diff --git a/c-print-array/main.c b/c-print-array/main.c
index 023adca..e25b83f 100644
--- a/c-print-array/main.c
+++ b/c-print-array/main.c
@@ -7,10 +7,10 @@ static int i = 0;
 void _start(void)
 {
 	/* TODO: handle sp/fp init better -- separate crt0.S? */
-	asm ("law 03000");
-	asm ("dac 209");
-	asm ("law 04000");
-	asm ("dac 208");
+	asm volatile ("law 03000");
+	asm volatile ("dac 0131");
+	asm volatile ("law 04000");
+	asm volatile ("dac 0130");
 	
 	/* check with no iterators */
 	putc(x[0]);
@@ -23,19 +23,19 @@ void _start(void)
 
 	/* check with local iterator w/o func call */
 	for (int j = 0; j < 3; j++) {
-		asm ("lio %0" : : "r"(x[j]));
-		asm ("tyo");
+		asm volatile ("lio %0" : : "r"(x[j]) : "$io");
+		asm volatile ("tyo");
 	}
 
 	/* check with local iterator w/ func call */
 	for (int j = 0; j < 3; j++)
 		putc(x[j]);
 
-	asm ("hlt");
+	asm volatile ("hlt");
 	__builtin_unreachable();
 }
 
 static void putc(int c) {
-	asm ("lio %0" : : "r"(c));
-	asm ("tyo");
+	asm volatile ("lio %0" : : "r"(c) : "$io");
+	asm volatile ("tyo");
 }
diff --git a/c-print-fibonacci/main.c b/c-print-fibonacci/main.c
index 6cd2b4c..154e163 100644
--- a/c-print-fibonacci/main.c
+++ b/c-print-fibonacci/main.c
@@ -7,9 +7,9 @@ static int fib(int);
 void _start(void)
 {
 	asm volatile ("law 04000");
-	asm volatile ("dac 209");
+	asm volatile ("dac 0131");
 	asm volatile ("law 03000");
-	asm volatile ("dac 208");
+	asm volatile ("dac 0130");
 
 	int n;
 
@@ -24,7 +24,7 @@ void _start(void)
 
 static void putc(int c)
 {
-	asm volatile ("lio %0" : : "r"(c) : "io");
+	asm volatile ("lio %0" : : "r"(c) : "$io");
 	asm volatile ("tyo");
 }
 
diff --git a/c-print-for-loop/main.c b/c-print-for-loop/main.c
index 0f883f0..0730440 100644
--- a/c-print-for-loop/main.c
+++ b/c-print-for-loop/main.c
@@ -3,10 +3,10 @@ static int get_char(int);
 
 void _start(void)
 {
-	asm ("law 04000");
-	asm ("dac 209");
-	asm ("law 03000");
-	asm ("dac 208");
+	asm volatile ("law 04000");
+	asm volatile ("dac 0131");
+	asm volatile ("law 03000");
+	asm volatile ("dac 0130");
 
 	int c;
 
@@ -15,13 +15,13 @@ void _start(void)
 		putc(c);
 	}
 
-	asm ("hlt");
+	asm volatile ("hlt");
 	__builtin_unreachable();
 }
 
 static void putc(int c) {
-	asm ("lio %0" : : "r"(c));
-	asm ("tyo");
+	asm volatile ("lio %0" : : "r"(c) : "$io");
+	asm volatile ("tyo");
 }
 
 static int get_char(int c)
diff --git a/c-print-struct/main.c b/c-print-struct/main.c
index d87abd4..26ec73b 100644
--- a/c-print-struct/main.c
+++ b/c-print-struct/main.c
@@ -8,9 +8,10 @@ static struct {
 
 void _start(void)
 {
-	asm ("law 04000");
-	asm ("dac 209");
-	asm ("dac 208");
+	asm volatile ("law 04000");
+	asm volatile ("dac 0131");
+	asm volatile ("law 03000");
+	asm volatile ("dac 0130");
 
 	x.field1 = 027;
 	x.field2 = 030;
@@ -26,6 +27,6 @@ void _start(void)
 }
 
 static void putc(int c) {
-	asm ("lio %0" : : "r"(c));
-	asm ("tyo");
+	asm volatile ("lio %0" : : "r"(c) : "$io");
+	asm volatile ("tyo");
 }
diff --git a/c-print-x/main.c b/c-print-x/main.c
index 9c430ab..35c7801 100644
--- a/c-print-x/main.c
+++ b/c-print-x/main.c
@@ -6,18 +6,19 @@ int y;
 
 void _start(void)
 {
-	asm ("law 04000");
-	asm ("dac 209");
-	asm ("dac 208");
+	asm volatile ("law 04000");
+	asm volatile ("dac 0131");
+	asm volatile ("law 03000");
+	asm volatile ("dac 0130");
 
