From 9de83fd7c1135750e96c602c1590523985f0a68b Mon Sep 17 00:00:00 2001
From: "(Tim) Efthimis Kritikos" <efkf@firemail.cc>
Date: Wed, 8 Mar 2023 07:26:28 +0000
Subject: [PATCH] Added partial support for the software interrupt INT
 instruction

---
 Makefile                            |  3 +
 boot_code/brainfuck_compiled.asm    |  5 ++
 boot_code/brainfuck_interpreted.asm |  5 ++
 boot_code/brainfuck_mandelbrot.asm  |  5 ++
 common.mk                           |  2 +-
 system/alu.v                        | 10 +--
 system/alu_header.v                 |  1 +
 system/boot_code.asm                |  9 +++
 system/decoder.v                    | 96 ++++++++++++++++++++---------
 system/processor.v                  | 18 +++++-
 system/system.v                     |  1 +
 system/ucode.txt                    | 74 +++++++++++++---------
 system/ucode_header.v               | 17 ++---
 13 files changed, 166 insertions(+), 80 deletions(-)

diff --git a/Makefile b/Makefile
index 3c9059d..b4d42d4 100644
--- a/Makefile
+++ b/Makefile
@@ -23,6 +23,9 @@ GTKWSAVE=./gtkwave_savefile.gtkw
 MICROCODE=system/ucode.txt
 BOOTABLES=boot_code/brainfuck_compiled.txt boot_code/brainfuck_interpreted.txt ${BOOT_CODE}
 
+shim:
+	@echo The processor\'s output handling is being rewritten so the usual mandelbrot program isn\'t working. please git checkout d93c92c00572d812c76d1b42969741d8cfce8d4d
+
 NO_ASM=1
 include common.mk
 
diff --git a/boot_code/brainfuck_compiled.asm b/boot_code/brainfuck_compiled.asm
index 0c7d7ba..0bb9eb3 100644
--- a/boot_code/brainfuck_compiled.asm
+++ b/boot_code/brainfuck_compiled.asm
@@ -1,5 +1,10 @@
+org 0x100
 INCLUDE brainfuck_compiler_v1.asm
 
 prog:
 INCLUDE hello_9086.bf.asm
 output_program:
+
+.ORG 0xFFF0
+MOV AX,#0x0100
+JMP AX
diff --git a/boot_code/brainfuck_interpreted.asm b/boot_code/brainfuck_interpreted.asm
index 0dda918..2b8c8ce 100644
--- a/boot_code/brainfuck_interpreted.asm
+++ b/boot_code/brainfuck_interpreted.asm
@@ -1,4 +1,9 @@
+ORG 0x100
 INCLUDE brainfuck_interpreter_v0.asm
 
 prog:
 INCLUDE hello_9086.bf.asm
+
+.ORG 0xFFF0
+MOV AX,#0x0100
+JMP AX
diff --git a/boot_code/brainfuck_mandelbrot.asm b/boot_code/brainfuck_mandelbrot.asm
index d261bd9..3fff94a 100644
--- a/boot_code/brainfuck_mandelbrot.asm
+++ b/boot_code/brainfuck_mandelbrot.asm
@@ -1,6 +1,11 @@
+ORG 0x100
 INCLUDE brainfuck_compiler_v1.asm
 
 prog:
 INCLUDE mandelbrot.bf.asm
 
 output_program:
+
+.ORG 0xFFF0
+MOV AX,#0x0100
+JMP AX
diff --git a/common.mk b/common.mk
index 8dc8ef1..d3d7f30 100644
--- a/common.mk
+++ b/common.mk
@@ -35,7 +35,7 @@ disas: $(subst .txt,.disas,${BOOT_CODE})
 
