diff --git a/libvm/as/as.c b/libvm/as/as.c
index 613dfc5..f6db6fa 100644
--- a/libvm/as/as.c
+++ b/libvm/as/as.c
@@ -57,17 +57,23 @@ int listSymbols = 0;
 // current token
 int tok;
 
+void apply_modifier(instruction_t *i, const char *mod);
+
 void apply_modifiers(instruction_t *i)
 {
 	while(tok == TOK_MOD)
 	{
-		printf("modifier, ");
+		char *s = yytext + 1;
+		int len = strlen(s);
+		s[len - 1] = 0;
+		apply_modifier(i, s);
 		tok = yylex();
 	}
 }
 
+
 // line format:
-// TOK_LABEL? TOK_MOD* TOK_MNEMONIC TOK_MOD* ()? TOK_MOD* TOK_NEWLINE
+// TOK_LABEL? TOK_MOD* TOK_MNEMONIC TOK_MOD* (TOK_INT|TOK_HEX|TOK_CHAR|TOK_REF)? TOK_MOD* TOK_NEWLINE
 void assemble()
 {
 	uint32_t index = 0;
@@ -156,7 +162,6 @@ void assemble()
 			// Increase command index by one
 			index += 1;
 		}
-		printf("NEXT\n");
 	}
 	
 	if(listSymbols)
@@ -168,7 +173,7 @@ void assemble()
 		}
 	}
 	
-	printf("Patches:\n");
+	// printf("Patches:\n");
 	for(llist_t *it = patches; it != NULL; it = it->next)
 	{
 		uint32_t target = list_find(&labels, it->name);
@@ -177,7 +182,7 @@ void assemble()
 		fseek(output, sizeof(instruction_t) * it->value + 4, SEEK_SET);
 		fwrite(&target, 1, sizeof(uint32_t), output);
 		
-		printf("%d -> %d (%s)\n", it->value, target, it->name);
+		// printf("%d -> %d (%s)\n", it->value, target, it->name);
 	}
 }
 
@@ -238,4 +243,98 @@ int main(int argc, char **argv)
 	}
 	
 	return 0;
+}
+
+void apply_modifier(instruction_t *i, const char *mod)
+{
+	// printf("[%s]\n", mod);
+	if(strncmp("ci:", mod, 3) == 0)
+	{
+		i->cmdinfo = atoi(mod + 3);
+		return;
+	}
+
+	if(strncmp("cmd:", mod, 4) == 0)
+	{
+		fprintf(stderr, "Command specification %s not supported yet.\n");
+		exit(1);
+	}
+	
+	if(strcmp("f:yes", mod) == 0)
+	{
+		i->flags = 1;
+	}
+	else if(strcmp("f:no", mod) == 0)
+	{
+		i->flags = 0;
+	}
+	else if(strcmp("r:discard", mod) == 0)
+	{
+		i->output = VM_OUTPUT_DISCARD;
+	}
+	else if(strcmp("r:push", mod) == 0)
+	{
+		i->output = VM_OUTPUT_PUSH;
+	}
+	else if(strcmp("r:jump", mod) == 0)
+	{
+		i->output = VM_OUTPUT_JUMP;
+	}
+	else if(strcmp("r:jumpr", mod) == 0)
+	{
+		i->output = VM_OUTPUT_JUMPR;
+	}
+	else if(strcmp("i0:zero", mod) == 0)
+	{
+		i->input0 = VM_INPUT_ZERO;
+	}
+	else if(strcmp("i0:pop", mod) == 0)
+	{
+		i->input0 = VM_INPUT_POP;
+	}
+	else if(strcmp("i0:peek", mod) == 0)
+	{
+		i->input0 = VM_INPUT_PEEK;
+	}
+	else if(strcmp("i0:arg", mod) == 0)
+	{
+		i->input0 = VM_INPUT_ARG;
+	}
+	else if(strcmp("i1:zero", mod) == 0)
+	{
+		i->input1 = VM_INPUT_ZERO;
+	}
+	else if(strcmp("i1:pop", mod) == 0)
+	{
+		i->input1 = VM_INPUT_POP;
+	}
+	else if(strcmp("ex(z)=x", mod) == 0)
+	{
+		i->execZ = VM_EXEC_X;
+	}
+	else if(strcmp("ex(z)=0", mod) == 0)
+	{
+		i->execZ = VM_EXEC_0;
+	}
+	else if(strcmp("ex(z)=1", mod) == 0)
+	{
+		i->execZ = VM_EXEC_1;
+	}
+	else if(strcmp("ex(n)=x", mod) == 0)
+	{
+		i->execN = VM_EXEC_X;
+	}
+	else if(strcmp("ex(n)=0", mod) == 0)
+	{
+		i->execN = VM_EXEC_0;
+	}
+	else if(strcmp("ex(n)=1", mod) == 0)
+	{
+		i->execN = VM_EXEC_1;
+	}
+	else
+	{
+		fprintf(stderr, "Unknown modifier: [%s]\n", mod);
+		exit(1);
+	}
 }
\ No newline at end of file
diff --git a/libvm/as/tokens.c b/libvm/as/tokens.c
index 3a576fb..7733dd3 100644
--- a/libvm/as/tokens.c
+++ b/libvm/as/tokens.c
@@ -385,11 +385,11 @@ struct yy_trans_info
 	flex_int32_t yy_verify;
 	flex_int32_t yy_nxt;
 	};
-static yyconst flex_int16_t yy_accept[28] =
+static yyconst flex_int16_t yy_accept[30] =
     {   0,
-        0,    0,   13,   11,    4,   10,   11,    3,    3,    1,
-       11,    5,   11,   11,    0,    3,    6,    0,    0,    1,
-        9,    5,    0,    8,    2,    7,    0
+        0,    0,   13,   11,    4,   10,   11,   11,    3,    3,
+        1,   11,    5,   11,   11,    0,    3,    3,    6,    0,
+        0,    1,    9,    5,    0,    8,    2,    7,    0
     } ;
 
