diff --git a/regex.tal b/regex.tal
index 93ade47..f964e99 100644
--- a/regex.tal
+++ b/regex.tal
@@ -34,6 +34,7 @@
 %space { #20 emit }
 %newline { #0a emit }
 %print { debug newline }
+%error! { #00 #00 DIV }
 
 ( test -> )
 
@@ -80,7 +81,7 @@
     LDAk #03 EQU ;do-literal JCN2
     LDAk #04 EQU ;do-or JCN2
     LDAk #05 EQU ;do-or JCN2 ( same code as the or case )
-    ( LIT 'x emit ) #00 #00 DIV ( should not happen )
+    error!
 
 @goto-backtrack ( -> bool^ )
     ;stack-exist JSR2 ,&has-stack JCN ( do we have stack? )
@@ -162,14 +163,10 @@
 ( by #ffff #ffff. above that we start with #0000 #0000 )
 ( to signal an empty node. )
 @compile-region ( -> r2* )
-(    #abcd #1234 ;emit-short JSR2 ;emit-short JSR2 space newline )
-    #ffff #ffff ;push4 JSR2
-    #0000 #0000 ;push4 JSR2
+    #ffff #ffff ;push4 JSR2 ( stack delimiter )
+    #0000 #0000 ;push4 JSR2 ( stack frame start )
 @compile-region-loop
     ;read JSR2
-(    LIT '> emit space DUP ;emit-byte JSR2 space print
-    ;emit-stack JSR2
-    ;emit-arena JSR2 newline )
     DUP #00 EQU ;c-done JCN2
     DUP LIT '* EQU ;c-star JCN2
     DUP LIT '| EQU ;c-or   JCN2
@@ -180,79 +177,55 @@
                    ;c-char JMP2
 
 @c-done ( c^ -> r2* )
-(    LIT '$ emit print )
     POP
     ;parens LDA2 #0000 GTH2 ,&mismatched-parens JCN
-    ;unroll-stack JSR2 POP2
-    JMP2r
-    &mismatched-parens ( LIT 'v emit ) #00 #00 DIV
+    ;unroll-stack JSR2 POP2 JMP2r
+    &mismatched-parens error!
 
 @c-or ( c^ -> r2* )
-(    LIT '| emit newline )
     POP
     #0000 #0000 ;push4 JSR2
     ;compile-region-loop JMP2
 
 @c-lpar ( c^ -> r2* )
-(    LIT '( emit newline )
     POP
     ;parens LDA2 INC2 ;parens STA2 ( parens++ )
     ;compile-region JMP2
 
 @c-rpar ( c^ -> r2* )
-(    LIT ') emit newline )
-    POP ( print )
-    ;parens LDA2 #0000 EQU2 ,&mismatched-parens JCN ( print )
-    ;parens LDA2 #0001 SUB2 ;parens STA2 ( parens-- ) ( print )
-(    LIT 'x emit newline )
+    POP
+    ;parens LDA2 #0000 EQU2 ,&mismatched-parens JCN
+    ;parens LDA2 #0001 SUB2 ;parens STA2 ( parens-- )
     ;unroll-stack JSR2
-(    LIT 'u emit print )
-    ;push-next JSR2 ( print )
-(    LIT 'z emit newline )
+    ;push-next JSR2
     ;compile-region-loop JMP2
-    &mismatched-parens ( LIT 'Z emit ) #00 #00 DIV
+    &mismatched-parens error!
 
 @c-dot ( c^ -> r2* )
-(    LIT '. emit newline )
     POP
     ;alloc-dot JSR2 DUP2 ;push-next JSR2
     ;compile-region-loop JMP2
 
 @c-char ( c^ -> r2* )
-(    LIT '@ emit print )
-(    LIT '@ emit DUP ;emit-byte JSR2 newline )
     ;alloc-lit JSR2
-(    LIT '# emit print )
-(    ;emit-stack JSR2
-    ;emit-arena JSR2 )
-    DUP2 ;push-next JSR2 ( print )
-(    LIT '& emit print )
+    DUP2 ;push-next JSR2
     ;compile-region-loop JMP2
 
 ( TODO: escaping rules not quite right )
 @c-esc ( c^ -> r2* )
-(    LIT '\ emit newline )
-    POP ;read JSR2
+    POP
+    ;read JSR2
     ;c-char JMP2
 
 @c-star ( c^ -> regex* )
-(    LIT '* emit print )
-    POP ( print )
+    POP
     ;pop4 JSR2 SWP2 STH2 STH2k ( x1 [x0 x1] )
-(    LIT '! emit space print )
     ;alloc-star JSR2 ( r )
     STH2r STH2kr ( r x1 x0 [x0] )
-(    LIT '0 emit newline )
-(    ;emit-arena JSR2 )
     ;remove-from JSR2 ( r [x0] )
-(    LIT '1 emit newline
-    ;emit-arena JSR2 )
     STH2r OVR2 OVR2 ( r x0 r x0 ) ;set-next JSR2
-    OVR2 #0003 ADD2 #0000 SWP2 STA2 ( fixme )
-(    LIT '2 emit print
-    ;emit-arena JSR2 )
+    OVR2 #0003 ADD2 #0000 SWP2 STA2 ( fixme: manually zeroing next )
     ( r x0 ) SWP2 ;push4 JSR2
-(    LIT '* emit print )
     ;compile-region-loop JMP2
 
 
@@ -264,7 +237,6 @@
     STH2k STA
     STH2kr INC2 STA2
     STH2r
-(    LIT 'e emit print )
     JMP2r
 