 # Assembling code
 %.txt:%.bin
-	${Q}dd if=/dev/zero bs=1 count=32768 of="$(subst .bin,.stage,$<)" status=none
+	${Q}dd if=/dev/zero bs=1 count=65536 of="$(subst .bin,.stage,$<)" status=none
 	${Q}dd if="$<" of="$(subst .bin,.stage,$<)" conv=notrunc,nocreat status=none
 	${Q}xxd -ps -c 2 "$(subst .bin,.stage,$<)" > "$@"
 	${Q}rm "$(subst .bin,.stage,$<)"
diff --git a/system/alu.v b/system/alu.v
index 4ae3a79..53ebac8 100644
--- a/system/alu.v
+++ b/system/alu.v
@@ -38,10 +38,7 @@ always @ ( * ) begin
 			`ALU_OP_AND: begin C_FLAG=0;OUT=A&B; end
 			`ALU_OP_OR:  begin C_FLAG=0;OUT=A|B; end
 			`ALU_OP_XOR: begin C_FLAG=0;OUT=A^B; end
-			default:begin
-				OUT=0;
-				C_FLAG=0;
-			end
+			`ALU_OP_SHIFT_LEFT: begin C_FLAG=(A&16'h8000)==16'h8000;OUT=A<<B; end
 		endcase
 	end else begin
 		case (op)
@@ -52,10 +49,7 @@ always @ ( * ) begin
 			`ALU_OP_AND: begin C_FLAG=0;OUT=A&B; end
 			`ALU_OP_OR:  begin C_FLAG=0;OUT=A|B; end
 			`ALU_OP_XOR: begin C_FLAG=0;OUT=A^B; end
-			default:begin
-				OUT=0;
-				C_FLAG=0;
-			end
+			`ALU_OP_SHIFT_LEFT: begin C_FLAG=(A&16'h80)==16'h80;OUT=A<<B; end
 		endcase
 	end
 end
diff --git a/system/alu_header.v b/system/alu_header.v
index 07e4fcb..83b35c7 100644
--- a/system/alu_header.v
+++ b/system/alu_header.v
@@ -25,3 +25,4 @@
 `define ALU_OP_XOR		3'b100
 `define ALU_OP_ADD_SIGNED_B	3'b101
 `define ALU_OP_SUB_REVERSE	3'b110
+`define ALU_OP_SHIFT_LEFT	3'b111
diff --git a/system/boot_code.asm b/system/boot_code.asm
index 94a21f1..5c153bf 100644
--- a/system/boot_code.asm
+++ b/system/boot_code.asm
@@ -1,3 +1,8 @@
+.ORG 0x84 /* INT 21 */
+DW 0xFFFF /*Code Segment*/
+DW 0x014c /*Program Counter*/
+
+.ORG 0x0100
 start:
 MOV SP,#STACK
 MOV AX,#0x0000
@@ -37,3 +42,7 @@ RET
 
  .BLKB 10
 STACK:
+
+.ORG 0xFFF0
+MOV AX,#0x0100
+JMP AX
diff --git a/system/decoder.v b/system/decoder.v
index 6ec3bf6..1b2dfb1 100644
--- a/system/decoder.v
+++ b/system/decoder.v
@@ -51,6 +51,7 @@ module decoder(
 	,output reg [2:0]ALU_1OP
 	,output reg [`UCODE_ADDR_BITS-1:0] seq_addr_entry, input wire SIMPLE_MICRO, input wire [`UCODE_ADDR_BITS-1:0] seq_addr_input
 	,output reg [2:0]instruction_size
+	,output reg memio_address_select
 );
 // verilator lint_on UNUSEDSIGNAL
 
