Added the OUT instruction to be able to properly address I/O and moved printing logic to a device on the I/O space. Also added IRET which is basically just a RET in this case

Makefile

@@ -23,9 +23,6 @@ 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
 

boot_code/brainfuck_compiled.asm

@@ -1,8 +1,20 @@
+.ORG 0x84           ; INT 21
+DW 0xFFFF           ; Code Segment
+DW PRINT_INT_HANDLE ; Program Counter
+
 org 0x100
 INCLUDE brainfuck_compiler_v1.asm
 
 prog:
 INCLUDE hello_9086.bf.asm
+
+PRINT_INT_HANDLE:
+push AX
+MOV AL,DL
+out byte #0xA5
+POP AX
+iret
+
 output_program:
 
 .ORG 0xFFF0

boot_code/brainfuck_interpreted.asm

@@ -1,6 +1,21 @@
+.ORG 0x84           ; INT 21
+DW 0xFFFF           ; Code Segment
+DW PRINT_INT_HANDLE ; Program Counter
+
 ORG 0x100
+mov sp,#STACK
 INCLUDE brainfuck_interpreter_v0.asm
 
+PRINT_INT_HANDLE:
+push AX
+MOV AL,DL
+out byte #0xA5
+POP AX
+iret
+
+ .BLKB 200
+STACK:
+
 prog:
 INCLUDE hello_9086.bf.asm
 

boot_code/brainfuck_mandelbrot.asm

@@ -1,6 +1,17 @@
+.ORG 0x84           ; INT 21
+DW 0xFFFF           ; Code Segment
+DW PRINT_INT_HANDLE ; Program Counter
+
 ORG 0x100
 INCLUDE brainfuck_compiler_v1.asm
 
+PRINT_INT_HANDLE:
+push AX
+MOV AL,DL
+out byte #0xA5
+POP AX
+iret
+
 prog:
 INCLUDE mandelbrot.bf.asm
 

gtkwave_savefile.gtkw

@@ -1,15 +1,15 @@
 [*]
 [*] GTKWave Analyzer v3.3.111 (w)1999-2020 BSI
-[*] Sat Mar  4 23:56:38 2023
+[*] Thu Mar  9 04:20:33 2023
 [*]
-[dumpfile] "/home/user/9086/boot_code/brainfuck_compiled.fst"
+[dumpfile] "/home/user/9086/system/boot_code.fst"
-[dumpfile_mtime] "Sat Mar  4 23:55:57 2023"
+[dumpfile_mtime] "Thu Mar  9 04:18:18 2023"
-[dumpfile_size] 464968
+[dumpfile_size] 8510
 [savefile] "/home/user/9086/gtkwave_savefile.gtkw"
-[timestart] 500000000
+[timestart] 198700000000
-[size] 1332 1017
+[size] 1236 1017
 [pos] -1 -1
-*-37.895050 40500000000 -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
+*-34.595051 280500000000 -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] TOP.
 [treeopen] TOP.system.
 [sst_width] 221
@@ -21,7 +21,7 @@ TOP.system.clock
 TOP.system.reset
 TOP.system.p.state[5:0]
 @22
-TOP.system.p.ucode_seq_addr[3:0]
+TOP.system.p.ucode_seq_addr[4:0]
 TOP.system.address_bus[19:0]
 TOP.system.data_bus[15:0]
 TOP.system.p.CIR[15:0]
@@ -30,13 +30,14 @@ TOP.system.p.PARAM2[15:0]
 @28
 TOP.system.p.read
 TOP.system.p.write
+@29
+TOP.system.IOMEM
 @22
 TOP.system.p.ALU_1A[15:0]
 TOP.system.p.ALU_1B[15:0]
 TOP.system.p.ALU_1O[15:0]
 @28
 TOP.system.p.ERROR
-@29
 TOP.system.p.HALT
 [pattern_trace] 1
 [pattern_trace] 0

system/alu.v

@@ -41,6 +41,7 @@ always @ ( * ) begin
 			`ALU_OP_SHIFT_LEFT: begin C_FLAG=(A&16'h8000)==16'h8000;OUT=A<<B; end
 		endcase
 	end else begin
+		OUT[15:8]=8'b0;
 		case (op)
 			`ALU_OP_ADD: {C_FLAG,OUT[7:0]}=A[7:0]+B[7:0];
 			`ALU_OP_ADD_SIGNED_B: {C_FLAG,OUT[7:0]}=A[7:0]+SIGNED_8B;

system/boot_code.asm

@@ -1,6 +1,6 @@
-.ORG 0x84 /* INT 21 */
+.ORG 0x84           ; INT 21
-DW 0xFFFF /*Code Segment*/
+DW 0xFFFF           ; Code Segment
-DW 0x014c /*Program Counter*/
+DW PRINT_INT_HANDLE ; Program Counter
 