 @alloc-empty ( -> r* )
@@ -274,13 +246,12 @@
     #02 ;alloc3 JMP2
 
 @alloc-lit ( c^ -> r* )
-    ( print  )
-    #03 #0000 SWP2 ( print )
-    #04 ;alloc JSR2 ( print )
-    STH2k STA ( print )
-    STH2kr INC2 STA ( print ) 
-    STH2kr #0002 ADD2 STA2 ( print )
-    STH2r ( print )
+    #03 #0000 SWP2
+    #04 ;alloc JSR2
+    STH2k STA
+    STH2kr INC2 STA
+    STH2kr #0002 ADD2 STA2
+    STH2r
     JMP2r
 
 @alloc-or ( right* left* -> r* )
@@ -291,16 +262,11 @@
     STH2r JMP2r
 
 @alloc-star ( expr* -> r* )
-(    LIT '& emit space print )
-(    LIT 'a emit print )
-    #05 ;alloc JSR2 STH2 ( print ) ( expr [r] )
-    #05 STH2kr STA ( print )       ( expr [r] )
-    DUP2 STH2kr INC2 STA2 ( print )     ( expr [r] )
-    #0000 STH2kr #0003 ADD2 STA2 ( print ) ( expr [r] )
-(    LIT 'a emit ;emit-arena JSR2 ;emit-stack JSR2 )
-
-    STH2kr SWP2 ( print ) ( r expr [r] )
-(    LIT 'x emit print )
+    #05 ;alloc JSR2 STH2  ( expr [r] )
+    #05 STH2kr STA        ( expr [r] )
+    DUP2 STH2kr INC2 STA2 ( expr [r] )
+    #0000 STH2kr #0003 ADD2 STA2 ( expr [r] )
+    STH2kr SWP2 ( r expr [r] )
     ;set-next JSR2 ( [r] )
     STH2r JMP2r
 
@@ -351,14 +317,14 @@
     JMP2r
     &is-zero POP2 POP2 ;push4 JSR2 JMP2r
 
-( for nodes (other than 'or') read their 'next' pointer )
+( ( for nodes (other than 'or') read their 'next' pointer )
 @get-next ( r* -> r.next* )
         LDAk #01 NEQ ,&!1 JCN INC2       LDA2 JMP2r
     &!1 LDAk #02 NEQ ,&!2 JCN INC2       LDA2 JMP2r
     &!2 LDAk #03 NEQ ,&!3 JCN #0002 ADD2 LDA2 JMP2r
     &!3 LDAk #04 NEQ ,&!4 JCN INC2       LDA2 JMP2r
     &!4 LDAk #05 NEQ ,&!5 JCN #0003 ADD2 LDA2 JMP2r
-    &!5 ( either #04 (or) or ??? )  ( LIT 'q emit ) #00 #00 DIV
+    &!5 ( either #04 (or) or ??? )  ( LIT 'q emit ) error! )
 
 @set-next-addr ( target* addr* -> )
 (    LIT 'Z emit print )
@@ -379,7 +345,7 @@
             OVR2 OVR2 INC2 ( LIT '{ emit space ) ;set-next-addr JSR2
                 #0003 ADD2 ( LIT '} emit space ) ;set-next-addr JSR2 JMP2r
     &!4 LDAk #05 NEQ ,&!5 JCN #0003 ADD2 ( STA2 ) ;set-next-addr JSR2 JMP2r
-    &!5 ( LIT '? emit LDAk ;emit-byte JSR2 ) #00 #00 DIV
+    &!5 ( LIT '? emit LDAk ;emit-byte JSR2 ) error!
 
 @remove-addr ( target* addr* -> )
 (    LIT 'A emit print )
@@ -401,7 +367,7 @@
 (        LIT 'q emit print )
                 #0003 ADD2 ;remove-addr JSR2 JMP2r
     &!4 LDAk #05 NEQ ,&!5 JCN #0003 ADD2 ;remove-addr JSR2 JMP2r
-    &!5 ( LIT '? emit LDAk ;emit-byte JSR2 ) #00 #00 DIV
+    &!5 ( LIT '? emit LDAk ;emit-byte JSR2 ) error!
 
 ( test cases -------- )
 
@@ -476,9 +442,9 @@
 @stack-exist ( -> bool^ )
     ;stack-pos LDA2 ;stack-bot GTH2 JMP2r
 @assert-avail ( -> )
-    ;stack-avail JSR2 ,&ok JCN #00 #00 DIV &ok JMP2r
+    ;stack-avail JSR2 ,&ok JCN error! &ok JMP2r
 @assert-exist ( -> )
-    ;stack-exist JSR2 ,&ok JCN #00 #00 DIV &ok JMP2r
+    ;stack-exist JSR2 ,&ok JCN error! &ok JMP2r
 
 @emit-stack ( -> )
     space LIT 'n emit LIT '= emit ;stack-pos LDA2 ;stack-bot SUB2 #0004 DIV2 ;emit-short JSR2 LIT ': emit
@@ -529,5 +495,5 @@
     &!2 LDAk #03 NEQ ,&!3 JCN #04 ;emit-n JSR2 ,&loop JMP
     &!3 LDAk #04 NEQ ,&!4 JCN #05 ;emit-n JSR2 ,&loop JMP
     &!4 LDAk #05 NEQ ,&!5 JCN #05 ;emit-n JSR2 ,&loop JMP
-    &!5 LDAk ;emit-byte JSR2 LIT '! emit newline #00 #00 DIV
+    &!5 ( LDAk ;emit-byte JSR2 LIT '! emit newline ) error!
     
\ No newline at end of file