diff --git a/i.c b/i.c
index a33bf16..71acaec 100644
--- a/i.c
+++ b/i.c
@@ -573,6 +573,22 @@ define_instruction(panic) {
   unwindi(0); 
 }
 
+define_instruction(abort) {
+  /* exit code ignored */
+  abort();
+  unwindi(0);
+}
+
+define_instruction(exit) {
+  int excode;
+  if (ac == bool_obj(0)) excode = 1;
+  else if (ac == bool_obj(1)) excode = 0;
+  else if (is_fixnum(ac)) excode = (int)get_fixnum(ac);
+  else excode = 1;
+  exit(excode);
+  unwindi(0);
+}
+
 
 define_instruction(lit) { 
   ac = *ip++; 
diff --git a/i.h b/i.h
index 5cd0254..017d8f5 100644
--- a/i.h
+++ b/i.h
@@ -513,6 +513,8 @@ declare_instruction(clock,      "Z3",           0,  "current-jiffy",
 declare_instruction(clops,      "Z4",           0,  "jiffies-per-second",       '0', AUTOGL)
 declare_instruction(cursec,     "Z5",           0,  "current-second",           '0', AUTOGL)
 declare_instruction(panic,      "Z7",           0,  "%panic",                   '2', AUTOGL)
+declare_instruction(abort,      "Z8\0t",        0,  "%abort",                   'u', AUTOGL)
+declare_instruction(exit,       "Z9\0t",        0,  "%exit",                    'u', AUTOGL)
 
 /* serialization and deserialization instructions */             
 declare_instruction(igp,        "U0",           0,  "integrable?",              '1', AUTOGL)
diff --git a/s.c b/s.c
index aa276d8..3321455 100644
--- a/s.c
+++ b/s.c
@@ -171,6 +171,27 @@ char *s_code[] = {
   "l3:y12:syntax-rules;n;l2:l2:y1:_;y1:x;;l2:y11:delay-force;l2:y12:make-"
   "promise;y1:x;;;;",
 
+  "C", 0,
+  "&0{%2${.2,.4[01},#0.2,.1,&2{%2.1?{.0:!0]2}.0,:1[21}%x,.3,.2,&2{%1${.2,"
+  ":1[01}:!0]1}%x,.2,&1{%0:0^]0}%x,&3{|00|11|22%%}]3}%x,&0{%1#0.0,&1{%2.1"
+  "?{.0:!0]2}.0]2}%x,.1,&1{%1.0:!0]1}%x,.2,&1{%0:0^]0}%x,&3{|00|11|22%%}]"
+  "1}%x,&2{|10|21%%}@!(y14:make-parameter)",
+
+  "S", "%parameterize-loop",
+  "l4:y12:syntax-rules;n;l2:l4:y1:_;l2:l5:y5:param;y5:value;y1:p;y3:old;y"
+  "3:new;;y3:...;;n;y4:body;;l3:y3:let;l2:l2:y1:p;y5:param;;y3:...;;l3:y3"
+  ":let;l4:l2:y3:old;l1:y1:p;;;y3:...;l2:y3:new;l3:y1:p;y5:value;f;;;y3:."
+  "..;;l4:y12:dynamic-wind;l4:y6:lambda;n;l3:y1:p;y3:new;t;;y3:...;;py6:l"
+  "ambda;pn;y4:body;;;l4:y6:lambda;n;l3:y1:p;y3:old;t;;y3:...;;;;;;l2:l4:"
+  "y1:_;y4:args;pl2:y5:param;y5:value;;y4:rest;;y4:body;;l4:y18:%25parame"
+  "terize-loop;pl5:y5:param;y5:value;y1:p;y3:old;y3:new;;y4:args;;y4:rest"
+  ";y4:body;;;",
+
+  "S", "parameterize",
+  "l3:y12:syntax-rules;n;l2:py1:_;pl2:l2:y5:param;y5:value;;y3:...;;y4:bo"
+  "dy;;;l4:y18:%25parameterize-loop;n;l2:l2:y5:param;y5:value;;y3:...;;y4"
+  ":body;;;",
+
   "P", "new-record-type",
   "%2.1,.1c]2",
 
