diff --git a/beautiful-racket/br/demo/hdl-tst/expander.rkt b/beautiful-racket/br/demo/hdl-tst/expander.rkt
index 49b0998..b6cc053 100644
--- a/beautiful-racket/br/demo/hdl-tst/expander.rkt
+++ b/beautiful-racket/br/demo/hdl-tst/expander.rkt
@@ -1,4 +1,5 @@
 #lang br
+(require (for-syntax br/syntax))
 (provide #%top-interaction #%module-begin #%datum (rename-out [my-top #%top]) #%app
          (all-defined-out))
 
@@ -10,25 +11,27 @@
 
 (define #'(tst-program _arg ...) #'(begin _arg ...))
 
+(begin-for-syntax
+  (define-scope blue))
 
 (define #'(header-expr _filename (_colid ... _outid))
   (with-syntax* ([filename-string (symbol->string (syntax->datum #'_filename))]
-                 [procname (string->symbol (cadr (regexp-match #rx"^(.*)\\.hdl$"(symbol->string (syntax->datum #'_filename)))))]
-                 [output (syntax-local-introduce (datum->syntax #f 'output))])
-    #'(begin
-        (provide (all-defined-out))
-        (define procname
-          (dynamic-require (findf file-exists?
-                                  (list filename-string (format "~a.rkt" filename-string))) 'procname))
-        (display-header '_colid ... '_outid)
-        (define _colid (make-parameter 0)) ...
-        (define (_outid)
-          (keyword-apply procname
-                         (map (compose1 string->keyword symbol->string) (list '_colid ...))
-                         (list (_colid) ...) null))
-        
-        (define (output)
-          (display-values (_colid) ... (_outid))))))
+                 [procname (string->symbol (cadr (regexp-match #rx"^(.*)\\.hdl$"(symbol->string (syntax->datum #'_filename)))))])
+    (with-blue-binding-form (output)
+                            #'(begin
+                                (provide (all-defined-out))
+                                (define procname
+                                  (dynamic-require (findf file-exists?
+                                                          (list filename-string (format "~a.rkt" filename-string))) 'procname))
+                                (display-header '_colid ... '_outid)
+                                (define _colid (make-parameter 0)) ...
+                                (define (_outid)
+                                  (keyword-apply procname
+                                                 (map (compose1 string->keyword symbol->string) (list '_colid ...))
+                                                 (list (_colid) ...) null))
+                                
+                                (define (output)
+                                  (display-values (_colid) ... (_outid)))))))
 
 (define #'(display-header _sym ...)
   #'(begin
@@ -47,5 +50,5 @@
 (define #'eval-expr #'void)
 
 (define #'(output-expr)
-  (inject-syntax ([#'output 'output])
-                 #'(output)))
+  (with-blue-identifiers (output)
+                        #'(output)))
diff --git a/beautiful-racket/br/demo/hdl/And.tst b/beautiful-racket/br/demo/hdl/And.tst.rkt
similarity index 100%
rename from beautiful-racket/br/demo/hdl/And.tst
rename to beautiful-racket/br/demo/hdl/And.tst.rkt
diff --git a/beautiful-racket/br/demo/hdl/DMux.hdl b/beautiful-racket/br/demo/hdl/DMux.hdl.rkt
similarity index 100%
rename from beautiful-racket/br/demo/hdl/DMux.hdl
rename to beautiful-racket/br/demo/hdl/DMux.hdl.rkt
diff --git a/beautiful-racket/br/demo/hdl/Dmux.tst.rkt b/beautiful-racket/br/demo/hdl/Dmux.tst.rkt
index efaf4bd..261390f 100644
--- a/beautiful-racket/br/demo/hdl/Dmux.tst.rkt
+++ b/beautiful-racket/br/demo/hdl/Dmux.tst.rkt
@@ -1,4 +1,4 @@
-#lang br/demo/hdl/tst
+#lang br/demo/hdl-tst
 