@@ -109,6 +110,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				reg_read_port2_addr={Wbit,3'b000};
 				reg_write_addr={Wbit,3'b000};
 				ALU_1OP=`ALU_OP_ADD;
+				memio_address_select=0;
 				if(Wbit)
 					next_state=`PROC_DE_LOAD_16_PARAM;
 				else
@@ -135,6 +137,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 					in_alu1_sel2=2'b00;
 				end
 				OUT_MOD=IN_MOD;
+				memio_address_select=0;
 				case({Sbit,Wbit})
 					2'b00,2'b11:begin
 						next_state=`PROC_DE_LOAD_8_PARAM;
@@ -180,6 +183,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				in_alu1_sel1=2'b00;
 				OUT_MOD=3'b100;
 				ALU_1OP=`ALU_OP_SUB;
+				memio_address_select=0;
 				if(IN_MOD==3'b011)begin
 					/*compare register with param*/
 					in_alu1_sel2=2'b01;
@@ -209,6 +213,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				ALU_1OP=`ALU_OP_ADD;
 				next_state=`PROC_EX_STATE_ENTRY;
 				`normal_instruction;
+				memio_address_select=0;
 			end
 			11'b1011_1???_??? : begin
 				/*MOV - Move Immediate word to register*/
@@ -224,6 +229,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				PARAM2=0;
 				next_state=`PROC_DE_LOAD_16_PARAM;
 				`normal_instruction;
+				memio_address_select=0;
 			end
 			11'b1000_10??_??? : begin
 				/*                      MOV - Reg/Mem to/from register                        */
@@ -268,6 +274,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				ALU_1OP=`ALU_OP_ADD;
 