@@ -581,11 +602,122 @@ char *s_code[] = {
   "I+,:3^[11}.!0.0^_1[41}${.2,.5c,@(y13:%25vector->list),@(y5:%25map1)[02"
   "},.2c,@(y9:%25for-each),@(y13:apply-to-list)[32",
 
+  "P", "abort",
+  "%0tZ8]0",
+
+  "P", "reset",
+  "%0'1Z9]0",
+
+  "P", "set-reset-handler!",
+  "%1.0@!(y5:reset)]1",
+
+  "P", "print-error-message",
+  "%3,,,#0#1#2.1,&1{%2.0p?{.0a~?{${.3,'(s2:: ),@(y12:write-string)[02}.1,"
+  ".1d,:0^[22}.0aY0?{${.3,'(s4: in ),@(y12:write-string)[02}.1,.1aW5${.3,"
+  "'(s2:: ),@(y12:write-string)[02}.1,.1d,:0^[22}${.3,'(s2:: ),@(y12:writ"
+  "e-string)[02}.1,.1,:0^[22}]2}.!0.2,&1{%2.0p?{.0aS0?{.1,.1aW4.1,.1d,:0^"
+  "[22}.1,.1,:0^[22}]2}.!1.2,&1{%2.0p?{.1,'(c )W0.1,.1aW5.1,.1d,:0^[22}]2"
+  "}.!2.3S0,.0?{.0}{.4Y0}_1?{${.7,.6,@(y12:write-string)[02}}{${.7,'(s5:E"
+  "rror),@(y12:write-string)[02}}${.7,.7,.4^[02}.5W6]6",
+
+  "P", "simple-error",
+  "%!0P12,.0W6${.2,.4,'(s5:Error),@(y19:print-error-message)[03}@(y5:rese"
+  "t)[20",
+
+  "P", "assertion-violation",
+  "%!0P12,.0W6${.2,.4,'(s19:Assertion violation),@(y19:print-error-messag"
+  "e)[03}'1Z9]2",
+
+  "C", 0,
+  "${'(l3:y4:kind;y7:message;y9:irritants;),'(y14:<error-object>),@(y15:n"
+  "ew-record-type)[02}@!(y14:<error-object>)",
+
+  "P", "error-object",
+  "%3f,'3,@(y14:<error-object>)O2,.1,'0,.2O5.2,'1,.2O5.3,'2,.2O5.0]4",
+
+  "P", "error-object?",
+  "%1@(y14:<error-object>),.1O0]1",
+
+  "P", "error-object-kind",
+  "%1'0,.1O4]1",
+
+  "P", "error-object-message",
+  "%1'1,.1O4]1",
+
+  "P", "error-object-irritants",
+  "%1'2,.1O4]1",
+
   "P", "error",
-  "%!1.0,.2Z7]2",
+  "%!1${.2,.4,f,@(y12:error-object)[03},@(y5:raise)[21",
+
+  "C", 0,
+  "${,#0&0{%1${.2,@(y13:error-object?)[01}?{${.2,@(y22:error-object-irrit"
+  "ants)[01},${.3,@(y20:error-object-message)[01}c,${.3,@(y17:error-objec"
+  "t-kind)[01}c,@(y12:simple-error),@(y13:apply-to-list)[12}.0,'(s19:unha"
+  "ndled exception),f,@(y12:simple-error)[13}%x,.1,&1{%0:0^]0}%x,&2{|00|1"
+  "1%%}.!0.0^_1,@(y14:make-parameter)[01}@!(y25:current-exception-handler"
+  ")",
+
+  "P", "with-exception-handler",
+  "%2${@(y25:current-exception-handler)[00},@(y25:current-exception-handl"
+  "er),${f,.5,&1{%1.0,:0[11}%x,.5,&1{%0:0]0}%x,&2{|00|11%%},.4[02},${.3[0"
+  "0},.0,.3,&2{%0t,:1,:0[02},.6,&1{%0:0[00},.3,.5,&2{%0t,:1,:0[02},@(y12:"
+  "dynamic-wind)[63",
+
+  "P", "raise",
+  "%1${@(y25:current-exception-handler)[00},@(y25:current-exception-handl"
