Removed 6821 porta_r/portb_r/ca1_r/ca2_r/cb1_r/cb2_r functions as they only returned what you'd written to the chip, only a couple of those were ever used (by audio/exidy.c). Removed some ca*/cb* read callbacks that just returned what had already been pushed or always returned 0. As there are no longer any cb2 read callbacks that functionality has been removed. [smf]