 				`normal_instruction;
+				memio_address_select=0;
 			end
 			11'b0100_????_???:begin//DEC
 				/* DEC - Decrement Register */
@@ -290,6 +297,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 					ALU_1OP=`ALU_OP_SUB;
 				next_state=`PROC_EX_STATE_ENTRY;
 				`normal_instruction;
+				memio_address_select=0;
 			end
 			11'b1111_111?_00? : begin
 				/*                          INC - Register/Memory                            */
@@ -316,6 +324,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				else
 					next_state=`PROC_MEMIO_READ;
 				`normal_instruction;
+				memio_address_select=0;
 			end
 			11'b1111_0100_??? : begin
 				/*     HLT - Halt     */
@@ -327,7 +336,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				ERROR<=0;
 				seq_addr_entry<=`UCODE_NO_INSTRUCTION;
 				next_state=`PROC_HALT_STATE;
-
+				memio_address_select=0;
 			end
 			11'b0011_110?_??? : begin
 				/*         CMP - Compare Immediate with accumulator        */
@@ -355,6 +364,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 					next_state=`PROC_EX_STATE_ENTRY;
 				end
 				`normal_instruction;
+				memio_address_select=0;
 			end
 			11'b0111_????_???:begin
 				/*     Conditional relative jumps       */
@@ -408,6 +418,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 					end
 				endcase
 				`normal_instruction;
+				memio_address_select=0;
 			end
 			11'b1110_1011_???:begin
 				/* JMP - Unconditional jump direct within segment (short) */
@@ -422,18 +433,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				OUT_MOD=3'b101;
 				next_state=`PROC_EX_STATE_ENTRY;
 				`normal_instruction;
-			end
-			11'b1100_1101_???:begin
-				/*    INT - execute interrupt handler   */
-				/* 1 1 0 0  1 1 0 1 |       DATA       |*/
-				instruction_size=2;
-				opcode_size=0;
-				/* Emulate MS-DOS print routines */
-				if(CIR[7:0]==8'h21 && register_file.registers[0][15:8]==8'h02)begin
-					$write("%s" ,register_file.registers[2][7:0]); /*TODO:Could trigger erroneously while CIR is not final*/
-				end
-				next_state=`PROC_IF_STATE_ENTRY;
-				`normal_instruction;
+				memio_address_select=0;
 			end
 			11'b1110_1000_???:begin
 				/*            CALL - Direct call within segment            */
@@ -446,6 +446,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				Sbit=1;
 				PARAM2=2; //subtract from sp
 				seq_addr_entry<=`UCODE_CALL_ENTRY;
+				memio_address_select=0;
 			end
 			11'b1100_0011_???:begin
 				/*  RET - Return from call within segment */
@@ -458,6 +459,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				Sbit=0;
 				PARAM1=2;
 				seq_addr_entry<=`UCODE_RET_ENTRY;
+				memio_address_select=0;
 			end
 			11'b1010_101?_???:begin
 				/*  STOS - Write byte/word to [DI] and increment accordingly */
@@ -469,6 +471,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				RM=3'b101;
 				seq_addr_entry<=`UCODE_STOS_ENTRY;
 				PARAM2=(Wbit==1)?2:1;
+				memio_address_select=0;
 			end
 			11'b0101_0???_???:begin
 				/*  PUSH -  SP-=2; [SP]=REG   */
@@ -480,6 +483,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				PARAM2=2;
 				reg_read_port2_addr={1'b1,CIR[10:8]};
 				seq_addr_entry<=`UCODE_PUSH_ENTRY;
+				memio_address_select=0;
 			end
 			11'b1111_011?_000:begin
 				/*                                     TEST - Bitwise AND affecting only flags                                     */
@@ -508,6 +512,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				endcase
 				OUT_MOD=3'b100;/*NULL*/
 				`normal_instruction;
+				memio_address_select=0;
 			end
 			11'b0101_1???_???:begin
 				/*  POP - REG=[SP]; SP+=2   */
@@ -519,6 +524,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				PARAM1=2;
 				reg_write_addr={1'b1,CIR[10:8]};
 				seq_addr_entry<=`UCODE_POP_ENTRY;
+				memio_address_select=0;
 			end
 			11'b1111_1111_100:begin
 				/*            JMP - Unconditional indirect within segment jump               */
@@ -540,6 +546,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				ALU_1OP=`ALU_OP_ADD;
 				OUT_MOD=3'b101;
 				`normal_instruction;
+				memio_address_select=0;
 			end
 			11'b1100_011?_000:begin
 				/*                                MOV - Move immediate to register/memory                                          */
@@ -560,6 +567,31 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				IN_MOD=3'b011;
 				RM=CIR[2:0];
 				`normal_instruction;
+				memio_address_select=0;
+			end
+			11'b1100_1101_???:begin
+				/*    INT - execute interrupt handler   */
+				/* 1 1 0 0  1 1 0 1 |       DATA       |*/
+				// [skiped] 1) push flags
+				// [skiped] 2) clear trap and interrupt enable flag
+				// [skiped] 3) push CS
+				// [skiped] 4) fetch CS from interrupt table
+				// 5) push ProgCount
+				// 6) fetch ProgCount from interrupt table
+				instruction_size=2;
+				opcode_size=0;
+				Wbit=1;
+				Sbit=0;
+				PARAM2=2;
+				seq_addr_entry<=`UCODE_INT_ENTRY;
+				memio_address_select=0;
+				///* Emulate MS-DOS print routines */
+				//if(CIR[7:0]==8'h21 && register_file.registers[0][15:8]==8'h02)begin
+				//	$write("%s" ,register_file.registers[2][7:0]); /*TODO:Could trigger erroneously while CIR is not final*/
+				//end
+				//next_state=`PROC_IF_STATE_ENTRY;
+				//`normal_instruction;
+				//memio_address_select=0;
 			end
 			default:begin
 				`invalid_instruction
@@ -570,20 +602,22 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 		//Sbit, Wbit, opcode_size and the others are still latched
 		//from when we ordered the switch to microcode
 		seq_addr_entry <= ucode_data[`UCODE_ADDR_BITS-1:0];
-		case(ucode_data[7:6])
-			2'b00: next_state=`PROC_EX_STATE_ENTRY;
-			2'b01: next_state=`PROC_DE_LOAD_16_PARAM;
-			2'b10: next_state=`PROC_DE_LOAD_8_PARAM;
-			2'b11: next_state=`PROC_MEMIO_READ;
+		case(ucode_data[8:6])
+			3'b000: next_state=`PROC_EX_STATE_ENTRY;
+			3'b001: next_state=`PROC_DE_LOAD_16_PARAM;
+			3'b010: next_state=`PROC_DE_LOAD_8_PARAM;
+			3'b011: next_state=`PROC_MEMIO_READ;
+			3'b100: next_state=`PROC_MEMIO_READ_SETADDR;
+			default: begin end /*impossible*/
 		endcase
-		if(ucode_data[35:35]==0)
-			reg_write_addr=ucode_data[11:8 ];
-		in_alu1_sel1  =ucode_data[13:12];
-		in_alu1_sel2  =ucode_data[15:14];
-		OUT_MOD       =ucode_data[18:16];
+		if(ucode_data[36:36]==0)
+			reg_write_addr=ucode_data[12:9 ];
+		in_alu1_sel1  =ucode_data[14:13];
+		in_alu1_sel2  =ucode_data[16:15];
+		OUT_MOD       =ucode_data[19:17];
 		/*1:1 map essentially but I want to keep the spec for these bits separate
 		* from the alu op select bits*/
-		case(ucode_data[21:19])
+		case(ucode_data[22:20])
 			3'b000: ALU_1OP=`ALU_OP_ADD;
 			3'b001: ALU_1OP=`ALU_OP_SUB;
 			3'b010: ALU_1OP=`ALU_OP_AND;
@@ -591,15 +625,17 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 			3'b100: ALU_1OP=`ALU_OP_XOR;
 			3'b101: ALU_1OP=`ALU_OP_ADD_SIGNED_B;
 			3'b110: ALU_1OP=`ALU_OP_SUB_REVERSE;
+			3'b111: ALU_1OP=`ALU_OP_SHIFT_LEFT;
 			default: begin end
 		endcase
-		if(ucode_data[33:33]==0)
-			reg_read_port1_addr=ucode_data[25:22];
-		IN_MOD=ucode_data[28:26];
 		if(ucode_data[34:34]==0)
-			reg_read_port2_addr=ucode_data[32:29];
-		if(ucode_data[37:37]==1)
-			Wbit=ucode_data[36:36];
+			reg_read_port1_addr=ucode_data[26:23];
+		IN_MOD=ucode_data[29:27];
+		if(ucode_data[35:35]==0)
+			reg_read_port2_addr=ucode_data[33:30];
+		if(ucode_data[38:38]==1)
+			Wbit=ucode_data[37:37];
+		memio_address_select=ucode_data[39:39];
 	end
 end
 `undef invalid_instruction
diff --git a/system/processor.v b/system/processor.v
index 9f158a5..6cd9237 100644
--- a/system/processor.v
+++ b/system/processor.v
@@ -57,6 +57,7 @@ wire [2:0] DE_instruction_size;
 reg instruction_size_init;
 wire [2:0] instruction_size;
 assign instruction_size = instruction_size_init ? 3'b010 : DE_instruction_size;
+wire memio_address_select;
 