 static yyconst YY_CHAR yy_ec[256] =
@@ -398,16 +398,16 @@ static yyconst YY_CHAR yy_ec[256] =
         1,    1,    1,    1,    1,    1,    1,    1,    1,    1,
         1,    1,    1,    1,    1,    1,    1,    1,    1,    1,
         1,    2,    1,    1,    1,    1,    1,    1,    4,    1,
-        1,    1,    1,    1,    1,    1,    1,    5,    6,    6,
-        6,    6,    6,    6,    6,    6,    6,    7,    8,    1,
-        1,    1,    1,    9,   10,   10,   10,   10,   10,   10,
-       11,   11,   11,   11,   11,   11,   11,   11,   11,   11,
-       11,   11,   11,   11,   11,   11,   11,   11,   11,   11,
-       12,    1,   13,    1,   14,    1,   10,   10,   10,   10,
+        1,    1,    1,    1,    5,    1,    1,    6,    7,    7,
+        7,    7,    7,    7,    7,    7,    7,    8,    9,    1,
+        1,    1,    1,   10,   11,   11,   11,   11,   11,   11,
+       12,   12,   12,   12,   12,   12,   12,   12,   12,   12,
+       12,   12,   12,   12,   12,   12,   12,   12,   12,   12,
+       13,    1,   14,    1,   15,    1,   11,   11,   11,   11,
 
-       10,   10,   11,   11,   11,   11,   11,   11,   11,   11,
-       11,   11,   11,   11,   11,   11,   11,   11,   11,   15,
-       11,   11,    1,    1,    1,    1,    1,    1,    1,    1,
+       11,   11,   12,   12,   12,   12,   12,   12,   12,   12,
+       12,   12,   12,   12,   12,   12,   12,   12,   12,   16,
+       12,   12,    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,    1,    1,
         1,    1,    1,    1,    1,    1,    1,    1,    1,    1,
@@ -424,50 +424,50 @@ static yyconst YY_CHAR yy_ec[256] =
         1,    1,    1,    1,    1
     } ;
 
-static yyconst YY_CHAR yy_meta[16] =
+static yyconst YY_CHAR yy_meta[17] =
     {   0,
-        1,    1,    2,    1,    3,    3,    1,    1,    1,    3,
-        3,    1,    4,    3,    3
+        1,    1,    2,    1,    1,    3,    3,    1,    1,    1,
+        3,    3,    1,    4,    3,    3
     } ;
 
-static yyconst flex_uint16_t yy_base[32] =
+static yyconst flex_uint16_t yy_base[34] =
     {   0,
-        0,    0,   31,   61,   61,   61,    0,   11,   15,    0,
-        0,   22,    0,   28,   20,    8,   61,    0,   39,    0,
-        0,    0,    7,   61,    0,   61,   61,   49,   53,   16,
-       57
+        0,    0,   38,   64,   64,   64,    0,   11,   13,   21,
+        0,    0,   24,    0,   30,   30,   16,   17,   64,    0,
+       41,    0,    0,    0,   13,   64,    0,   64,   64,   52,
+       56,   23,   60
     } ;
 
-static yyconst flex_int16_t yy_def[32] =
+static yyconst flex_int16_t yy_def[34] =
     {   0,
-       27,    1,   27,   27,   27,   27,   28,   27,    8,   29,
-       30,   27,   31,   12,   27,    8,   27,   14,   14,   29,
-       30,   12,   31,   27,   19,   27,    0,   27,   27,   27,
-       27
+       29,    1,   29,   29,   29,   29,   30,   29,   29,    9,
+       31,   32,   29,   33,   13,   29,   29,    9,   29,   15,
+       15,   31,   32,   13,   33,   29,   21,   29,    0,   29,
+       29,   29,   29
     } ;
 
