mirror of
https://github.com/sxpert/hp-saturn
synced 2024-11-16 19:50:19 +01:00
67 lines
1.1 KiB
Verilog
67 lines
1.1 KiB
Verilog
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`include "bus_commands.v"
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`ifndef _HP48_ROM
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`define _HP48_ROM
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/**************************************************************************************************
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*
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* Rom module
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* accesses the calculators firmware
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*
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*
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*/
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module hp48_rom (
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input strobe,
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input [19:0] address,
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input [3:0] command,
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output reg [3:0] nibble_out
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);
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localparam ROM_FILENAME = "rom-gx-r.hex";
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//
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// This is only for debug, the rom should be stored elsewhere
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//
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`ifdef SIM
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reg [3:0] rom [0:(2**20)-1];
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`else
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//reg[3:0] rom [0:(2**16)-1];
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reg[3:0] rom [0:(2**12)-1];
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`endif
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reg [3:0] i_cmd;
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reg [19:0] pc_ptr;
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reg [19:0] data_ptr;
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initial
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begin
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$readmemh( ROM_FILENAME, rom);
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end
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/**************************************
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*
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*
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*
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*/
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always @(posedge strobe) begin
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case (command)
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`BUSCMD_LOAD_PC: begin
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pc_ptr <= address;
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i_cmd <= `BUSCMD_PC_READ;
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// $display("ROM - LOAD_PC %5h", address);
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end
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`BUSCMD_PC_READ: begin
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nibble_out <= rom[pc_ptr];
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pc_ptr <= pc_ptr + 1;
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i_cmd <= command;
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// $display("ROM PC_READ %5h -> %h", pc_ptr, rom[pc_ptr]);
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end
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endcase
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end
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endmodule
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`endif
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