 .ORG 0x0100
 start:
@@ -40,6 +40,13 @@ TEST_:
 ADD AX,#0xDEAD
 RET
 
+PRINT_INT_HANDLE:
+push AX
+MOV AL,DL
+out byte #0xA5
+POP AX
+iret
+
  .BLKB 10
 STACK:
 

system/decoder.v

@@ -52,6 +52,7 @@ module decoder(
 	,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
+	,output reg MEM_OR_IO
 );
 // verilator lint_on UNUSEDSIGNAL
 
@@ -107,6 +108,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				in_alu1_sel1=2'b00;
 				in_alu1_sel2=2'b01;
 				OUT_MOD=3'b011;
+				MEM_OR_IO=0;
 				reg_read_port2_addr={Wbit,3'b000};
 				reg_write_addr={Wbit,3'b000};
 				ALU_1OP=`ALU_OP_ADD;
@@ -137,6 +139,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 					in_alu1_sel2=2'b00;
 				end
 				OUT_MOD=IN_MOD;
+				MEM_OR_IO=0;
 				memio_address_select=0;
 				case({Sbit,Wbit})
 					2'b00,2'b11:begin
@@ -182,6 +185,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				endcase
 				in_alu1_sel1=2'b00;
 				OUT_MOD=3'b100;
+				MEM_OR_IO=0;
 				ALU_1OP=`ALU_OP_SUB;
 				memio_address_select=0;
 				if(IN_MOD==3'b011)begin
@@ -193,7 +197,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 					/*compare register indirect access
 					* with param */
 					in_alu1_sel2=2'b00;
-					next_state=`PROC_DE_LOAD_16_PARAM; /*will the call MEMIO_READ*/
+					next_state=`PROC_DE_LOAD_16_PARAM; /*will then call MEMIO_READ*/
 				end
 				`normal_instruction;
 			end
@@ -207,6 +211,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				in_alu1_sel1=2'b00;
 				in_alu1_sel2=2'b00;
 				OUT_MOD=3'b011;
+				MEM_OR_IO=0;
 				reg_write_addr={1'b0,CIR[10:8]};
 				PARAM1[7:0]=CIR[7:0];
 				PARAM2=0;
@@ -224,6 +229,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				in_alu1_sel1=2'b00;
 				in_alu1_sel2=2'b00;
 				OUT_MOD=3'b011;
+				MEM_OR_IO=0;
 				reg_write_addr={1'b1,CIR[10:8]};
 				ALU_1OP=`ALU_OP_ADD;
 				PARAM2=0;
@@ -240,6 +246,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				Wbit=CIR[8:8];
 				in_alu1_sel1=2'b00;
 				PARAM1=0;
+				MEM_OR_IO=0;
 				if(CIR[9:9] == 1)begin
 					/* Mem/Reg to reg */
 					IN_MOD={1'b0,CIR[7:6]};
@@ -287,6 +294,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				in_alu1_sel1=2'b01;
 				in_alu1_sel2=2'b00;
 				OUT_MOD=3'b011;
+				MEM_OR_IO=0;
 				IN_MOD=3'b011;
 				PARAM2=1;
 				reg_read_port1_addr={1'b1,CIR[10:8]};
@@ -313,6 +321,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				in_alu1_sel1=2'b00;/* number 1 */
 				PARAM1=1;
 				OUT_MOD=IN_MOD;
+				MEM_OR_IO=0;
 
