Allan Herriman <ua.moc.matc@namirreh.nalla>
	2005-04-07: wrong return address pushed in stack during interrupts.

Ed Blanchard <moc.hcetixv@bde>
	2005-11-29: output sX, (sY) not working as expected.

John Providenza <moc.oborp@pnhoj>
	2007-04-12: found bug in the return stack code.