Apple-1-HW
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verilog-apple-one
mirror of https://github.com/alangarf/apple-one.git
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Added clear screen button

This commit is contained in:
Alan Garfield 2018-02-16 13:43:43 +11:00
parent ae59891f2e
commit b7f3f186f7
3 changed files with 68 additions and 51 deletions
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12
rtl/apple1.v
View File

@ -45,9 +45,10 @@ module apple1 #(
// Outputs to VGA display
output vga_h_sync, // hozizontal VGA sync pulse
output vga_v_sync, // vertical VGA sync pulse
output vga_red, // red VGA signal
output vga_grn, // green VGA signal
output vga_blu, // blue VGA signal
output vga_red, // red VGA signal
output vga_grn, // green VGA signal
output vga_blu, // blue VGA signal
input clr_screen, // clear screen button
// Debugging ports
output [15:0] pc_monitor // spy for program counter / debugging
@ -175,8 +176,6 @@ module apple1 #(
.uart_tx(uart_tx),
.uart_cts(uart_cts),
//.address({1'b1, ab[0]}), // for ps/2
//.address({1'b0, ab[0]}), // for vga
.address(ab[1:0]), // for uart
.w_en(we & uart_cs),
.din(dbo),
@ -214,7 +213,8 @@ module apple1 #(
.address(ab[0]),
.w_en(we & vga_cs),
.din(dbo),
.mode(vga_mode)
.mode(vga_mode),
.clr_screen(clr_screen)
);
// FIXME: REMOVE THIS

1
rtl/boards/ice40hx8k-b-evn/apple1_hx8k.v
View File

@ -104,6 +104,7 @@ module apple1_top #(
.vga_red(vga_red),
.vga_grn(vga_grn),
.vga_blu(vga_blu),
.clr_screen(~button[1]),
.pc_monitor(pc_monitor)
);

106
rtl/vga/vga.v
View File

@ -13,7 +13,8 @@ module vga #(
input address, // address bus
input w_en, // active high write enable strobe
input [7:0] din, // 8-bit data bus (input)
input [1:0] mode // 2-bit mode setting for pixel doubling
input [1:0] mode, // 2-bit mode setting for pixel doubling
input clr_screen // clear screen button
);
//////////////////////////////////////////////////////////////////////////
@ -60,9 +61,6 @@ module vga #(
wire [4:0] font_line;
wire font_out;
// Font ROM contents
parameter ROM_FILENAME = "";
// cpu control registers
reg char_seen;
@ -229,54 +227,72 @@ module vga #(
begin
vram_w_en <= 0;
// cursor overflow handling
if (h_cursor == 6'd40)
if (clr_screen)
begin
// return to top of screen
h_cursor <= 6'd0;
v_cursor <= v_cursor + 'd1;
end
v_cursor <= 5'd0;
if (v_cursor == vram_end_addr)
begin
vram_start_addr <= vram_start_addr + 'd1;
vram_end_addr <= vram_end_addr + 'd1;
end
vram_start_addr <= 5'd0;
vram_end_addr <= 5'd23;
if (address == 1'b0) // address low == TX register
begin
if (enable & w_en & ~char_seen)
begin
// incoming character
char_seen <= 1;
case(din)
8'h8D: begin
// handle carriage return
h_cursor <= 0;
v_cursor <= v_cursor + 'd1;
end
8'h7F: begin
// ignore the DDR call to the PIA
h_cursor <= 0;
end
default: begin
vram_w_addr <= cursor;
vram_din <= {~din[6], din[4:0]};
vram_w_en <= 1;
h_cursor <= h_cursor + 1;
end
endcase
end
else if(~enable & ~w_en)
char_seen <= 0;
// clear the screen
vram_w_addr <= {vram_v_addr, vram_h_addr};
vram_din <= 6'd32;
vram_w_en <= 1;
end
else
begin
vram_w_addr <= {vram_clr_addr, vram_h_addr};
vram_din <= 6'd32;
vram_w_en <= 1;
// cursor overflow handling
if (h_cursor == 6'd40)
begin
h_cursor <= 6'd0;
v_cursor <= v_cursor + 'd1;
end
if (v_cursor == vram_end_addr)
begin
vram_start_addr <= vram_start_addr + 'd1;
vram_end_addr <= vram_end_addr + 'd1;
end
if (address == 1'b0) // address low == TX register
begin
if (enable & w_en & ~char_seen)
begin
// incoming character
char_seen <= 1;
case(din)
8'h8D: begin
// handle carriage return
h_cursor <= 0;
v_cursor <= v_cursor + 'd1;
end
8'h9B,
8'h7F: begin
// ignore the escape key
h_cursor <= 0;
end
default: begin
vram_w_addr <= cursor;
vram_din <= {~din[6], din[4:0]};
vram_w_en <= 1;
h_cursor <= h_cursor + 1;
end
endcase
end
else if(~enable & ~w_en)
char_seen <= 0;
end
else
begin
vram_w_addr <= {vram_clr_addr, vram_h_addr};
vram_din <= 6'd32;
vram_w_en <= 1;
end
end
end
end