+  "er),${f,${.6[00},.4[02},${.3[00},.0,.3,&2{%0t,:1,:0[02},.4,.6,&2{%0${:"
+  "0,:1[01}${:0,:1,l2,'(s26:exception handler returned),'(y5:raise),@(y12"
+  ":error-object)[03},@(y5:raise)[01},.3,.5,&2{%0t,:1,:0[02},@(y12:dynami"
+  "c-wind)[53",
+
+  "P", "raise-continuable",
+  "%1${@(y25:current-exception-handler)[00},@(y25:current-exception-handl"
+  "er),${f,${.6[00},.4[02},${.3[00},.0,.3,&2{%0t,:1,:0[02},.5,.5,&2{%0:1,"
+  ":0[01},.3,.5,&2{%0t,:1,:0[02},@(y12:dynamic-wind)[53",
+
+  "S", "%guard-aux",
+  "l9:y12:syntax-rules;l2:y4:else;y2:=>;;l2:l3:y1:_;y7:reraise;l4:y4:else"
+  ";y7:result1;y7:result2;y3:...;;;l4:y5:begin;y7:result1;y7:result2;y3:."
+  "..;;;l2:l3:y1:_;y7:reraise;l3:y4:test;y2:=>;y6:result;;;l3:y3:let;l1:l"
+  "2:y4:temp;y4:test;;;l4:y2:if;y4:temp;l2:y6:result;y4:temp;;y7:reraise;"
+  ";;;l2:l6:y1:_;y7:reraise;l3:y4:test;y2:=>;y6:result;;y7:clause1;y7:cla"
+  "use2;y3:...;;l3:y3:let;l1:l2:y4:temp;y4:test;;;l4:y2:if;y4:temp;l2:y6:"
+  "result;y4:temp;;l5:y10:%25guard-aux;y7:reraise;y7:clause1;y7:clause2;y"
+  "3:...;;;;;l2:l3:y1:_;y7:reraise;l1:y4:test;;;l3:y2:or;y4:test;y7:rerai"
+  "se;;;l2:l6:y1:_;y7:reraise;l1:y4:test;;y7:clause1;y7:clause2;y3:...;;l"
+  "3:y3:let;l1:l2:y4:temp;y4:test;;;l4:y2:if;y4:temp;y4:temp;l5:y10:%25gu"
+  "ard-aux;y7:reraise;y7:clause1;y7:clause2;y3:...;;;;;l2:l3:y1:_;y7:rera"
+  "ise;l4:y4:test;y7:result1;y7:result2;y3:...;;;l4:y2:if;y4:test;l4:y5:b"
+  "egin;y7:result1;y7:result2;y3:...;;y7:reraise;;;l2:l6:y1:_;y7:reraise;"
+  "l4:y4:test;y7:result1;y7:result2;y3:...;;y7:clause1;y7:clause2;y3:...;"
+  ";l4:y2:if;y4:test;l4:y5:begin;y7:result1;y7:result2;y3:...;;l5:y10:%25"
+  "guard-aux;y7:reraise;y7:clause1;y7:clause2;y3:...;;;;",
+
+  "S", "guard",
+  "l3:y12:syntax-rules;n;l2:l5:y5:guard;l3:y3:var;y6:clause;y3:...;;y2:e1"
+  ";y2:e2;y3:...;;l1:l2:y7:call/cc;l3:y6:lambda;l1:y7:guard-k;;l3:y22:wit"
+  "h-exception-handler;l3:y6:lambda;l1:y9:condition;;l1:l2:y7:call/cc;l3:"
+  "y6:lambda;l1:y9:handler-k;;l2:y7:guard-k;l3:y6:lambda;n;l3:y3:let;l1:l"
+  "2:y3:var;y9:condition;;;l4:y10:%25guard-aux;l2:y9:handler-k;l3:y6:lamb"
+  "da;n;l2:y17:raise-continuable;y9:condition;;;;y6:clause;y3:...;;;;;;;;"
+  ";l3:y6:lambda;n;l3:y16:call-with-values;l5:y6:lambda;n;y2:e1;y2:e2;y3:"
+  "...;;l3:y6:lambda;y4:args;l2:y7:guard-k;l3:y6:lambda;n;l3:y5:apply;y6:"
+  "values;y4:args;;;;;;;;;;;;",
 
