module M6809D (dev)
title '6809 memory decode
Jean Designer    Data I/O Corp Redmond WA   24 Feb 1987'

" The device type may be specified on the command line with
" ABEL4 m6809d -arg P16L8

@ifnb (?dev) { m6809d device '?dev';   @message 'Using "?dev".'};

@ifb  (?dev) { m6809d device 'P14L4';  @message 'Using "P14L4".'};

	A15,A14,A13,A12,A11,A10	pin 1,2,3,4,5,6;
	ROM1,IO,ROM2,DRAM	pin 14,15,16,17;

	H,L,X	= 1,0,.X.;
	Address	= [A15,A14,A13,A12, A11,A10,X,X, X,X,X,X, X,X,X,X];

equations
	!DRAM	= (Address <= ^hDFFF);

	!IO	= (Address >= ^hE000) & (Address <= ^hE7FF);

	!ROM2   = (Address >= ^hF000) & (Address <= ^hF7FF);

	!ROM1	= (Address >= ^hF800);

test_vectors (Address -> [ROM1,ROM2,IO,DRAM])
	      ^h0000  -> [  H,  H,  H,   L ];
	      ^h4000  -> [  H,  H,  H,   L ];
	      ^h8000  -> [  H,  H,  H,   L ];
	      ^hC000  -> [  H,  H,  H,   L ];
	      ^hE000  -> [  H,  H,  L,   H ];
	      ^hE800  -> [  H,  H,  H,   H ];
	      ^hF000  -> [  H,  L,  H,   H ];
	      ^hF800  -> [  L,  H,  H,   H ];
end