/**************************************************************************
** ND120 CPU, MM&M                                                       **
** CPU/CS/WCS                                                            **
** Writable Control Store                                                **
** SHEET 21 and 22 of 50                                                 **
**                                                                       **
** This module has 16 RAM CHIPS of type 16K (4Kx4) Static RAM for LUA    **
** (4KByte Microcode)                                                    **
**                                                                       **
** This module has 16 RAM CHIPS of type 16K (4Kx4) Static RAM for UUA    **
** (4KByte for Writable Control Store?)                                  **
**                                                                       **
** Last reviewed: 9-NOV-2024                                             **
** Ronny Hansen                                                          **
***************************************************************************/

module CPU_CS_WCS_21_22 (
    input sysclk,    // System clock in FPGA
    input sys_rst_n, // System reset in FPGA

    input  [63:0] CSBITS_63_0,  //! 64 bits CSBITS (output when IDB IN writes a 16 bit part to the CSBITS) (from CPU_CS_TCV_20.CSBITS_OUT)
    output [63:0] CSBITS_63_0_OUT,  //! Control Store Bits - 64-bit output containing the control store data/instructions (to CPU_CS_16.CSBITS)

    input [11:0] LUA_11_0,  //! Load Upper Address - 13-bit output for upper address bits of control store (same net as CPU_CS_16.LUA_12_0[11:0])
    input        ELOW_n,    //! Enable LOW chips
    input        WW0_n,
    input        WW1_n,
    input        WW2_n,
    input        WW3_n,


    input [11:0] UUA_11_0,
    input        EUPP_n,    //! Enable UPPER chips
    input        WU0_n,
    input        WU1_n,
    input        WU2_n,
    input        WU3_n
);


// REFACTOR possibility: SWITCH to ONE big DRAM logic

  /*******************************************************************************
   ** The wires are defined here                                                 **
   *******************************************************************************/
  wire [63:0] s_lua_csbits_in;
  wire [63:0] s_lua_csbits_out;
  wire [11:0] s_lua_address;
  wire        s_elow_n;

  wire        s_ww3_n;
  wire        s_ww2_n;
  wire        s_ww1_n;
  wire        s_ww0_n;

  wire [63:0] s_uua_csbits_in;
  wire [63:0] s_uua_csbits_out;
  wire [11:0] s_uua_address;
  wire        s_eupp_n;
  wire        s_wu3_n;
  wire        s_wu2_n;
  wire        s_wu1_n;
  wire        s_wu0_n;



  /*******************************************************************************
   ** Here all input connections are defined                                     **
   *******************************************************************************/

  // LUA
  assign s_lua_csbits_in[63:0] = CSBITS_63_0;
  assign s_lua_address[11:0] = LUA_11_0;

  assign s_elow_n = ELOW_n;  // Enable LUA RAM chips
  assign s_ww0_n = WW0_n;  // Enable write for LUA bits 15-0
  assign s_ww1_n = WW1_n;  // Enable write for LUA bits 31-16
  assign s_ww2_n = WW2_n;  // Enable write for LUA bits 47-32
  assign s_ww3_n = WW3_n;  // Enable write for LUA bits 63-48


  // UUA
  assign s_uua_csbits_in[63:0] = CSBITS_63_0;
  assign s_uua_address[11:0] = UUA_11_0;

  assign s_eupp_n = EUPP_n;  // Enable UUA RAM chips
  assign s_wu0_n = WU0_n;  // Enable write for UUA bits 15-0
  assign s_wu1_n = WU1_n;  // Enable write for UUA bits 31-16
  assign s_wu2_n = WU2_n;  // Enable write for UUA bits 47-32
  assign s_wu3_n = WU3_n;  // Enable write for UUA bits 63-48




  /*******************************************************************************
   ** Here all output connections are defined                                    **
   *******************************************************************************/
  // ELOW_n = 0 means ENABLE LUA RAM CHIPS
  // EUPP_n = 0 means ENABLE UUA RAM CHIPS

  // mux data out?
  //assign CSBITS_63_0_OUT = (!s_elow_n) ?  s_lua_csbits_out[63:0] : (!s_eupp_n) ? s_uua_csbits_out[63:0] : 64'b0;
  // or data out
  assign CSBITS_63_0_OUT       = s_lua_csbits_out[63:0] | s_uua_csbits_out[63:0];

  /*******************************************************************************
   ** Here all sub-circuits are defined                                          **
   *******************************************************************************/

  // Announce the WCS mode at sim start so there is no ambiguity about whether
  // the WCS was pre-loaded (SKIP_WCS_LOAD) or filled by the runtime load phase.
  initial begin
`ifdef SKIP_WCS_LOAD
    $display("[ND120] WCS mode: PRELOADED (SKIP_WCS_LOAD) - runtime microcode load phase bypassed");
`else
    $display("[ND120] WCS mode: RUNTIME LOAD (normal PROM->WCS copy)");
`endif
  end

