GR8RAM/cpld/GR8RAM.v
2021-04-21 20:06:56 -04:00

569 lines
15 KiB
Verilog

module GR8RAM(C25M, PHI0, nRES, nRESout, SetFW,
INTin, INTout, DMAin, DMAout,
nNMIout, nIRQout, nRDYout, nINHout, RWout, nDMAout,
RA, nWE, RD, RAdir, RDdir, nIOSEL, nDEVSEL, nIOSTRB,
SBA, SA, nRCS, nRAS, nCAS, nSWE, DQML, DQMH, RCKE, SD,
nFCS, FCK, MISO, MOSI);
/* Clock signals */
input C25M, PHI0;
reg PHI0r1, PHI0r2;
always @(posedge C25M) begin PHI0r1 <= PHI0; PHI0r2 <= PHI0r1; end
/* Reset filter */
input nRES;
reg [3:0] nRESf = 0;
reg nRESr = 0;
always @(posedge C25M) begin
nRESf[3:0] <= { nRESf[2:0], nRES };
nRESr <= nRESf[3] || nRESf[2] || nRESf[1] || nRESf[0];
end
/* Firmware select */
input [1:0] SetFW;
reg [1:0] SetFWr;
reg SetFWLoaded = 0;
always @(posedge C25M) begin
if (~SetFWLoaded) begin
SetFWLoaded <= 1;
SetFWr[1:0] <= SetFW[1:0];
end
end
wire [1:0] SetROM = ~SetFWr[1:0];
wire SetEN16MB = SetROM[1:0]==2'b11;
wire SetEN24bit = SetROM[1];
/* State counter from PHI0 rising edge */
reg [3:0] PS = 0;
wire PSStart = PS==0 && PHI0r1 && ~PHI0r2;
always @(posedge C25M) begin
if (PSStart) PS <= 1;
else if (PS==0) PS <= 0;
else PS <= PS+1;
end
/* Long state counter: counts from 0 to $3FFF */
reg [13:0] LS = 0;
always @(posedge C25M) begin if (PS==15) LS <= LS+1; end
/* Init state */
output reg nRESout = 0;
reg [2:0] IS = 0;
always @(posedge C25M) begin
if (IS==7) nRESout <= 1;
else if (PS==15) begin
if (LS==14'h1FCE) IS <= 1; // PC all + load mode
else if (LS==14'h1FCF) IS <= 4; // AREF pause, SPI select
else if (LS==14'h1FFA) IS <= 5; // SPI flash command
else if (LS==14'h1FFF) IS <= 6; // Flash load driver
else if (LS==14'h3FFF) IS <= 7; // Operating mode
end
end
/* Apple IO area select signals */
input nIOSEL, nDEVSEL, nIOSTRB;
/* Apple address bus */
input [15:0] RA; input nWE;
reg [11:0] RAr; reg nWEr;
reg CXXXr;
always @(posedge PHI0) begin
CXXXr <= RA[15:12]==4'hC;
RAr[11:0] <= RA[11:0];
nWEr <= nWE;
end
/* Apple select signals */
wire ROMSpecRD = CXXXr && RAr[11:8]!=4'h0 && nWEr && ((RAr[11] && IOROMEN) || (~RAr[11]));
wire REGSpecSEL = CXXXr && RAr[11:8]==4'h0 && RAr[7] && REGEN;
wire BankSpecSEL = REGSpecSEL && RAr[3:0]==4'hF;
wire RAMRegSpecSEL = REGSpecSEL && RAr[3:0]==4'h3;
wire RAMSpecSEL = RAMRegSpecSEL && (~SetEN24bit || SetEN16MB || ~Addr[23]);
wire AddrHSpecSEL = REGSpecSEL && RAr[3:0]==4'h2;
wire AddrMSpecSEL = REGSpecSEL && RAr[3:0]==4'h1;
wire AddrLSpecSEL = REGSpecSEL && RAr[3:0]==4'h0;
wire BankSEL = REGEN && ~nDEVSEL && BankSpecSEL;
wire RAMRegSEL = ~nDEVSEL && RAMRegSpecSEL;
wire RAMSEL = ~nDEVSEL && RAMSpecSEL;
wire RAMWR = RAMSEL && ~nWEr;
wire AddrHSEL = REGEN && ~nDEVSEL && AddrHSpecSEL;
wire AddrMSEL = REGEN && ~nDEVSEL && AddrMSpecSEL;
wire AddrLSEL = REGEN && ~nDEVSEL && AddrLSpecSEL;
/* IOROMEN and REGEN control */
reg IOROMEN = 0;
reg REGEN = 0;
reg nIOSTRBr;
wire IOROMRES = RAr[10:0]==11'h7FF && ~nIOSTRB && ~nIOSTRBr;
always @(posedge C25M, negedge nRESr) begin
if (~nRESr) REGEN <= 0;
else if (PS==8 && ~nIOSEL) REGEN <= 1;
end
always @(posedge C25M) begin
nIOSTRBr <= nIOSTRB;
if (~nRESr) IOROMEN <= 0;
else if (PS==8 && IOROMRES) IOROMEN <= 0;
else if (PS==8 && ~nIOSEL) IOROMEN <= 1;
end
/* Apple data bus */
inout [7:0] RD = RDdir ? 8'bZ : RDD[7:0];
reg [7:0] RDD;
output RDdir = ~(PHI0r2 && nWE && PHI0 &&
(~nDEVSEL || ~nIOSEL || (~nIOSTRB && IOROMEN && RA[10:0]!=11'h7FF)));
/* Slinky address registers */
reg [23:0] Addr = 0;
reg AddrIncL = 0;
reg AddrIncM = 0;
reg AddrIncH = 0;
always @(posedge C25M, negedge nRESr) begin
if (~nRESr) begin
Addr[23:0] <= 24'h000000;
AddrIncL <= 0;
AddrIncM <= 0;
AddrIncH <= 0;
end else begin
if (PS==8 && RAMRegSEL) AddrIncL <= 1;
else AddrIncL <= 0;
if (PS==8 && AddrLSEL && ~nWEr) begin
Addr[7:0] <= RD[7:0];
AddrIncM <= Addr[7] && ~RD[7];
end else if (AddrIncL) begin
Addr[7:0] <= Addr[7:0]+1;
AddrIncM <= Addr[7:0]==8'hFF;
end else AddrIncM <= 0;
if (PS==8 && AddrMSEL && ~nWEr) begin
Addr[15:8] <= RD[7:0];
AddrIncH <= Addr[15] && ~RD[7];
end else if (AddrIncM) begin
Addr[15:8] <= Addr[15:8]+1;
AddrIncH <= Addr[15:8]==8'hFF;
end else AddrIncH <= 0;
if (PS==8 && AddrHSEL && ~nWEr) begin
Addr[23:16] <= RD[7:0];
end else if (AddrIncH) begin
Addr[23:16] <= Addr[23:16]+1;
end
end
end
/* ROM bank register */
reg Bank = 0;
always @(posedge C25M, negedge nRESr) begin
if (~nRESr) Bank <= 0;
else if (PS==8 && BankSEL && ~nWEr) begin
Bank <= RD[0];
end
end
/* SPI flash control signals */
output nFCS = FCKOE ? ~FCS : 1'bZ;
reg FCS = 0;
output FCK = FCKOE ? FCKout : 1'bZ;
reg FCKOE = 0;
reg FCKout = 0;
inout MOSI = MOSIOE ? MOSIout : 1'bZ;
reg MOSIOE = 0;
input MISO;
always @(posedge C25M) begin
case (PS[3:0])
0: begin // NOP CKE
FCKout <= 1'b1;
end 1: begin // ACT
FCKout <= ~(IS==5 || IS==6);
end 2: begin // RD
FCKout <= 1'b1;
end 3: begin // NOP CKE
FCKout <= ~(IS==5 || IS==6);
end 4: begin // NOP CKE
FCKout <= 1'b1;
end 5: begin // NOP CKE
FCKout <= ~(IS==5 || IS==6);
end 6: begin // NOP CKE
FCKout <= 1'b1;
end 7: begin // NOP CKE
FCKout <= ~(IS==5 || IS==6);
end 8: begin // WR AP
FCKout <= 1'b1;
end 9: begin // NOP CKE
FCKout <= ~(IS==5);
end 10: begin // PC all
FCKout <= 1'b1;
end 11: begin // AREF
FCKout <= ~(IS==5);
end 12: begin // NOP CKE
FCKout <= 1'b1;
end 13: begin // NOP CKE
FCKout <= ~(IS==5);
end 14: begin // NOP CKE
FCKout <= 1'b1;
end 15: begin // NOP CKE
FCKout <= ~(IS==5);
end
endcase
FCS <= IS==4 || IS==5 || IS==6;
MOSIOE <= IS==5;
FCKOE <= IS==1 || IS==4 || IS==5 || IS==6 || IS==7;
end
/* SPI flash MOSI control */
reg MOSIout = 0;
always @(posedge C25M) begin
case (PS[3:0])
1: begin
case (LS[2:0])
3'h3: MOSIout <= 1'b0; // Command bit 7
3'h4: MOSIout <= 1'b0; // Address bit 23
3'h5: MOSIout <= 1'b0; // Address bit 15
3'h6: MOSIout <= 1'b0; // Address bit 7
default MOSIout <= 1'b0;
endcase
end 3: begin
case (LS[2:0])
3'h3: MOSIout <= 1'b0; // Command bit 6
3'h4: MOSIout <= 1'b0; // Address bit 22
3'h5: MOSIout <= SetROM[1]; // Address bit 14
3'h6: MOSIout <= 1'b0; // Address bit 6
default MOSIout <= 1'b0;
endcase
end 5: begin
case (LS[2:0])
3'h3: MOSIout <= 1'b1; // Command bit 5
3'h4: MOSIout <= 1'b0; // Address bit 21
3'h5: MOSIout <= SetROM[0]; // Address bit 13
3'h6: MOSIout <= 1'b0; // Address bit 5
default MOSIout <= 1'b0;
endcase
end 7: begin
case (LS[2:0])
3'h3: MOSIout <= 1'b1; // Command bit 4
3'h4: MOSIout <= 1'b0; // Address bit 20
3'h5: MOSIout <= 1'b0; // Address bit 12
3'h6: MOSIout <= 1'b0; // Address bit 4
default MOSIout <= 1'b0;
endcase
end 9: begin
case (LS[2:0])
3'h3: MOSIout <= 1'b1; // Command bit 3
3'h4: MOSIout <= 1'b0; // Address bit 19
3'h5: MOSIout <= 1'b0; // Address bit 11
3'h6: MOSIout <= 1'b0; // Address bit 3
default MOSIout <= 1'b0;
endcase
end 11: begin
case (LS[2:0])
3'h3: MOSIout <= 1'b0; // Command bit 2
3'h4: MOSIout <= 1'b0; // Address bit 18
3'h5: MOSIout <= 1'b0; // Address bit 10
3'h6: MOSIout <= 1'b0; // Address bit 2
default MOSIout <= 1'b0;
endcase
end 13: begin
case (LS[2:0])
3'h3: MOSIout <= 1'b1; // Command bit 1
3'h4: MOSIout <= 1'b0; // Address bit 16
3'h5: MOSIout <= 1'b0; // Address bit 9
3'h6: MOSIout <= 1'b0; // Address bit 1
default MOSIout <= 1'b0;
endcase
end 15: begin
case (LS[2:0])
3'h3: MOSIout <= 1'b1; // Command bit 0
3'h4: MOSIout <= 1'b0; // Address bit 15
3'h5: MOSIout <= 1'b0; // Address bit 7
3'h6: MOSIout <= 1'b0; // Address bit 0
default MOSIout <= 1'b0;
endcase
end
endcase
end
/* SDRAM data bus */
inout [7:0] SD = SDOE ? WRD[7:0] : 8'bZ;
reg [7:0] WRD;
reg SDOE = 0;
always @(posedge C25M) begin
case (PS[3:0])
0: begin // NOP CKE
if (IS==6) WRD[7:0] <= { WRD[5:0], MISO, MOSI };
else WRD[7:0] <= RD[7:0];
end 1: begin // ACT
end 2: begin // RD
if (IS==6) WRD[7:0] <= { WRD[5:0], MISO, MOSI };
else WRD[7:0] <= RD[7:0];
end 3: begin // NOP CKE
end 4: begin // NOP CKE
if (IS==6) WRD[7:0] <= { WRD[5:0], MISO, MOSI };
else WRD[7:0] <= RD[7:0];
end 5: begin // NOP CKE
end 6: begin // NOP CKE
if (IS==6) WRD[7:0] <= { WRD[5:0], MISO, MOSI };
else WRD[7:0] <= RD[7:0];
end 7: begin // NOP CKE
end 8: begin // WR AP
if (IS==6) WRD[7:0] <= { WRD[5:0], MISO, MOSI };
