d49480 | Russell Marks's notes about sound generation on NC100]
[[NC100 IO Specification]]