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[/] [zx_ula/] [branches/] [xilinx/] [spectrum_48k_for_digilent_spartan3_starter_kit_with_ps2_keyboard/] [tv80n.v] - Rev 27
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// // TV80 8-Bit Microprocessor Core // Based on the VHDL T80 core by Daniel Wallner (jesus@opencores.org) // // Copyright (c) 2004 Guy Hutchison (ghutchis@opencores.org) // // Permission is hereby granted, free of charge, to any person obtaining a // copy of this software and associated documentation files (the "Software"), // to deal in the Software without restriction, including without limitation // the rights to use, copy, modify, merge, publish, distribute, sublicense, // and/or sell copies of the Software, and to permit persons to whom the // Software is furnished to do so, subject to the following conditions: // // The above copyright notice and this permission notice shall be included // in all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. // IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY // CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, // TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE // SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. // Negative-edge based wrapper allows memory wait_n signal to work // correctly without resorting to asynchronous logic. module tv80n (/*AUTOARG*/ // Outputs m1_n, mreq_n, iorq_n, rd_n, wr_n, rfsh_n, halt_n, busak_n, A, dout, // Inputs reset_n, clk, wait_n, int_n, nmi_n, busrq_n, di ); parameter Mode = 0; // 0 => Z80, 1 => Fast Z80, 2 => 8080, 3 => GB parameter T2Write = 0; // 0 => wr_n active in T3, /=0 => wr_n active in T2 parameter IOWait = 1; // 0 => Single cycle I/O, 1 => Std I/O cycle input reset_n; input clk; input wait_n; input int_n; input nmi_n; input busrq_n; output m1_n; output mreq_n; output iorq_n; output rd_n; output wr_n; output rfsh_n; output halt_n; output busak_n; output [15:0] A; input [7:0] di; output [7:0] dout; reg mreq_n; reg iorq_n; reg rd_n; reg wr_n; reg nxt_mreq_n; reg nxt_iorq_n; reg nxt_rd_n; reg nxt_wr_n; wire cen; wire intcycle_n; wire no_read; wire write; wire iorq; reg [7:0] di_reg; wire [6:0] mcycle; wire [6:0] tstate; assign cen = 1; tv80_core #(Mode, IOWait) i_tv80_core ( .cen (cen), .m1_n (m1_n), .iorq (iorq), .no_read (no_read), .write (write), .rfsh_n (rfsh_n), .halt_n (halt_n), .wait_n (wait_n), .int_n (int_n), .nmi_n (nmi_n), .reset_n (reset_n), .busrq_n (busrq_n), .busak_n (busak_n), .clk (clk), .IntE (), .stop (), .A (A), .dinst (di), .di (di_reg), .dout (dout), .mc (mcycle), .ts (tstate), .intcycle_n (intcycle_n) ); always @* begin nxt_mreq_n = 1; nxt_rd_n = 1; nxt_iorq_n = 1; nxt_wr_n = 1; if (mcycle[0]) begin if (tstate[1] || tstate[2]) begin nxt_rd_n = ~ intcycle_n; nxt_mreq_n = ~ intcycle_n; nxt_iorq_n = intcycle_n; end end // if (mcycle[0]) else begin if ((tstate[1] || tstate[2]) && !no_read && !write) begin nxt_rd_n = 1'b0; nxt_iorq_n = ~ iorq; nxt_mreq_n = iorq; end if (T2Write == 0) begin if (tstate[2] && write) begin nxt_wr_n = 1'b0; nxt_iorq_n = ~ iorq; nxt_mreq_n = iorq; end end else begin if ((tstate[1] || (tstate[2] && !wait_n)) && write) begin nxt_wr_n = 1'b0; nxt_iorq_n = ~ iorq; nxt_mreq_n = iorq; end end // else: !if(T2write == 0) end // else: !if(mcycle[0]) end // always @ * always @(negedge clk) begin if (!reset_n) begin rd_n <= #1 1'b1; wr_n <= #1 1'b1; iorq_n <= #1 1'b1; mreq_n <= #1 1'b1; end else begin rd_n <= #1 nxt_rd_n; wr_n <= #1 nxt_wr_n; iorq_n <= #1 nxt_iorq_n; mreq_n <= #1 nxt_mreq_n; end // else: !if(!reset_n) end // always @ (posedge clk or negedge reset_n) always @(posedge clk) begin if (!reset_n) begin di_reg <= #1 0; end else begin if (tstate[2] && wait_n == 1'b1) di_reg <= #1 di; end // else: !if(!reset_n) end // always @ (posedge clk) endmodule // t80n
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