 decoder decoder(
 	.CIR(CIR),
@@ -76,7 +77,8 @@ decoder decoder(
 	.seq_addr_entry(ucode_seq_addr_entry),
 	.SIMPLE_MICRO(SIMPLE_MICRO),
 	.seq_addr_input(ucode_seq_addr),
-	.instruction_size(DE_instruction_size)
+	.instruction_size(DE_instruction_size),
+	.memio_address_select(memio_address_select)
 );
 
 assign Wbit=INSTRUCTION_INFO[2:2];
@@ -194,7 +196,7 @@ always @(posedge clock) begin
 	case(state)
 		`PROC_RESET:begin
 			ucode_seq_addr <= `UCODE_NO_INSTRUCTION;
-			ProgCount <= 0;//TODO: Reset Vector
+			ProgCount <= 'hFFF0;//TODO: Implement Segmentation and set to zero
 			HALT <= 0;
 			ERROR <= 0;
 			IOMEM <= 0;
@@ -438,7 +440,10 @@ always @(posedge clock) begin
 			endcase
 		end
 		`PROC_MEMIO_READ_SETADDR:begin
-			external_address_bus <= {4'b0,reg_read_port1_data[15:0]};
+			if(memio_address_select==0)
+				external_address_bus <= {4'b0,reg_read_port1_data[15:0]};
+			else
+				external_address_bus <= {4'b0,ALU_1O};
 			state <= reg_read_port1_data[0:0]?`PROC_MEMIO_GET_UNALIGNED_DATA:`PROC_MEMIO_GET_ALIGNED_DATA;
 		end
 		`PROC_MEMIO_GET_ALIGNED_DATA:begin
@@ -531,6 +536,13 @@ always @(posedge clock) begin
 					reg_read_port1_addr <= 4'b1100;
 					state <= `PROC_MEMIO_WRITE;
 				end
+				3'b111:begin /* Write to PRAM1 (for microcode calculations) */
+					PARAM1 <= ALU_1O;
+					if (ucode_seq_addr==`UCODE_NO_INSTRUCTION)
+						state <= `PROC_IF_STATE_ENTRY;
+					else
+						state <= `PROC_NEXT_MICROCODE;
+				end
 				default:begin
 					`invalid_instruction
 				end
diff --git a/system/system.v b/system/system.v
index 4292239..2c09abb 100644
--- a/system/system.v
+++ b/system/system.v
@@ -3,6 +3,7 @@
 
