PKG_BAL, Allocate whole bank

rst $08, defw $240f


IN:	A=reason code;
		bnk_any, don't care which bank is allocated
		bnk_even, even-numbered bank required (to bind to seg 0)

OUT(success):
	Fc=0
	A=bank number allocated
OUT(failure):
	Fc=1
	A=rc_room, no free banks available
	A=rc_unk, unknown reason code

Registers changed after return:
  ..BCDEHL/IXIY same
  AF....../.... different

Notes:
