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Redo overlay bit to remove ODCSr register

This commit is contained in:
Zane Kaminski 2023-04-09 22:50:24 -04:00
parent 8fc04a86a8
commit ec89576fad
1 changed files with 19 additions and 23 deletions
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42
cpld/CS.v
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@ -10,41 +10,37 @@ module CS(
/* Overlay control */
reg nOverlay = 0; wire Overlay = !nOverlay;
reg ODCSr;
always @(posedge CLK) begin
ODCSr <= ROMCS4X && BACT;
if (!BACT) begin
if (!nRES) nOverlay <= 0;
else if (ODCSr) nOverlay <= 1;
end
if (!BACT && !nRES) nOverlay <= 0;
else if (BACT && ROMCS4X) nOverlay <= 1;
end
/* ROM select signals */
assign ROMCS4X = A[23:20]==4'h4;
assign ROMCS = ((A[23:20]==4'h0) && Overlay) || ROMCS4X;
assign ROMCS = (A[23:20]==4'h0 && Overlay) || ROMCS4X;
assign SndROMCS = ROMCS4X &&
(A[20:8]==12'h36C || A[20:8]==12'h36D || A[20:8]==12'h36F);
/* RAM select signals */
assign RAMCS0X = A[23:22]==2'b00;
assign RAMCS = RAMCS0X && !Overlay;
wire VidRAMCSWR64k = RAMCS0X && !nWE && (A[23:20]==4'h3) && (A[19:16]==4'hF); // 3F0000-3FFFFF
wire VidRAMCSWR64k = RAMCS0X && !nWE && A[23:16]==8'h3F; // 3F0000-3FFFFF
wire VidRAMCSWR = VidRAMCSWR64k && (
(A[15:12]==4'h2) || // 1792 bytes RAM, 2304 bytes video
(A[15:12]==4'h3) || // 4096 bytes video
(A[15:12]==4'h4) || // 4096 bytes video
(A[15:12]==4'h5) || // 4096 bytes video
(A[15:12]==4'h6) || // 4096 bytes video
(A[15:12]==4'h7) || // 3200 bytes video, 896 bytes RAM
(A[15:12]==4'hA) || // 256 bytes RAM, 768 bytes sound, 768 bytes RAM, 2304 bytes video
(A[15:12]==4'hB) || // 4096 bytes video
(A[15:12]==4'hC) || // 4096 bytes video
(A[15:12]==4'hD) || // 4096 bytes video
(A[15:12]==4'hE) || // 4096 bytes video
(A[15:12]==4'hF)); // 3200 bytes video, 128 bytes RAM (system error space), 768 bytes sound
A[15:12]==4'h2 || // 1792 bytes RAM, 2304 bytes video
A[15:12]==4'h3 || // 4096 bytes video
A[15:12]==4'h4 || // 4096 bytes video
A[15:12]==4'h5 || // 4096 bytes video
A[15:12]==4'h6 || // 4096 bytes video
A[15:12]==4'h7 || // 3200 bytes video, 896 bytes RAM
A[15:12]==4'hA || // 256 bytes RAM, 768 bytes sound, 768 bytes RAM, 2304 bytes video
A[15:12]==4'hB || // 4096 bytes video
A[15:12]==4'hC || // 4096 bytes video
A[15:12]==4'hD || // 4096 bytes video
A[15:12]==4'hE || // 4096 bytes video
A[15:12]==4'hF); // 3200 bytes video, 128 bytes RAM (system error space), 768 bytes sound
assign SndRAMCSWR = VidRAMCSWR64k && (
((A[15:12]==4'hF) && ((A[11:8]==4'hD) || (A[11:8]==4'hE) || (A[11:8]==4'hF))) ||
((A[15:12]==4'hA) && ((A[11:8]==4'h1) || (A[11:8]==4'h2) || (A[11:8]==4'h3))));
((A[15:12]==4'hF) && (A[11:8]==4'hD || A[11:8]==4'hE || A[11:8]==4'hF)) ||
((A[15:12]==4'hA) && (A[11:8]==4'h1 || A[11:8]==4'h2 || A[11:8]==4'h3)));
/* Select signals - IOB domain */
assign IACS = A[23:16]==8'hFF; // IACK
@ -60,6 +56,6 @@ module CS(
A[23:20]==4'h6 || // empty
A[23:20]==4'h5 || // SCSI
(A[23:20]==4'h4 && Overlay) || // ROM once
VidRAMCSWR; // Write to video RAM
VidRAMCSWR; // Write to video RAM
assign IOPWCS = VidRAMCSWR;
endmodule