.gitignore

@@ -2,4 +2,3 @@
 *.vpi
 *.lx2
 *.o
-*.swp

8086_documentation.md

@@ -11,7 +11,7 @@ Instructions vary from 1 to 6 bytes.
 
 On some instructions:
 
-* **S**-bit : An 8-bit 2's complement number. It can be extended to a 16-bit 2’s complement number depending on the W-bit by making all of the bits in the higher-order byte equal the most significant bit in the low order byte. This is known as sign extension.
+* **S**-bit : An 8-bit 2’s complement number. It can be extended to a 16-bit 2’s complement number depending on the W-bit by making all of the bits in the higher-order byte equal the most significant bit in the low order byte. This is known as sign extension.
 
 | S   | W   |    Operation    |
 | --- | --- |  -------------- |
@@ -46,13 +46,3 @@ The second byte of the instruction usually identifies the instruction's operands
 |101  | [DI]                                     | [DI] + d8                                   | [DI] + d16                                   |    CH                       | BP                          |
 |110  | d16 (direct)                             | [BP] + d8                                   | [BP] + d16                                   |    DH                       | SI                          |
 |111  | [BX]                                     | [BX] + d8                                   | [BX] + d16                                   |    BH                       | DI                          |
-
-Example instructions:
-
-|  Bytecode  |   AT&T Syntax   |                         meaning                            |
-| ---------- | --------------- | ---------------------------------------------------------- |
-|81 c0 aa 55 | add $0x55aa,%ax | write 0x55aa to register ax                                |
-|03 06 aa 55 | add 0x55aa,%ax  | write the contents of memory locaton 0x55aa to register ax |
-|fe c0       | inc %al         | increment register al                                      |
-|ff c0       | inc %ax         | increment register ax                                      |
-|40          | inc %ax         | increment register ax                                      |

cpu/boot_code.txt

@@ -1,7 +1,7 @@
 // 0x00000000
-81C0
+55AA
-AA55
+0000
-FEC0
+0000
 0000
 0000
 0000

cpu/gtkwave_savefile.gtkw

@@ -1,13 +1,13 @@
 [*]
 [*] GTKWave Analyzer v3.3.104 (w)1999-2020 BSI
-[*] Wed Feb  8 23:43:14 2023
+[*] Wed Feb  8 11:44:52 2023
 [*]
 [dumpfile] "/home/user/UNI_DATA/COMS30046_2022_TB-2/projects/9086/cpu/test.lx2"
-[dumpfile_mtime] "Wed Feb  8 23:42:51 2023"
+[dumpfile_mtime] "Wed Feb  8 11:44:20 2023"
-[dumpfile_size] 470
+[dumpfile_size] 430
 [savefile] "/home/user/UNI_DATA/COMS30046_2022_TB-2/projects/9086/cpu/gtkwave_savefile.gtkw"
 [timestart] 0
-[size] 1534 1059
+[size] 1342 1059
 [pos] -1 -1
 *-20.795050 2883000 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
 [treeopen] tb.
@@ -19,14 +19,12 @@
 tb.p.clock[0]
 tb.p.reset[0]
 tb.p.start[0]
-@29
+tb.p.state[1:0]
-tb.p.state[2:0]
-@28
 tb.p.instruction_finished[0]
 @22
 tb.p.external_address_bus[19:0]
 tb.p.external_data_bus[15:0]
-@28
+@29
 tb.p.read[0]
 [pattern_trace] 1
 [pattern_trace] 0

cpu/processor.v

@@ -54,13 +54,13 @@ endmodule
 
 module processor ( input clock, input reset , output reg [19:0] external_address_bus, inout [15:0] external_data_bus,output reg read, output reg write);
 /* State */
-reg [2:0] state;
+reg [1:0] state;
 reg start=0;
 reg instruction_finished;
 
 /* Registers */
 reg [19:0] ProgCount;
-reg [14:0] CIR;
+
 
 /* RESET LOGIC */
 always @(negedge reset) begin
@@ -75,29 +75,29 @@ end
 
 /* CLOCK LOGIC */
 always @(posedge clock) begin
-	if(instruction_finished)
+	if(instruction_finished) begin 
 		state =0;
-	else
+	end else begin
-		if (clock && start==1)
+		if (clock && start==1) begin
 			state=state+1;
+		end
+	end
 end
 
 always @(state) begin
-	if (state==5)
+	if (state==2) begin
 		instruction_finished=1;
-	else
+	end else begin
 		instruction_finished=0;
+	end
 end
 
 /* Processor stages */
 always @(state) begin
-	if (state=='b000) begin
+	if (state==0) begin
 		external_address_bus <= ProgCount;
 		read <= 0;
 		write <= 1;
-	end else if ( state=='b001 ) begin
-		CIR <= external_data_bus;
-		ProgCount=ProgCount+1;
 	end
 end
 

cpu/testbench.v

@@ -9,8 +9,6 @@ wire rd,wr,romcs;
 processor p(clock,reset,address_bus,data_bus,rd,wr);
 rom bootrom(address_bus,data_bus,rd,romcs);
 
-`define CPU_SPEED 1000
-
 clock_gen #(.FREQ(1000)) u1(clk_enable, clock);
 
 assign romcs=0;
@@ -24,7 +22,7 @@ initial begin
 	reset = 0;
 	#(100) 
 	reset = 1;
-	#(`CPU_SPEED*30)
+	#(10000)
 
 	#50 $finish;
 end