Memory Address Mapping and Decode

------- ----- ------------------------- Start End Resource ------- ----- ------------------------- 0000 03FF EPROM (1 K bytes) 0400 3FFF Unused images of EPROM 4000 7FFF RAM (16 K bytes) 8000 BFFF Unused C000 C007 Registers (8) in the UART C008 FFFF Unused images of the UART ------- ----- -------------------------

The following RTL describes the required glue logic for the memory map:

  module address_decode(abus, rom_cs, ram_cs, uart_cs);
     input [15:14] abus;
     output rom_cs, ram_cs, uart_cs;
     assign rom_cs = (abus == 2'b00);  // 0x0000
     assign ram_cs = (abus == 2'b01);  // 0x4000
     assign uart_cs = !(abus == 2'b11);// 0xC000
  endmodule