 module system ( input clock,input reset, output [19:0]address_bus, inout [15:0]data_bus,output BHE, output rd, output wr, output IOMEM, output HALT, output ERROR);
 processor p(clock,reset,address_bus,data_bus,rd,wr,BHE,IOMEM,HALT,ERROR);
+
 doublemem sysmem(address_bus,data_bus,rd,wr,BHE,IOMEM);
 
 string waveform_name;
diff --git a/system/ucode.txt b/system/ucode.txt
index d5e1cdc..d8f6b3e 100644
--- a/system/ucode.txt
+++ b/system/ucode.txt
@@ -17,6 +17,8 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+//mas: MemIo Address Select
+//        0: register file output  1: alu output
 //wbo: Wbit overwrite, {VALUE,ENABLE}. ex 11 would force one, 10 wouldn't do anything
 //
 //krs: Keep registers, selects weather the register port 1 and/or 2
@@ -38,8 +40,9 @@
 //    100:ALU_OP_XOR
 //    101:ALU_OP_ADD_SIGNED_B
 //    110:ALU_OP_SUB_REVERSE
+//    111:ALU_OP_SHIFT_LEFT
 //
-//a1o: OUT_MOD. Handled in `PROC_EX_STATE_EXIT
+//a1o: OUT_MOD. Handled in `PROC_EX_STATE_ENTRY
 //
 //a12: In ALU 1 sel 2
 //
@@ -48,38 +51,49 @@
 //rwa: Register Write Address
 //
 //nxs: Next State
-//     00: PROC_EX_STATE_ENTRY
-//     01: PROC_DE_LOAD_16_PARAM
-//     10: PROC_DE_LOAD_8_PARAM
-//     11: PROC_MEMIO_READ
+//    000: PROC_EX_STATE_ENTRY
+//    001: PROC_DE_LOAD_16_PARAM
+//    010: PROC_DE_LOAD_8_PARAM
+//    011: PROC_MEMIO_READ
+//    100: PROC_MEMIO_READ_SETADDR (used when addressing based on ALU_OUT
 //
 //Nxt M: Next microcode address
 