else WRD[7:0] <= RD[7:0];
end 9: begin // NOP CKE
end 10: begin // PC all
if (IS==6) WRD[7:0] <= { WRD[5:0], MISO, MOSI };
else WRD[7:0] <= RD[7:0];
end 11: begin // AREF
end 12: begin // NOP CKE
if (IS==6) WRD[7:0] <= { WRD[5:0], MISO, MOSI };
else WRD[7:0] <= RD[7:0];
end 13: begin // NOP CKE
end 14: begin // NOP CKE
if (IS==6) WRD[7:0] <= { WRD[5:0], MISO, MOSI };
else WRD[7:0] <= RD[7:0];
end 15: begin // NOP CKE
end
endcase
end
/* Apple data bus from SDRAM */
always @(negedge C25M) begin
if (PS==5) begin
if (AddrLSpecSEL) RDD[7:0] <= Addr[7:0];
else if (AddrMSpecSEL) RDD[7:0] <= Addr[15:8];
else if (AddrHSpecSEL) RDD[7:0] <= { SetEN24bit ? Addr[23:20] : 4'hF, Addr[19:16] };
else RDD[7:0] <= SD[7:0];
end
end
/* SDRAM command */
output reg RCKE = 1;
output reg nRCS = 1;
output reg nRAS = 1;
output reg nCAS = 1;
output reg nSWE = 1;
wire RefReqd = LS[1:0] == 2'b11;
always @(posedge C25M) begin
case (PS[3:0])
0: begin // NOP CKE / NOP CKD
RCKE <= PSStart && (IS==6 || (IS==7 && (ROMSpecRD || RAMSpecSEL)));
nRCS <= 1;
nRAS <= 1;
nCAS <= 1;
nSWE <= 1;
SDOE <= 0;
end 1: begin // ACT CKE / NOP CKD (ACT)
RCKE <= IS==6 || (IS==7 && (ROMSpecRD || RAMSpecSEL));
nRCS <= ~(IS==6 || (IS==7 && (ROMSpecRD || RAMSpecSEL)));
nRAS <= 0;
nCAS <= 1;
nSWE <= 1;
SDOE <= 0;
end 2: begin // RD CKE / NOP CKD (RD)
RCKE <= IS==7 && nWEr && (ROMSpecRD || RAMSpecSEL);
nRCS <= ~(IS==7 && nWEr && (ROMSpecRD || RAMSpecSEL));
nRAS <= 1;
nCAS <= 0;
nSWE <= 1;
SDOE <= 0;
end 3: begin // NOP CKE / CKD
RCKE <= IS==7 && nWEr && (ROMSpecRD || RAMSpecSEL);
nRCS <= 1;
nRAS <= 1;
nCAS <= 1;
nSWE <= 1;
SDOE <= 0;
end 4: begin // NOP CKD
RCKE <= 0;
nRCS <= 1;
nRAS <= 1;
nCAS <= 1;
nSWE <= 1;
SDOE <= 0;
end 5: begin // NOP CKD
RCKE <= 0;
nRCS <= 1;
nRAS <= 1;
nCAS <= 1;
nSWE <= 1;
SDOE <= 0;
end 6: begin // NOP CKD
RCKE <= 0;
nRCS <= 1;
nRAS <= 1;
nCAS <= 1;
nSWE <= 1;
SDOE <= 0;
end 7: begin // NOP CKE / CKD
RCKE <= IS==6 || (RAMWR && IS==7);
nRCS <= 1;
nRAS <= 1;
nCAS <= 1;
nSWE <= 1;
SDOE <= 0;
end 8: begin // WR AP CKE / NOP CKD (WR AP)
RCKE <= IS==6 || (RAMWR && IS==7);
nRCS <= ~(IS==6 || (RAMWR && IS==7));
nRAS <= 1;
nCAS <= 0;
nSWE <= 0;
SDOE <= IS==6 || (RAMWR && IS==7);
end 9: begin // NOP CKE / NOP CKD
RCKE <= 1;
nRCS <= 1;
nRAS <= 1;
nCAS <= 1;
nSWE <= 1;
SDOE <= 0;
end 10: begin // PC all CKE / PC all CKD
RCKE <= IS==1 || IS==4 || IS==5 || IS==6 || (IS==7 && RefReqd);
nRCS <= 0;
nRAS <= 0;
nCAS <= 1;
nSWE <= 0;
SDOE <= 0;
end 11: begin // LDM CKE / AREF CKE / NOP CKD
RCKE <= IS==1 || IS==4 || IS==5 || IS==6 || (IS==7 && RefReqd);
nRCS <= ~(IS==1 || IS==4 || IS==5 || IS==6 || (IS==7 && RefReqd));
nRAS <= 0;
nCAS <= 0;
nSWE <= ~(IS==1);
