X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/7c1b9e8ea3a9ec0d0c00009df9212a1829e072ec..1eefdc8e89a69963b1c1a084fe4ecec844997293:/System.v diff --git a/System.v b/System.v index b1d4c3d..62683d3 100644 --- a/System.v +++ b/System.v @@ -29,14 +29,20 @@ module BootstrapROM( reg rdlatch = 0; reg [7:0] addrlatch = 0; - reg [7:0] brom [255:0]; - initial $readmemh("bootstrap.hex", brom); + reg romno = 0, romnotmp = 0; + reg [7:0] brom0 [255:0]; + reg [7:0] brom1 [255:0]; + + initial $readmemh("fpgaboot.hex", brom0); + initial $readmemh("gbboot.hex", brom1); wire decode = address[15:8] == 0; - wire [7:0] odata = brom[addrlatch]; + wire [7:0] odata = (romno == 0) ? brom0[addrlatch] : brom1[addrlatch]; always @(posedge clk) begin rdlatch <= rd && decode; addrlatch <= address[7:0]; + if (wr && decode) romnotmp <= data[0]; + if (rd && address == 16'h0000) romno <= romnotmp; /* Latch when the program restarts. */ end assign data = rdlatch ? odata : 8'bzzzzzzzz; endmodule @@ -86,6 +92,8 @@ module CellularRAM( reg [7:0] progaddrh, progaddrm, progaddrl; + reg [22:0] progaddr; + assign cr_nADV = 0; /* Addresses are always valid! :D */ assign cr_nCE = 0; /* The chip is enabled */ assign cr_nLB = 0; /* Lower byte is enabled */ @@ -101,7 +109,7 @@ module CellularRAM( assign cr_DQ = (~cr_nOE) ? 16'bzzzzzzzzzzzzzzzz : {8'b0, datalatch}; assign cr_A = (addrlatch[15:14] == 2'b00) ? /* extrom */ {9'b0,addrlatch[13:0]} : (addrlatch[15:13] == 3'b101) ? {1'b1, 9'b0, addrlatch[12:0]} : - (addrlatch == ADDR_PROGDATA) ? {progaddrh[6:0], progaddrm[7:0], progaddrl[7:0]} : + (addrlatch == ADDR_PROGDATA) ? progaddr : 23'b0; reg [7:0] regbuf; @@ -111,6 +119,10 @@ module CellularRAM( ADDR_PROGADDRH: if (wr) progaddrh <= data; ADDR_PROGADDRM: if (wr) progaddrm <= data; ADDR_PROGADDRL: if (wr) progaddrl <= data; + ADDR_PROGDATA: if (rd || wr) begin + progaddr <= {progaddrh[6:0], progaddrm[7:0], progaddr[7:0]}; + {progaddrh[6:0], progaddrm[7:0], progaddr[7:0]} <= {progaddrh[6:0], progaddrm[7:0], progaddr[7:0]} + 23'b1; + end endcase rdlatch <= rd; wrlatch <= wr;