diff --git a/asm.py b/asm.py
index 75aeba9..77a8676 100755
--- a/asm.py
+++ b/asm.py
@@ -2,6 +2,7 @@
 
 from types import SimpleNamespace
 from rply import ParserGenerator, LexerGenerator
+import re
 import struct
 
 OPS = {
@@ -153,7 +154,7 @@ tokens = [
 ]
 
 for name, regex in tokens:
-    lg.add(name, regex)
+    lg.add(name, regex, re.IGNORECASE)
 
 #lg.ignore(r'\s+')
 lg.ignore(r'[ \t\v\f]+')
@@ -212,8 +213,10 @@ def op_op2(p):
     return ASM(label=None, op=p[0].getstr(), b=p[1], a=p[3])
 
 @pg.production("op : OP1 arg_a")
+# Some source code has a comma before the argument
+@pg.production("op : OP1 COMMA arg_a")
 def op_op1(p):
-    return ASM(label=None, op=p[0].getstr(), a=p[1], b=None)
+    return ASM(label=None, op=p[0].getstr(), a=p[-1], b=None)
 
 @pg.production("op : DIRN exprlist")
 def op_dirn(p):
@@ -393,6 +396,7 @@ if __name__ == '__main__':
                 print(["%04x" % x for x in words])
                 for w in words:
                     binimage += struct.pack("<H", w)
+                    #binimage += struct.pack(">H", w)
         outfilename = filename[:filename.rfind('.')]+'.bin'
         with open(outfilename, 'wb') as binfile:
             binfile.write(binimage)
diff --git a/dsim.c b/dsim.c
index 529cd33..bef7e34 100644
--- a/dsim.c
+++ b/dsim.c
@@ -225,8 +225,8 @@ void oDIV(uint16_t *a, uint16_t *b)
     if (*a) {
         wb = *b;
         wt = (wb<<16) / *a;
-        rex = wt&0xffff;
         *b = wt>>16;
+        rex = wt&0xffff;
     } else {
         *b = rex = 0;
     }
@@ -234,9 +234,14 @@ void oDIV(uint16_t *a, uint16_t *b)
 
 void oDVI(uint16_t *a, uint16_t *b)
 {
+    int32_t wa, wb, wt;
+
     if (*a) {
-        rex = ((int16_t)*b<<16) / (int16_t)*a;
-        *b = (int16_t)*b / (int16_t)*a;
+        wa = (*a << 16) >> 16;
+        wb = (*b << 16) >> 16;
+        wt = (wb<<16) / wa;
+        *b = wt>>16;
+        rex = wt&0xffff;
     } else {
         *b = rex = 0;
     }
@@ -298,8 +303,8 @@ void oSHL(uint16_t *a, uint16_t *b)
     uint32_t t;
 
     t = ((uint32_t)*b) << *a;
-    rex = t >> 16;
     *b = t;
+    rex = t >> 16;
 }
 
 #define DOIF(c) if (!(c)) { skip_next = true; ticks++; }
@@ -484,7 +489,7 @@ void next()
     if ((!intq_en) && (intq_size > 0) && (!skip_next)) {
         i = intq_pop();
         if (ria != 0) {
-            printf("Firing interrupt with message 0x%04x\n", i);
+            //printf("Firing interrupt with message 0x%04x\n", i);
             intq_en = true;
             ram[--rsp] = rpc;
             ram[--rsp] = ra;