SDOE <= 0;
end default: begin // NOP CKD
RCKE <= 0;
nRCS <= 1;
nRAS <= 1;
nCAS <= 1;
nSWE <= 1;
SDOE <= 0;
end
endcase
end
/* SDRAM address */
output reg DQML = 1;
output reg DQMH = 1;
output reg [1:0] SBA;
output reg [12:0] SA;
always @(posedge C25M) begin
case (PS[3:0])
0: begin // NOP CKE
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0011000100000;
end 1: begin // ACT
DQML <= 1'b1;
DQMH <= 1'b1;
if (IS==6) begin
SBA[1:0] <= { 2'b10 };
SA[12:0] <= { 10'b0011000100, LS[12:10] };
end else if (RAMSpecSEL) begin
SBA[1:0] <= { 1'b0, SetEN24bit ? Addr[23] : 1'b0 };
SA[12:10] <= SetEN24bit ? Addr[22:20] : 3'b000;
SA[9:0] <= Addr[19:10];
end else begin
SBA[1:0] <= 2'b10;
SA[12:0] <= { 10'b0011000100, Bank, RAr[11:10] };
end
end 2: begin // RD
if (RAMSpecSEL) begin
SBA[1:0] <= { 1'b0, SetEN24bit ? Addr[23] : 1'b0 };
SA[12:0] <= { 4'b0011, Addr[9:1] };
DQML <= Addr[0];
DQMH <= ~Addr[0];
end else begin
SBA[1:0] <= 2'b10;
SA[12:0] <= { 4'b0011, RAr[9:1]};
DQML <= RAr[0];
DQMH <= ~RAr[0];
end
end 3: begin // NOP CKE
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0011000100000;
end 4: begin // NOP CKE
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0011000100000;
end 5: begin // NOP CKE
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0011000100000;
end 6: begin // NOP CKE
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0011000100000;
end 7: begin // NOP CKE
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0011000100000;
end 8: begin // WR AP
if (IS==6) begin
SBA[1:0] <= 2'b10;
SA[12:0] <= { 4'b0011, LS[9:1] };
DQML <= LS[0];
DQMH <= ~LS[0];
end else begin
SBA[1:0] <= { 1'b0, SetEN24bit ? Addr[23] : 1'b0 };
SA[12:0] <= { 4'b0011, Addr[9:1] };
DQML <= Addr[0];
DQMH <= ~Addr[0];
end
end 9: begin // NOP CKE
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0011000100000;
end 10: begin // PC all
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0011000100000;
end 11: begin // AREF / load mode
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0001000100000;
end 12: begin // NOP CKE
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0011000100000;
end 13: begin // NOP CKE
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0011000100000;
end 14: begin // NOP CKE
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0011000100000;
end 15: begin // NOP CKE
DQML <= 1'b1;
DQMH <= 1'b1;
SBA[1:0] <= 2'b00;
SA[12:0] <= 13'b0011000100000;
end
endcase
end
/* DMA/INT in/out */
input INTin, DMAin;
output INTout = INTin;
output DMAout = DMAin;
/* Unused Pins */
output RAdir = 1;
output nDMAout = 1;
output nNMIout = 1;
output nINHout = 1;
output nRDYout = 1;
output nIRQout = 1;
output RWout = 1;
endmodule