diff --git a/src/asm386/memory.S b/src/asm386/memory.S
index 40e42f0e..8ab38dbf 100644
--- a/src/asm386/memory.S
+++ b/src/asm386/memory.S
@@ -152,45 +152,6 @@
 return80:	movb	$0x80,%al
 		ret
 
-/* unset ioudis flag and read_gc_strobe */
-E(iie_ioudis_off)
-		andl	$~SS_IOUDIS, SN(softswitches)
-		jmp	SN(read_gc_strobe)
-
-/* set ioudis flag and read_gc_strobe */
-E(iie_ioudis_on)
-		orl	$SS_IOUDIS, SN(softswitches)
-		jmp	SN(read_gc_strobe)
-
-/* check ioudis flag and read_gc_strobe */
-E(iie_check_ioudis)
-		call	SN(read_gc_strobe)
-		testl	$SS_IOUDIS, SN(softswitches)		
-		jnz	return80
-		xorb	%al, %al
-		ret
-
-E(iie_dhires_on)
-		testl	$SS_DHIRES, SN(softswitches)
-		jnz	ram_nop
-		orl	$SS_DHIRES, SN(softswitches)
-		call	SN(video_redraw)
-		ret
-
-E(iie_dhires_off)
-		testl	$SS_DHIRES, SN(softswitches)
-		jz	ram_nop
-		andl	$~SS_DHIRES, SN(softswitches)
-		call	SN(video_redraw)
-		ret
-
-/* check dhires flag and read_gc_strobe */
-E(iie_check_dhires)
-		call	SN(read_gc_strobe)
-		testl	$SS_DHIRES, SN(softswitches)
-		jnz	return80
-		ret
-
 E(iie_check_text)
 		testl	$SS_TEXT, SN(softswitches)
 		jnz	return80
diff --git a/src/vm.c b/src/vm.c
index db2d121c..3622e56e 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -696,3 +696,47 @@ GLUE_C_READ(iie_check_altchar)
     return (softswitches & SS_ALTCHAR) ? 0x80 : 0x00;
 }
 
+GLUE_C_READ(iie_ioudis_off)
+{
+    softswitches &= ~SS_IOUDIS;
+    return c_read_gc_strobe(ea);
+}
+
+GLUE_C_READ(iie_ioudis_on)
+{
+    softswitches |= SS_IOUDIS;
+    return c_read_gc_strobe(ea);
+}
+
+GLUE_C_READ(iie_check_ioudis)
+{
+    c_read_gc_strobe(ea);
+    return (softswitches & SS_IOUDIS) ? 0x80 : 0x00;
+}
+
+GLUE_C_READ(iie_dhires_on)
+{
+    // FIXME : does this depend on IOUDIS?
+    if (!(softswitches & SS_DHIRES)) {
+        softswitches |= SS_DHIRES;
+        video_redraw();
+    }
+    return 0x0;
+}
+
+GLUE_C_READ(iie_dhires_off)
+{
+    // FIXME : does this depend on IOUDIS?
+    if (softswitches & SS_DHIRES) {
+        softswitches &= ~SS_DHIRES;
+        video_redraw();
+    }
+    return 0x0;
+}
+
+GLUE_C_READ(iie_check_dhires)
+{
+    c_read_gc_strobe(ea); // HACK FIXME : is this correct?
+    return (softswitches & SS_DHIRES) ? 0x80 : 0x00;
+}
+