-	asm ("lio %0" : : "r"(x));
-	asm ("tyo");
+	asm volatile ("lio %0" : : "r"(x) : "$io");
+	asm volatile ("tyo");
 
 	y = 027;
-	asm ("lio %0" : : "r"(y));
-	asm ("tyo");
+	asm volatile ("lio %0" : : "r"(y) : "$io");
+	asm volatile ("tyo");
 
-	asm ("hlt");
+	asm volatile ("hlt");
 
 	__builtin_unreachable();
 }
diff --git a/c-test-arith/main.c b/c-test-arith/main.c
index e7bf177..8679e16 100644
--- a/c-test-arith/main.c
+++ b/c-test-arith/main.c
@@ -7,10 +7,10 @@ int z;
 void _start(void)
 {
 	/* TODO: handle sp/fp init better -- separate crt0.S? */
-	asm ("law 03000");
-	asm ("dac 209");
-	asm ("law 04000");
-	asm ("dac 208");
+	asm volatile ("law 03000");
+	asm volatile ("dac 0131");
+	asm volatile ("law 04000");
+	asm volatile ("dac 0130");
 
 	x = 21;
 	y = 37;
@@ -23,11 +23,11 @@ void _start(void)
 	if (z == 4)
 		putc(027);
 
-	asm ("hlt");
+	asm volatile ("hlt");
 	__builtin_unreachable();
 }
 
 static void putc(int c) {
-	asm ("lio %0" : : "r"(c));
-	asm ("tyo");
+	asm volatile ("lio %0" : : "r"(c) : "$io");
+	asm volatile ("tyo");
 }
diff --git a/c-test-comparison/main.c b/c-test-comparison/main.c
index f72170c..408c553 100644
--- a/c-test-comparison/main.c
+++ b/c-test-comparison/main.c
@@ -3,10 +3,10 @@ static void putc(int);
 void _start(void)
 {
 	/* TODO: handle sp/fp init better -- separate crt0.S? */
-	asm ("law 03000");
-	asm ("dac 209");
-	asm ("law 04000");
-	asm ("dac 208");
+	asm volatile ("law 03000");
+	asm volatile ("dac 0131");
+	asm volatile ("law 04000");
+	asm volatile ("dac 0130");
 	
 	int x = 30;
 	int y = 30;
@@ -44,11 +44,11 @@ void _start(void)
 	if (x > y)
 		putc(071); // i
 
-	asm ("hlt");
+	asm volatile ("hlt");
 	__builtin_unreachable();
 }
 
 static void putc(int c) {
-	asm ("lio %0" : : "r"(c));
-	asm ("tyo");
+	asm volatile ("lio %0" : : "r"(c) : "$io");
+	asm volatile ("tyo");
 }
diff --git a/c-test-recursion/main.c b/c-test-recursion/main.c
index 73ab9ab..35ec738 100644
--- a/c-test-recursion/main.c
+++ b/c-test-recursion/main.c
@@ -5,20 +5,20 @@ static void foo(int);
 void _start(void)
 {
 	/* TODO: handle sp/fp init better -- separate crt0.S? */
-	asm ("law 03000");
-	asm ("dac 209");
-	asm ("law 04000");
-	asm ("dac 208");
+	asm volatile ("law 03000");
+	asm volatile ("dac 0131");
+	asm volatile ("law 04000");
+	asm volatile ("dac 0130");
 
 	foo(20);
 
-	asm ("hlt");
+	asm volatile ("hlt");
 	__builtin_unreachable();
 }
 
 static void putc() {
-	asm ("lio %0" :  : "r"(027) : "io");
-	asm ("tyo");
+	asm volatile ("lio %0" :  : "r"(027) : "$io");
+	asm volatile ("tyo");
 }
 
 static void foo(int n)
diff --git a/pdp1-gcc b/pdp1-gcc
index 5b290ea..5f49091 160000
--- a/pdp1-gcc
+++ b/pdp1-gcc
@@ -1 +1 @@
-Subproject commit 5b290ea6a3755f5ad1d940bb5de7975dab9539b9
+Subproject commit 5f4909120de3159c1a6f7fbdbdc801c354850990