   "P", "read-error",
-  "%!1.0,.2Z7]2",
+  "%!1${.2,.4,'(y4:read),@(y12:error-object)[03},@(y5:raise)[21",
+
+  "P", "read-error?",
+  "%1${.2,@(y13:error-object?)[01}?{'(y4:read),${.3,@(y17:error-object-ki"
+  "nd)[01}q]1}f]1",
+
+  "P", "file-error",
+  "%!1${.2,.4,'(y4:file),@(y12:error-object)[03},@(y5:raise)[21",
+
+  "P", "file-error?",
+  "%1${.2,@(y13:error-object?)[01}?{'(y4:file),${.3,@(y17:error-object-ki"
+  "nd)[01}q]1}f]1",
 
   "P", "port?",
   "%1.0P00,.0?{.0]2}.1P01]2",
diff --git a/src/s.scm b/src/s.scm
index 57c98a7..4fcf16c 100644
--- a/src/s.scm
+++ b/src/s.scm
@@ -222,6 +222,42 @@
   (syntax-rules () [(_ x) (delay-force (make-promise x))]))
 
 
+;---------------------------------------------------------------------------------------------
+; Dynamic bindings
+;---------------------------------------------------------------------------------------------
+
+(define make-parameter
+  (case-lambda
+    [(value) 
+     (case-lambda 
+       [() value]
+       [(x) (set! value x)]
+       [(x s) (if s (set! value x) x)])]
+    [(init converter)
+     (let ([value (converter init)])
+       (case-lambda 
+         [() value]
+         [(x) (set! value (converter x))]
+         [(x s) (if s (set! value x) (converter x))]))]))
+
+(define-syntax %parameterize-loop
+  (syntax-rules ()
+    [(_ ([param value p old new] ...) () body)
+     (let ([p param] ...)
+       (let ([old (p)] ... [new (p value #f)] ...)
+         (dynamic-wind
+           (lambda () (p new #t) ...)
+           (lambda () . body)
+           (lambda () (p old #t) ...))))]
+    [(_ args ([param value] . rest) body)
+     (%parameterize-loop ([param value p old new] . args) rest body)]))
+
+(define-syntax parameterize
+  (syntax-rules ()
+    [(_ ([param value] ...) . body)
+     (%parameterize-loop () ([param value] ...) body)]))
+
+
 ;---------------------------------------------------------------------------------------------
 ; Record type definitions
 ;---------------------------------------------------------------------------------------------
@@ -1144,20 +1180,157 @@
 
 ;TBD:
 ;
-;with-exception-handler
-;raise
-;raise-continuable
-;error-object?
-;error-object-message
-;error-object-irritants
+; (with-exception-handler handler thunk)
+; (raise obj)
+; (raise-continuable obj)
+; (error-object? x)
+; (error-object-message e)
+; (error-object-irritants e)
 ;read-error?
 ;file-error?
 