 				/*in case IN_MOD=011 */
 				reg_read_port2_addr={1'b0,RM};
@@ -334,6 +343,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				IN_MOD=3'b011;
 				HALT<=1;
 				ERROR<=0;
+				MEM_OR_IO=0;
 				seq_addr_entry<=`UCODE_NO_INSTRUCTION;
 				next_state=`PROC_HALT_STATE;
 				memio_address_select=0;
@@ -357,6 +367,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				reg_read_port2_addr={Wbit,3'b000};
 				OUT_MOD=3'b100;
 				ALU_1OP=`ALU_OP_SUB;
+				MEM_OR_IO=0;
 				if(Wbit==1)
 					next_state=`PROC_DE_LOAD_16_PARAM;
 				else begin
@@ -382,6 +393,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				in_alu1_sel2=2'b00;
 				PARAM2={{8{CIR[7:7]}},CIR[7:0]};
 				ALU_1OP=`ALU_OP_ADD_SIGNED_B;
+				MEM_OR_IO=0;
 				OUT_MOD=3'b101;
 				case(CIR[11:9])
 					3'b000: begin
@@ -431,6 +443,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				PARAM2={{8{CIR[7:7]}},CIR[7:0]};
 				ALU_1OP=`ALU_OP_ADD_SIGNED_B;
 				OUT_MOD=3'b101;
+				MEM_OR_IO=0;
 				next_state=`PROC_EX_STATE_ENTRY;
 				`normal_instruction;
 				memio_address_select=0;
@@ -492,6 +505,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				Wbit=CIR[8:8];
 				IN_MOD={1'b0,CIR[7:6]};
 				RM={CIR[2:0]};
+				MEM_OR_IO=0;
 				if(Wbit==1)begin
 					instruction_size=4;
 					next_state=`PROC_DE_LOAD_16_PARAM;
@@ -534,6 +548,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				Wbit=1;
 				IN_MOD={1'b0,CIR[7:6]};
 				RM=CIR[2:0];
+				MEM_OR_IO=0;
 				in_alu1_sel1=2'b11;
 				if (IN_MOD==3'b011)begin
 					in_alu1_sel2=2'b01;
@@ -555,6 +570,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				opcode_size=1;
 				in_alu1_sel1=2'b00;
 				in_alu1_sel2=2'b11;
+				MEM_OR_IO=0;
 				if(Wbit==1)begin
 					instruction_size=4;
 					next_state=`PROC_DE_LOAD_16_PARAM;
@@ -585,13 +601,35 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 				PARAM2=2;
 				seq_addr_entry<=`UCODE_INT_ENTRY;
 				memio_address_select=0;
-				///* Emulate MS-DOS print routines */
+			end
-				//if(CIR[7:0]==8'h21 && register_file.registers[0][15:8]==8'h02)begin
+			11'b1110_011?_???:begin
-				//	$write("%s" ,register_file.registers[2][7:0]); /*TODO:Could trigger erroneously while CIR is not final*/
+				/*  OUT - write AL or AX to a defined output port */
-				//end
+				/*    | 1 1 1 0  0 1 1 W |     DATA 8       |     */
-				//next_state=`PROC_IF_STATE_ENTRY;
+				memio_address_select=1;
-				//`normal_instruction;
+				Wbit=CIR[8:8];
-				//memio_address_select=0;
+				opcode_size=0;
+				instruction_size=2;
+				in_alu1_sel1=2'b00;
+				in_alu1_sel2=2'b11;
+				reg_read_port1_addr={Wbit,3'b000};
+				next_state=`PROC_DE_LOAD_8_PARAM;
+				MEM_OR_IO=1;
+				PARAM1=0;
+				OUT_MOD={3'b000};
+				IN_MOD=3'b011;
+			end
+			11'b1100_1111_???:begin
+				/*  IRET - Return from interrupt  */
+				/*      | 1 1 0 0  1 1 1 1 |      */
+				// Sicne we only push one thing on the stack
+				// on INT we can just reuse the code from RET
+				instruction_size=1;
+				opcode_size=0;
+				Wbit=1;
+				Sbit=0;
+				PARAM1=2;
+				seq_addr_entry<=`UCODE_RET_ENTRY;
+				memio_address_select=0;
 			end
 			default:begin
 				`invalid_instruction
@@ -636,6 +674,7 @@ always @( CIR or SIMPLE_MICRO or seq_addr_input ) begin
 		if(ucode_data[38:38]==1)
 			Wbit=ucode_data[37:37];
 		memio_address_select=ucode_data[39:39];
+		MEM_OR_IO=0;
 	end
 end
 `undef invalid_instruction

system/memory.v

@@ -30,7 +30,7 @@ initial begin
 		$display("No boot code specified. Please add +BOOT_CODE=<path> to your vvp args");
 		$finish;
 	end
-	$readmemh(boot_code, memory,0,16383);
+	$readmemh(boot_code, memory,0,32767);
 end
 
 assign data[7:0] = !address[0:0] & !rd & !cs ? memory[address[16:1]][15:8]  : 8'hz;

system/processor.v

@@ -58,6 +58,7 @@ reg instruction_size_init;
 wire [2:0] instruction_size;
 assign instruction_size = instruction_size_init ? 3'b010 : DE_instruction_size;
 wire memio_address_select;
+wire MEM_OR_IO;
 
 decoder decoder(
 	.CIR(CIR),
@@ -78,7 +79,8 @@ decoder decoder(
 	.SIMPLE_MICRO(SIMPLE_MICRO),
 	.seq_addr_input(ucode_seq_addr),
 	.instruction_size(DE_instruction_size),
-	.memio_address_select(memio_address_select)
+	.memio_address_select(memio_address_select),
+	.MEM_OR_IO(MEM_OR_IO)
 );
 
