diff --git a/Makefile b/Makefile
index fb216c1..f25f662 100644
--- a/Makefile
+++ b/Makefile
@@ -20,7 +20,7 @@ test: kas out/a.out
 	@out/k.exe out/a.out > out/stdout.txt
 	@echo "output:"
 	@echo ">>>>>>>>"
-	@cat out/stdout.txt
+	@cat -v out/stdout.txt
 	@echo
 	@echo "<<<<<<<<"
 	@echo
diff --git a/as/k-as.py b/as/k-as.py
index 4d48351..dda27ad 100755
--- a/as/k-as.py
+++ b/as/k-as.py
@@ -156,11 +156,20 @@ def parse():
         if len(line) == 0:
             continue
 
+        quote = False
         for i in range(len(line)):
-            if line[i] in '#;@!/':
+            if line[i] in "'\"":
+                quote = not quote
+
+            if line[i] in '#;@!/' and not quote:
                 line = line[:i].rstrip()
                 break
 
+        if quote:
+            print("Unterminated string in line: {}".format(line))
+            leave()
+            sys.exit(1)
+
         if len(line) == 0:
             continue
 
diff --git a/dos/main.k b/dos/main.k
index 5c695a6..ecbb58d 100644
--- a/dos/main.k
+++ b/dos/main.k
@@ -7,22 +7,28 @@
 main:
     enter
 
+    mov ax0, .buf
+    call print
+
+    prn 10
     mov ax0, .msg
     call print
 
     mov ax0, .buf
     mov ax1, .msg
-    call strrev
+    mov ax2, 5
+    call strnzcpy
 
     prn 10
     mov ax0, .buf
-    call print
+    mov ax1, 10
+    call print_n
 
     leave
     ret
 
-.msg = "Hello World :)"
-.buf = "!!!!!!!!!!!!!!!!!!!!!"
+.msg = "HelloWorld :)"
+.buf = "!!!!!!!!!!!!!"
 
 ;
 ; Exit function
diff --git a/dos/prn/print.k b/dos/prn/print.k
index 7c5a41e..a05b2ef 100644
--- a/dos/prn/print.k
+++ b/dos/prn/print.k
@@ -16,6 +16,7 @@ print:
 .1:
     test b[ax0], b[ax0]
     cjmpz .2
+
     prn b[ax0]
     inc ax0
     loop .1
diff --git a/dos/str/strcpy.k b/dos/str/strcpy.k
index 819031c..0b1d092 100644
--- a/dos/str/strcpy.k
+++ b/dos/str/strcpy.k
@@ -5,26 +5,54 @@
 ; void strcpy(char *, const char *)
 ;
 strcpy:
+    mov b[ax0], b[ax1]
+
     test b[ax1], b[ax1]
-    cmovz b[ax0], 0
     cretz
 
-.1:
-    test b[ax1], b[ax1]
-    cmovz b[ax0], 0
-    cretz
-
-    ret
+    inc ax0
+    inc ax1
+    jmp strcpy
 
 ;
 ; void strncpy(char *, const char *, int)
 ;
 strncpy:
+    mov rcx, ax2
+    jcxz .2
+    dec rcx
+
+.1:
+    mov b[ax0], b[ax1]
+
+    test b[ax1], b[ax1]
+    cretz
+
+    inc ax0
+    inc ax1
+    loop .1
+
+.2:
     ret
 
 ;
 ; void strnzcpy(char *, const char *, int)
 ;
 strnzcpy:
-    ret
+    mov rcx, ax2
+    jcxz .2
+    dec rcx
 
+.1:
+    mov b[ax0], b[ax1]
+
+    test b[ax1], b[ax1]
+    cretz
+
+    inc ax0
+    inc ax1
+    loop .1
+
+.2:
+    mov b[ax0], 0
+    ret
diff --git a/dos/str/strlen.k b/dos/str/strlen.k
index 9bc9a58..c9e2d35 100644
--- a/dos/str/strlen.k
+++ b/dos/str/strlen.k
@@ -21,7 +21,7 @@ strlen:
 strnlen:
     xor rax, rax
     mov rcx, ax1
-    ;jcxz .2
+    jcxz .2
     dec rcx
 
 .1:
@@ -32,4 +32,5 @@ strnlen:
     inc ax0
     loop .1
 
+.2:
     ret
diff --git a/pc/instrs/instrs.c b/pc/instrs/instrs.c
index a791f7f..28fdb65 100644
--- a/pc/instrs/instrs.c
+++ b/pc/instrs/instrs.c
@@ -22,13 +22,14 @@ IMPL_START_1(prn)
         log("prn warning: large access size\n");
     }
 
+/*
     if (!(v1 >= ' ' && v1 < 128) && v1 != '\t' && v1 != '\n') {
         log("prn on invalid character: %ld\n", v1);
+        return;
     }
+*/
 
-    else {
-        putchar((int)v1);
-    }
+    putchar((int)v1);
 }
 IMPL_END;
 
diff --git a/pc/mem.c b/pc/mem.c
index cf1d95c..bc81b36 100644
--- a/pc/mem.c
+++ b/pc/mem.c
@@ -95,22 +95,12 @@ void writemem8(ctx_t *ctx, ulong val, ulong addr)
     ushort v = ctx->mp[real];
 
     if (!(addr % 2)) {
-        ctx->mp[real] = ((v & 0xFF00) << 8) | (val & 0xFF);
-    }
-
-    else {
-        ctx->mp[real] = (v & 0xFF) | (((val & 0xFF) << 8));
-    }
-
-/*
-    if (addr % 2) {
         ctx->mp[real] = (v & 0xFF00) | (val & 0xFF);
     }
 
     else {
         ctx->mp[real] = (v & 0xFF) | (((val & 0xFF) << 8));
     }
-*/
 }
 
 void writemem16(ctx_t *ctx, ulong val, ulong addr)