-(define (error msg . args) 
-  (%panic msg args)) ; should work for now
+
+(define (abort) (%abort))
+
+(define (reset) (%exit 1))
+
+(define (set-reset-handler! fn) (set! reset fn))
+
+(define (print-error-message prefix args ep)
+  (define (pr-where args ep)
+    (when (pair? args) 
+      (cond [(not (car args)) 
+             (write-string ": " ep)
+             (pr-msg (cdr args) ep)]
+            [(symbol? (car args)) 
+             (write-string " in " ep) (write (car args) ep) (write-string ": " ep)
+             (pr-msg (cdr args) ep)]
+            [else 
+             (write-string ": " ep)
+             (pr-msg args ep)]))) 
+  (define (pr-msg args ep)
+    (when (pair? args) 
+      (cond [(string? (car args))
+             (display (car args) ep)
+             (pr-rest (cdr args) ep)]
+            [else (pr-rest args ep)])))
+   (define (pr-rest args ep)
+     (when (pair? args)
+       (write-char #\space ep) (write (car args) ep)
+       (pr-rest (cdr args) ep)))
+   (cond [(or (string? prefix) (symbol? prefix)) 
+          (write-string prefix ep)]
+         [else (write-string "Error" ep)])
+   (pr-where args ep)
+   (newline ep))
+
+(define (simple-error . args)
+  (let ([ep (current-error-port)])
+    (newline ep)
+    (print-error-message "Error" args ep)
+    (reset)))
+
+(define (assertion-violation . args)
+  (let ([ep (current-error-port)])
+    (newline ep)
+    (print-error-message "Assertion violation" args ep)
+    (%exit 1)))
+
+(define-record-type <error-object>
+  (error-object kind message irritants)
+  error-object?
+  (kind error-object-kind)
+  (message error-object-message)
+  (irritants error-object-irritants))
+
+(define (error msg . args)
+  (raise (error-object #f msg args)))
+
+(define current-exception-handler 
+  (make-parameter
+    (letrec 
+      ([default-handler
+        (case-lambda 
+          [() default-handler] ;this one its own parent 
+          [(obj) 
+           (if (error-object? obj)
+               (apply simple-error (error-object-kind obj) (error-object-message obj) (error-object-irritants obj)) 
+               (simple-error #f "unhandled exception" obj))])])
+      default-handler)))
+
+(define (with-exception-handler handler thunk)
+  (let ([eh (current-exception-handler)])
+    (parameterize ([current-exception-handler (case-lambda [() eh] [(obj) (handler obj)])])
+      (thunk)))) 
+
+(define (raise obj)
+  (let ([eh (current-exception-handler)])
+    (parameterize ([current-exception-handler (eh)])
+      (eh obj)
+      (raise (error-object 'raise "exception handler returned" (list eh obj))))))
+
+(define (raise-continuable obj)
+  (let ([eh (current-exception-handler)])
+    (parameterize ([current-exception-handler (eh)])
+      (eh obj))))
+
+(define-syntax %guard-aux
+  (syntax-rules (else =>)
+    [(_ reraise (else result1 result2 ...))
+     (begin result1 result2 ...)]
+    [(_ reraise (test => result))
+     (let ([temp test]) (if temp (result temp) reraise))]
+    [(_ reraise (test => result) clause1 clause2 ...)
+     (let ([temp test])
+       (if temp
+           (result temp)
+           (%guard-aux reraise clause1 clause2 ...)))]
+    [(_ reraise (test)) (or test reraise)]
+    [(_ reraise (test) clause1 clause2 ...)
+     (let ([temp test])
+       (if temp temp (%guard-aux reraise clause1 clause2 ...)))]
+    [(_ reraise (test result1 result2 ...))
+     (if test (begin result1 result2 ...) reraise)]
+    [(_ reraise (test result1 result2 ...) clause1 clause2 ...)
+     (if test
+         (begin result1 result2 ...)
+         (%guard-aux reraise clause1 clause2 ...))]))
+
+(define-syntax guard
+  (syntax-rules ()
+    [(guard (var clause ...) e1 e2 ...)
+    ((call/cc
+      (lambda (guard-k)
+        (with-exception-handler
+          (lambda (condition)
+            ((call/cc
+                (lambda (handler-k)
+                  (guard-k
+                    (lambda ()
+                      (let ([var condition])
+                        (%guard-aux
+                          (handler-k
+                            (lambda ()
+                              (raise-continuable condition)))
+                          clause
+                          ...))))))))
+          (lambda ()
+            (call-with-values
+              (lambda () e1 e2 ...)
+              (lambda args
+                (guard-k (lambda () (apply values args))))))))))]))
 
 (define (read-error msg . args)
-  (%panic msg args)) ; should work for now
+  (raise (error-object 'read msg args)))
+
+(define (read-error? obj)
+  (and (error-object? obj) (eq? (error-object-kind obj) 'read))) 
+
+(define (file-error msg . args)
+  (raise (error-object 'file msg args)))
+
+(define (file-error? obj)
+  (and (error-object? obj) (eq? (error-object-kind obj) 'file))) 
 
 
 ;---------------------------------------------------------------------------------------------