diff --git a/src/bin/um.rs b/src/bin/um.rs
index bc25374..600d39b 100644
--- a/src/bin/um.rs
+++ b/src/bin/um.rs
@@ -45,6 +45,7 @@ impl Console for IoConsole {
   fn write(&mut self, c: u8) {
     let buf = [c;1];
     let _ = std::io::stdout().write(&buf);
+    let _ = std::io::stdout().flush();
   }
 }
 
diff --git a/src/cpu.rs b/src/cpu.rs
index e74678a..510cc2c 100644
--- a/src/cpu.rs
+++ b/src/cpu.rs
@@ -132,7 +132,7 @@ impl Cpu {
     let aidx = self.gr(i.a);
     let aoff = self.gr(i.b) as usize;
     let v = self.gr(i.c);
-    
+    // println!("amd {}[{}]={}", aidx, aoff, v);
     if let Some(arr) = self.arr.get_mut(&aidx){
       if arr.len() > aoff {
         arr[aoff] = v;
@@ -173,9 +173,9 @@ impl Cpu {
   } 
   
   fn handle_nand(&mut self, i:NormalInstruction) -> Result<(), CpuError>{
-    let b = ! self.gr(i.b);
-    let c = ! self.gr(i.c);
-    let a = b & c;
+    let b = self.gr(i.b);
+    let c = self.gr(i.c);
+    let a = !(b & c);
     self.sr(i.a, a);
     Ok(())
   } 
@@ -194,6 +194,7 @@ impl Cpu {
     let v = vec![0; c];
     self.arr.insert(aid, v);
     self.sr(i.b, aid);
+    //println!("alc {} -> {}", c, aid);
     Ok(())
   } 
   
@@ -224,8 +225,11 @@ impl Cpu {
     let aidx = self.gr(i.b);
     let aoff = self.gr(i.c);
     if let Some(arr) = self.arr.get(&aidx){
-      if arr.len() > aoff as usize {
-        self.arr.insert(0, arr.clone());
+      if arr.len() > (aoff as usize) {
+        if aidx > 0 {
+          // println!("cloning {}", aidx);
+          self.arr.insert(0, arr.clone());
+        }
         self.finger = aoff;
         Ok(())
       } else {
@@ -507,9 +511,9 @@ mod tests{
   fn test_div() -> Result<(), CpuError> {
     let pgm = vec!( ezop(5, 1, 2, 3) );
     let mut c = Cpu::new(pgm);
-    c.reg = [0, 0, 2048, 2, 0, 0, 0, 0];
+    c.reg = [0, 0, 2048, 1024, 0, 0, 0, 0];
     c.run(&mut NoConsole{})?;
-    let exp = [0, 1024, 2048, 2, 0, 0, 0, 0];
+    let exp = [0, 2, 2048, 1024, 0, 0, 0, 0];
     assert_eq!(c.reg, exp);
     Ok(())
   }
@@ -530,9 +534,9 @@ mod tests{
   fn test_nand() -> Result<(), CpuError> {
     let pgm = vec!( ezop(6, 1, 2, 3) );
     let mut c = Cpu::new(pgm);
-    c.reg = [0, 0, 0x5a5a00ff, 0xdede00ff, 0, 0, 0, 0];
+    c.reg = [0, 0, 0xff00ff00, 0xffff0000, 0, 0, 0, 0];
     c.run(&mut NoConsole{})?;
-    let exp = [0, 0x2121ff00, 0x5a5a00ff, 0xdede00ff, 0, 0, 0, 0];
+    let exp = [0, 0x00ffff00, 0xff00ff00, 0xffff0000,  0, 0, 0, 0];
     assert_eq!(c.reg, exp);
     Ok(())
   }