 assign Wbit=INSTRUCTION_INFO[2:2];
@@ -199,7 +201,6 @@ always @(posedge clock) begin
 			ProgCount <= 'hFFF0;//TODO: Implement Segmentation and set to zero
 			HALT <= 0;
 			ERROR <= 0;
-			IOMEM <= 0;
 			SIMPLE_MICRO <= 0;
 			reg_write_we <= 1;
 			instruction_size_init <= 1;
@@ -222,6 +223,7 @@ always @(posedge clock) begin
 			`endif
 			BHE <= 0;
 			external_address_bus <= {4'b0,ProgCount};
+			IOMEM <= 0;
 			read <= 0;
 			write <= 1;
 			reg_write_we <= 1;
@@ -444,7 +446,7 @@ always @(posedge clock) begin
 				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;
+			state <= (memio_address_select?ALU_1O[0:0]:reg_read_port1_data[0:0])?`PROC_MEMIO_GET_UNALIGNED_DATA:`PROC_MEMIO_GET_ALIGNED_DATA;
 		end
 		`PROC_MEMIO_GET_ALIGNED_DATA:begin
 			PARAM2 <= (Wbit==1)? external_data_bus : {8'b0,external_data_bus[7:0]} ;
@@ -473,6 +475,9 @@ always @(posedge clock) begin
 				3'b000,
 					3'b001,
 					3'b010 : begin
+					if(memio_address_select==1)
+						state <= `PROC_MEMIO_WRITE;
+					else
 						case (RM) /* Duplicate code with write... */
 							3'b000:begin
 								/*[BX]+[SI]*/
@@ -549,17 +554,26 @@ always @(posedge clock) begin
 			endcase
 		end
 		`PROC_MEMIO_WRITE:begin
-			/* ADDRESS: reg_read_port1_data   DATA:ALU1_O */
+			/* if memio_address_select == 0  ADDRESS: reg_read_port1_data   DATA:ALU1_O */
+			/* if memio_address_select == 1  ADDRESS: ALU1_O                DATA: reg_read_port1_data */
 			`ifdef DEBUG_MEMORY_WRITES
 				$display("Writing at %04x , %04x",reg_read_port1_data,ALU_1O);
 			`endif
+			if(memio_address_select==0)
 				external_address_bus <= {4'b0,reg_read_port1_data[15:0]};
+			else
+				external_address_bus <= {4'b0,ALU_1O};
+
+			IOMEM <= MEM_OR_IO;
 			state <= (Wbit==0) ? `PROC_MEMIO_PUT_BYTE : (reg_read_port1_data[0:0]?`PROC_MEMIO_PUT_UNALIGNED_16BIT_DATA:`PROC_MEMIO_PUT_ALIGNED_16BIT_DATA) ;
 		end
 		`PROC_MEMIO_PUT_UNALIGNED_16BIT_DATA:begin
 			read <= 1;
 			BHE <= 0;
+			if(memio_address_select==0)
 				data_bus_output_register <= {ALU_1O[7:0],ALU_1O[15:8]};
+			else
+				data_bus_output_register <= {reg_read_port1_data[7:0],reg_read_port1_data[15:8]};
 			state <= `PROC_MEMIO_PUT_UNALIGNED_PREP_NEXT;
 		end
 		`PROC_MEMIO_PUT_UNALIGNED_PREP_NEXT:begin
@@ -580,11 +594,18 @@ always @(posedge clock) begin
 		`PROC_MEMIO_PUT_BYTE:begin
 			read <= 1;
 			state <= `PROC_MEMIO_WRITE_EXIT;
-			if(reg_read_port1_data[0:0]==0) begin
+			if((memio_address_select?ALU_1O[0:0]:reg_read_port1_data[0:0])==0) begin
 				BHE <= 1;
+				if(memio_address_select==0)
 					data_bus_output_register <= {8'b0,ALU_1O[7:0]};
+				else
+					data_bus_output_register <= {8'b0,reg_read_port1_data[7:0]};
 			end else begin
+				BHE <= 0;
+				if(memio_address_select==0)
 					data_bus_output_register <= {ALU_1O[7:0],8'b0};
+				else
+					data_bus_output_register <= {reg_read_port1_data[7:0],8'b0};
 			end
 		end
 		`PROC_MEMIO_WRITE_EXIT:begin

system/system.v

@@ -14,6 +14,14 @@ initial begin
 	end
 end
 
+always @(negedge wr) begin
+	if(IOMEM==1'b1 && address_bus[7:0]==8'hA5 )
+		$write("%s" ,data_bus[15:8]);
+	//if(CIR[7:0]==8'h21 && register_file.registers[0][15:8]==8'h02)begin
+	//	$write("%s" ,register_file.registers[2][7:0]);
+	//end
+end
+
 reg [1:0] finish;
 
 string memdump_name;