-static yyconst flex_uint16_t yy_nxt[77] =
+static yyconst flex_uint16_t yy_nxt[81] =
     {   0,
-        4,    5,    6,    7,    8,    9,    4,   10,   11,   12,
-       12,   13,    4,   14,   12,   16,   16,   17,   21,   26,
-       18,   18,   18,   24,   18,   19,   18,   18,   17,   18,
-       27,   22,   22,   27,   27,   18,   22,   18,   18,   27,
-       27,   27,   18,   25,   25,   27,   27,   27,   25,   15,
-       27,   15,   15,   20,   27,   20,   20,   23,   23,   23,
-        3,   27,   27,   27,   27,   27,   27,   27,   27,   27,
-       27,   27,   27,   27,   27,   27
+        4,    5,    6,    7,    8,    9,   10,    4,   11,   12,
+       13,   13,   14,    4,   15,   13,   17,   17,   18,   18,
+       19,   17,   17,   20,   20,   23,   28,   20,   21,   20,
+       20,   19,   20,   26,   24,   24,   20,   29,   20,   24,
+       20,   20,   29,   29,   29,   20,   27,   27,   29,   29,
+       29,   27,   16,   29,   16,   16,   22,   29,   22,   22,
+       25,   25,   25,    3,   29,   29,   29,   29,   29,   29,
+       29,   29,   29,   29,   29,   29,   29,   29,   29,   29
     } ;
 
-static yyconst flex_int16_t yy_chk[77] =
+static yyconst flex_int16_t yy_chk[81] =
     {   0,
         1,    1,    1,    1,    1,    1,    1,    1,    1,    1,
-        1,    1,    1,    1,    1,    8,    8,    8,   30,   23,
-        8,    8,   16,   15,    8,    8,   12,   12,   12,    9,
-        3,   12,   12,    0,    0,   12,   12,   14,   14,    0,
-        0,    0,   14,   19,   19,    0,    0,    0,   19,   28,
-        0,   28,   28,   29,    0,   29,   29,   31,   31,   31,
-       27,   27,   27,   27,   27,   27,   27,   27,   27,   27,
-       27,   27,   27,   27,   27,   27
+        1,    1,    1,    1,    1,    1,    8,    8,    9,    9,
+        9,   17,   17,    9,    9,   32,   25,    9,    9,   13,
+       13,   13,   18,   16,   13,   13,   10,    3,   13,   13,
+       15,   15,    0,    0,    0,   15,   21,   21,    0,    0,
+        0,   21,   30,    0,   30,   30,   31,    0,   31,   31,
+       33,   33,   33,   29,   29,   29,   29,   29,   29,   29,
+       29,   29,   29,   29,   29,   29,   29,   29,   29,   29
     } ;
 
 static yy_state_type yy_last_accepting_state;
@@ -735,13 +735,13 @@ yy_match:
 			while ( yy_chk[yy_base[yy_current_state] + yy_c] != yy_current_state )
 				{
 				yy_current_state = (int) yy_def[yy_current_state];
-				if ( yy_current_state >= 28 )
+				if ( yy_current_state >= 30 )
 					yy_c = yy_meta[(unsigned int) yy_c];
 				}
 			yy_current_state = yy_nxt[yy_base[yy_current_state] + (unsigned int) yy_c];
 			++yy_cp;
 			}
-		while ( yy_base[yy_current_state] != 61 );
+		while ( yy_base[yy_current_state] != 64 );
 
 yy_find_action:
 		yy_act = yy_accept[yy_current_state];
@@ -1120,7 +1120,7 @@ static int yy_get_next_buffer (void)
 		while ( yy_chk[yy_base[yy_current_state] + yy_c] != yy_current_state )
 			{
 			yy_current_state = (int) yy_def[yy_current_state];
-			if ( yy_current_state >= 28 )
+			if ( yy_current_state >= 30 )
 				yy_c = yy_meta[(unsigned int) yy_c];
 			}
 		yy_current_state = yy_nxt[yy_base[yy_current_state] + (unsigned int) yy_c];
@@ -1148,11 +1148,11 @@ static int yy_get_next_buffer (void)
 	while ( yy_chk[yy_base[yy_current_state] + yy_c] != yy_current_state )
 		{
 		yy_current_state = (int) yy_def[yy_current_state];
-		if ( yy_current_state >= 28 )
+		if ( yy_current_state >= 30 )
 			yy_c = yy_meta[(unsigned int) yy_c];
 		}
 	yy_current_state = yy_nxt[yy_base[yy_current_state] + (unsigned int) yy_c];
-	yy_is_jam = (yy_current_state == 27);
+	yy_is_jam = (yy_current_state == 29);
 
 		return yy_is_jam ? 0 : yy_current_state;
 }
diff --git a/libvm/as/tokens.y b/libvm/as/tokens.y
index 0935dc3..c5d5a95 100644
--- a/libvm/as/tokens.y
+++ b/libvm/as/tokens.y
@@ -7,7 +7,7 @@ whitespace	[ \t]
 newline     [\n]
 digit				[0-9]
 hexdigit    [0-9a-fA-F]
-intnum			{digit}+
+intnum			-?{digit}+
 hexnum			"0x"{hexdigit}+
 mnemonic    [a-zA-Z]+
 labelname   [a-zA-Z0-9_]+