de0-zx-spectrum/spectrum.v

module spectrum(
	input CLOCK_50,
	output wire[7:0] LED
);

reg[13:0]  address;
wire[7:0]  mem_data;
	
rom0 rom(
	.address(address),
	.clock(CLOCK_50),
	.q(mem_data)
);


reg [15:0] A;                  // Global address bus
wire [7:0] D;                   // CPU data bus
wire [7:0] ram_data;            // Internal 16K RAM data
wire RamWE;
// assign RamWE = A[15:14]==2'b01 && nIORQ==1 && nRD==1 && nWR==0;
assign RamWE = 0;
wire[12:0] vram_address;
wire[7:0] vram_data;

ram16 ram0(
	.clock(CLOCK_50),
	
	.address_a({12'b0, A[2:0]}),
	.data_a(D),
	.q_a(ram_data),
	.wren_a(0),
	
//	.address_b({1'b0, vram_address}),
	.address_b(A[13:0]),
	.data_b(8'b0),
	.q_b(vram_data),
	.wren_b(0)
);

reg[21:0] counter;
always @(posedge CLOCK_50) 
begin
	counter <= counter + 1;
	if (counter == 0)
	begin
		address <= address + 1;
		A <= A + 1;
	end
end
assign LED[3:0] = ram_data[3:0];
assign LED[7:4] = mem_data[7:4];

endmodule