  // Lower address: 0x0000-0x0FFF

  IDT6168A_20 #(.INIT_FILE("wcs_16C.hex")) CHIP_16C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[63:60]),
      .D_3_0_OUT(s_lua_csbits_out[63:60]),
      .WE_n(s_ww3_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_17C.hex")) CHIP_17C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[59:56]),
      .D_3_0_OUT(s_lua_csbits_out[59:56]),
      .WE_n(s_ww3_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_18C.hex")) CHIP_18C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[55:52]),
      .D_3_0_OUT(s_lua_csbits_out[55:52]),
      .WE_n(s_ww3_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_19C.hex")) CHIP_19C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[51:48]),
      .D_3_0_OUT(s_lua_csbits_out[51:48]),
      .WE_n(s_ww3_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_20C.hex")) CHIP_20C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[47:44]),
      .D_3_0_OUT(s_lua_csbits_out[47:44]),
      .WE_n(s_ww2_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_21C.hex")) CHIP_21C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[43:40]),
      .D_3_0_OUT(s_lua_csbits_out[43:40]),
      .WE_n(s_ww2_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_22C.hex")) CHIP_22C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[39:36]),
      .D_3_0_OUT(s_lua_csbits_out[39:36]),
      .WE_n(s_ww2_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_23C.hex")) CHIP_23C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[35:32]),
      .D_3_0_OUT(s_lua_csbits_out[35:32]),
      .WE_n(s_ww2_n)
  );


  IDT6168A_20 #(.INIT_FILE("wcs_24C.hex")) CHIP_24C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[31:28]),
      .D_3_0_OUT(s_lua_csbits_out[31:28]),
      .WE_n(s_ww1_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_25C.hex")) CHIP_25C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[27:24]),
      .D_3_0_OUT(s_lua_csbits_out[27:24]),
      .WE_n(s_ww1_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_26C.hex")) CHIP_26C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[23:20]),
      .D_3_0_OUT(s_lua_csbits_out[23:20]),
      .WE_n(s_ww1_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_27C.hex")) CHIP_27C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[19:16]),
      .D_3_0_OUT(s_lua_csbits_out[19:16]),
      .WE_n(s_ww1_n)
  );


  IDT6168A_20 #(.INIT_FILE("wcs_28C.hex")) CHIP_28C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[15:12]),
      .D_3_0_OUT(s_lua_csbits_out[15:12]),
      .WE_n(s_ww0_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_29C.hex")) CHIP_29C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[11:8]),
      .D_3_0_OUT(s_lua_csbits_out[11:8]),
      .WE_n(s_ww0_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_30C.hex")) CHIP_30C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[7:4]),
      .D_3_0_OUT(s_lua_csbits_out[7:4]),
      .WE_n(s_ww0_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_31C.hex")) CHIP_31C (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_lua_address[11:0]),
      .CE_n(s_elow_n),
      .D_3_0_IN(s_lua_csbits_in[3:0]),
      .D_3_0_OUT(s_lua_csbits_out[3:0]),
      .WE_n(s_ww0_n)
  );


  // Upper address: 0x1000-0x1FFF

  IDT6168A_20 #(.INIT_FILE("wcs_16D.hex")) CHIP_16D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[63:60]),
      .D_3_0_OUT(s_uua_csbits_out[63:60]),
      .WE_n(s_wu3_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_17D.hex")) CHIP_17D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[59:56]),
      .D_3_0_OUT(s_uua_csbits_out[59:56]),
      .WE_n(s_wu3_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_18D.hex")) CHIP_18D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[55:52]),
      .D_3_0_OUT(s_uua_csbits_out[55:52]),
      .WE_n(s_wu3_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_19D.hex")) CHIP_19D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[51:48]),
      .D_3_0_OUT(s_uua_csbits_out[51:48]),
      .WE_n(s_wu3_n)
  );



  IDT6168A_20 #(.INIT_FILE("wcs_20D.hex")) CHIP_20D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[47:44]),
      .D_3_0_OUT(s_uua_csbits_out[47:44]),
      .WE_n(s_wu2_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_21D.hex")) CHIP_21D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[43:40]),
      .D_3_0_OUT(s_uua_csbits_out[43:40]),
      .WE_n(s_wu2_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_22D.hex")) CHIP_22D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[39:36]),
      .D_3_0_OUT(s_uua_csbits_out[39:36]),
      .WE_n(s_wu2_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_23D.hex")) CHIP_23D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[35:32]),
      .D_3_0_OUT(s_uua_csbits_out[35:32]),
      .WE_n(s_wu2_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_24D.hex")) CHIP_24D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[31:28]),
      .D_3_0_OUT(s_uua_csbits_out[31:28]),
      .WE_n(s_wu1_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_25D.hex")) CHIP_25D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[27:24]),
      .D_3_0_OUT(s_uua_csbits_out[27:24]),
      .WE_n(s_wu1_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_26D.hex")) CHIP_26D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[23:20]),
      .D_3_0_OUT(s_uua_csbits_out[23:20]),
      .WE_n(s_wu1_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_27D.hex")) CHIP_27D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[19:16]),
      .D_3_0_OUT(s_uua_csbits_out[19:16]),
      .WE_n(s_wu1_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_28D.hex")) CHIP_28D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[15:12]),
      .D_3_0_OUT(s_uua_csbits_out[15:12]),
      .WE_n(s_wu0_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_29D.hex")) CHIP_29D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[11:8]),
      .D_3_0_OUT(s_uua_csbits_out[11:8]),
      .WE_n(s_wu0_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_30D.hex")) CHIP_30D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[7:4]),
      .D_3_0_OUT(s_uua_csbits_out[7:4]),
      .WE_n(s_wu0_n)
  );

  IDT6168A_20 #(.INIT_FILE("wcs_31D.hex")) CHIP_31D (
      .clk(sysclk),
      .reset_n(sys_rst_n),
      .A_11_0(s_uua_address[11:0]),
      .CE_n(s_eupp_n),
      .D_3_0_IN(s_uua_csbits_in[3:0]),
      .D_3_0_OUT(s_uua_csbits_out[3:0]),
      .WE_n(s_wu0_n)
  );

endmodule