-@000 _00_000_0000_000_0000_000_000__00__00_0000__00_000000
 
-//   36  34  32   28  25   21  18  15  13  11   7   5    0
-// CALL
-//   wbo|krs|rr2 |imd|rr1 |a1f|a1o|a12|a11|rwa |nxs|Nxt M |
-@001 _00_000_0000_011_1100_001_011__00__01_1100__01_000010 // ALU_1: SP           ALU_2: PARAM2 (2) ALU_OP:SUB  ALU_out: SP   (also fetch the opcode argument to PARAM1)
-@002 _00_000_0000_011_xxxx_000_110__10__11_xxxx__00_000011 // ALU_1: 0            ALU_2: PC         ALU_OP:ADD  ALU_out: [SP]
-@003 _00_000_0000_011_xxxx_000_101__10__00_xxxx__00_000000 // ALU_1: PARAM1 (arg) ALU_2: PC         ALU_OP:ADD  ALU_out: PC
-
-// RET
-//   wbo|krs|rr2 |imd|rr1 |a1f|a1o|a12|a11|rwa |nxs|Nxt M |
-@004 _00_000_0000_110_xxxx_000_101__00__11_xxxx__11_000101 // ALU_1: 0           ALU_2: PARAM2 ([SP]) ALU_OP:ADD  ALU_out: PC (also read [SP] to PARAM2)
-@005 _00_000_1100_011_0000_000_011__01__00_1100__00_000000 // ALU_1: PARAM1 (2)  ALU_2: SP            ALU_OP:ADD  ALU_out: SP
-
-// STOS
-//   wbo|krs|rr2 |imd|rr1 |a1f|a1o|a12|a11|rwa |nxs|Nxt M |
-@006 _00_000_1000_011_xxxx_000_000__01__11_xxxx__00_000111 // ALU_1: 0   ALU_2: AX           ALU_OP:ADD  ALU_out: [DI]
-@007 _11_000_xxxx_011_1111_000_011__00__01_1111__00_000000 // ALU_1: DI  ALU_2: PARAM2 (2)   ALU_OP:ADD  ALU_OUT: DI
-
-// PUSH
-//   wbo|krs|rr2 |imd|rr1 |a1f|a1o|a12|a11|rwa |nxs|Nxt M |
-@008 _00_010_0000_011_1100_001_011__00__01_1100__00_001001 // ALU_1: SP  ALU_2: PARAM2 (2) ALU_OP:SUB  ALU_out: SP   (also fetch the opcode argument to PARAM1)
-@009 _00_010_0000_011_xxxx_000_110__01__11_xxxx__00_000000 // ALU_1: 0   ALU_2: REG        ALU_OP:ADD  ALU_out: [SP]
+//   39  38  36  33   29  26   22  19  16  14  12   8   5    0
+// INT
+//   mas|wbo|krs|rr2 |imd|rr1 |a1f|a1o|a12|a11|rwa |nxs|Nxt M |
+@00c __0__00_000_0000_011_1100_001_011__00__01_1100_010_001101 // ALU_1: SP           ALU_2: PARAM2 (2) ALU_OP:SUB  ALU_out: SP   (also fetch the opcode argument to PARAM1)
+@00d __0__00_000_0000_011_xxxx_000_110__10__11_xxxx_000_001110 // ALU_1: 0            ALU_2: PC         ALU_OP:ADD  ALU_out: [SP]
+/* We read the parameter and get the address to jump on ALU_OUT */
+@00e __0__00_000_xxxx_011_xxxx_111_111__00__00_xxxx_000_001111 // ALU_1: PARAM1 (arg)                 ALU_2: PARAM2 (2)       ALU_OP:SHIFT ALU_out: PARAM1
+@00f __1__00_000_xxxx_011_xxxx_000_100__00__00_xxxx_100_010000 // ALU_1: PARAM1 (base int table addr) ALU_2: PARAM2 (2)       ALU_OP:ADD ALU_out: NULL
+@010 __0__00_000_xxxx_011_xxxx_000_101__00__11_xxxx_000_000000 // ALU_1: 0            ALU_2: PARAM2 (address) ALU_OP:SHIFT ALU_out: PC
 
