NAME   rev ADDR type chip Description
---------------------------------------------------------------------------
SPRHSTOP H 1D2  W    A    UHRES sprite vertical display stop

    BIT#  15  14  13  12  11  10  09  08     07  06  05  04  03  02  01  00
SPRHWRM   x   x   x   x   x  v10  v9  v8     v7  v6  v5  v4  v3  v2  v1  v0

	SPRHWRM = Swaps the polarity of ARW* when the SPRHDAT comes
	out so that external devices can detect the RGA and put
	things into memory.(ECS and later chips only)