 // POP
-//   wbo|krs|rr2 |imd|rr1 |a1f|a1o|a12|a11|rwa |nxs|Nxt M |
-@00a _00_100_0000_110_xxxx_011_011__00__11_xxxx__11_001011 // ALU_1: 0           ALU_2: PARAM2 ([SP])    ALU_OP:ADD   ALU_out: REG
-@00b _00_000_1100_011_0000_000_011__01__00_1100__00_000000 // ALU_1: PARAM1 (2)  ALU_2: SP               ALU_OP:ADD   ALU_out: SP 
+//   mas|wbo|krs|rr2 |imd|rr1 |a1f|a1o|a12|a11|rwa |nxs|Nxt M |
+@00a __0__00_100_0000_110_xxxx_011_011__00__11_xxxx_011_001011 // ALU_1: 0           ALU_2: PARAM2 ([SP])    ALU_OP:ADD   ALU_out: REG
+@00b __0__00_000_1100_011_0000_000_011__01__00_1100_000_000000 // ALU_1: PARAM1 (2)  ALU_2: SP               ALU_OP:ADD   ALU_out: SP 
+
+// PUSH
+//   mas|wbo|krs|rr2 |imd|rr1 |a1f|a1o|a12|a11|rwa |nxs|Nxt M |
+@008 __0__00_010_0000_011_1100_001_011__00__01_1100_000_001001 // ALU_1: SP  ALU_2: PARAM2 (2) ALU_OP:SUB  ALU_out: SP   (also fetch the opcode argument to PARAM1)
+@009 __0__00_010_0000_011_xxxx_000_110__01__11_xxxx_000_000000 // ALU_1: 0   ALU_2: REG        ALU_OP:ADD  ALU_out: [SP]
+
+// STOS
+//   mas|wbo|krs|rr2 |imd|rr1 |a1f|a1o|a12|a11|rwa |nxs|Nxt M |
+@006 __0__00_000_1000_011_xxxx_000_000__01__11_xxxx_000_000111 // ALU_1: 0   ALU_2: AX           ALU_OP:ADD  ALU_out: [DI]
+@007 __0__11_000_xxxx_011_1111_000_011__00__01_1111_000_000000 // ALU_1: DI  ALU_2: PARAM2 (2)   ALU_OP:ADD  ALU_OUT: DI
+
+// RET
+//   mas|wbo|krs|rr2 |imd|rr1 |a1f|a1o|a12|a11|rwa |nxs|Nxt M |
+@004 __0__00_000_0000_110_xxxx_000_101__00__11_xxxx_011_000101 // ALU_1: 0           ALU_2: PARAM2 ([SP]) ALU_OP:ADD  ALU_out: PC (also read [SP] to PARAM2)
+@005 __0__00_000_1100_011_0000_000_011__01__00_1100_000_000000 // ALU_1: PARAM1 (2)  ALU_2: SP            ALU_OP:ADD  ALU_out: SP
+
+// CALL
+//   mas|wbo|krs|rr2 |imd|rr1 |a1f|a1o|a12|a11|rwa |nxs|Nxt M |
+@001 __0__00_000_0000_011_1100_001_011__00__01_1100_001_000010 // ALU_1: SP           ALU_2: PARAM2 (2) ALU_OP:SUB  ALU_out: SP   (also fetch the opcode argument to PARAM1)
+@002 __0__00_000_0000_011_xxxx_000_110__10__11_xxxx_000_000011 // ALU_1: 0            ALU_2: PC         ALU_OP:ADD  ALU_out: [SP]
+@003 __0__00_000_0000_011_xxxx_000_101__10__00_xxxx_000_000000 // ALU_1: PARAM1 (arg) ALU_2: PC         ALU_OP:ADD  ALU_out: PC
+
+@000 __0__00_000_0000_000_0000_000_000__00__00_0000_000_000000
diff --git a/system/ucode_header.v b/system/ucode_header.v
index 3ac1a28..d508aaa 100644
--- a/system/ucode_header.v
+++ b/system/ucode_header.v
@@ -17,14 +17,15 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-`define UCODE_SIZE 12
-`define UCODE_DATA_BITS 38
+`define UCODE_SIZE 17
+`define UCODE_DATA_BITS 40
 `define UCODE_ADDR_BITS $clog2(`UCODE_SIZE)
 
 /* DEFINE ADDRESSES IN THE MICROCODE */
-`define UCODE_NO_INSTRUCTION	4'b0000
-`define UCODE_CALL_ENTRY	4'b0001
-`define UCODE_RET_ENTRY		4'b0100
-`define UCODE_STOS_ENTRY	4'b0110
-`define UCODE_PUSH_ENTRY        4'b1000
-`define UCODE_POP_ENTRY		4'b1010
+`define UCODE_NO_INSTRUCTION	5'b00000
+`define UCODE_CALL_ENTRY	5'b00001
+`define UCODE_RET_ENTRY		5'b00100
+`define UCODE_STOS_ENTRY	5'b00110
+`define UCODE_PUSH_ENTRY        5'b01000
+`define UCODE_POP_ENTRY		5'b01010
+`define UCODE_INT_ENTRY		5'b01100