 // This file is part of www.nand2tetris.org
 // and the book "The Elements of Computing Systems"
diff --git a/beautiful-racket/br/demo/hdl/Nand.hdl b/beautiful-racket/br/demo/hdl/Nand.hdl
deleted file mode 100644
index 8655fa2..0000000
--- a/beautiful-racket/br/demo/hdl/Nand.hdl
+++ /dev/null
@@ -1,13 +0,0 @@
-#lang br
-
-(define+provide (Nand #:a a #:b b)
-  (if (< (+ a b) 2)
-      1
-      0))
-
-(module+ test
-  (require rackunit)
-  (check-equal? (Nand #:a 0 #:b 0) 1)
-  (check-equal? (Nand #:a 0 #:b 1) 1)
-  (check-equal? (Nand #:a 1 #:b 0) 1)
-  (check-equal? (Nand #:a 1 #:b 1) 0))
diff --git a/beautiful-racket/br/demo/hdl/Nand.hdl.rkt b/beautiful-racket/br/demo/hdl/Nand.hdl.rkt
new file mode 100644
index 0000000..40b2504
--- /dev/null
+++ b/beautiful-racket/br/demo/hdl/Nand.hdl.rkt
@@ -0,0 +1,28 @@
+#lang br
+
+(define Nand-a
+  (let ([Nand-a-val 0])
+    (λ ([val #f])
+      (if val
+          (set! Nand-a-val val)
+          Nand-a-val))))
+
+(define Nand-b
+  (let ([Nand-b-val 0])
+    (λ ([val #f])
+      (if val
+          (set! Nand-b-val val)
+          Nand-b-val))))
+
+
+(define (Nand-out)
+  (if (< (+ (Nand-a) (Nand-b)) 2)
+      1
+      0))
+
+(module+ test
+  (require rackunit)
+  (check-equal? (begin (Nand-a 0) (Nand-b 0) (Nand-out)) 1)
+  (check-equal? (begin (Nand-a 0) (Nand-b 1) (Nand-out)) 1)
+  (check-equal? (begin (Nand-a 1) (Nand-b 0) (Nand-out)) 1)
+  (check-equal? (begin (Nand-a 1) (Nand-b 1) (Nand-out)) 0))
diff --git a/beautiful-racket/br/demo/hdl/Nand.tst b/beautiful-racket/br/demo/hdl/Nand.tst.rkt
similarity index 89%
rename from beautiful-racket/br/demo/hdl/Nand.tst
rename to beautiful-racket/br/demo/hdl/Nand.tst.rkt
index 8d5914b..3ada897 100644
--- a/beautiful-racket/br/demo/hdl/Nand.tst
+++ b/beautiful-racket/br/demo/hdl/Nand.tst.rkt
@@ -1,4 +1,4 @@
-#lang br/demo/hdl/tst
+#lang br/demo/hdl-tst
 
 /* nand */
 
diff --git a/beautiful-racket/br/demo/hdl/Not.hdl b/beautiful-racket/br/demo/hdl/Not.hdl.rkt
similarity index 100%
rename from beautiful-racket/br/demo/hdl/Not.hdl
rename to beautiful-racket/br/demo/hdl/Not.hdl.rkt
diff --git a/beautiful-racket/br/demo/hdl/Not.tst b/beautiful-racket/br/demo/hdl/Not.tst.rkt
similarity index 69%
rename from beautiful-racket/br/demo/hdl/Not.tst
rename to beautiful-racket/br/demo/hdl/Not.tst.rkt
index cf9f044..3aa9734 100644
--- a/beautiful-racket/br/demo/hdl/Not.tst
+++ b/beautiful-racket/br/demo/hdl/Not.tst.rkt
@@ -1,4 +1,4 @@
-#lang br/demo/hdl/tst
+#lang br/demo/hdl-tst
 
 /* Not */
 
diff --git a/beautiful-racket/br/demo/hdl/Or.hdl b/beautiful-racket/br/demo/hdl/Or.hdl.rkt
similarity index 100%
rename from beautiful-racket/br/demo/hdl/Or.hdl
rename to beautiful-racket/br/demo/hdl/Or.hdl.rkt
diff --git a/beautiful-racket/br/demo/hdl/Or.tst b/beautiful-racket/br/demo/hdl/Or.tst.rkt
similarity index 88%
rename from beautiful-racket/br/demo/hdl/Or.tst
rename to beautiful-racket/br/demo/hdl/Or.tst.rkt
index 477b357..4dd873e 100644
--- a/beautiful-racket/br/demo/hdl/Or.tst
+++ b/beautiful-racket/br/demo/hdl/Or.tst.rkt
@@ -1,4 +1,4 @@
-#lang br/demo/hdl/tst
+#lang br/demo/hdl-tst
 
 /* or */
 
diff --git a/beautiful-racket/br/demo/hdl/Toffoli.hdl.rkt b/beautiful-racket/br/demo/hdl/Toffoli.hdl.rkt
new file mode 100644
index 0000000..b519f67
--- /dev/null
+++ b/beautiful-racket/br/demo/hdl/Toffoli.hdl.rkt
@@ -0,0 +1,13 @@
+#lang br/demo/hdl
+
+CHIP And {
+          IN a, b;
+             OUT out;
+             
+             PARTS:
+             Nand(a=a, b=b, out=nandout);
+             Not(in=nandout, out=out);
+             }
+
+
+
diff --git a/beautiful-racket/br/demo/hdl/Xor.hdl b/beautiful-racket/br/demo/hdl/Xor.hdl.rkt
similarity index 100%
rename from beautiful-racket/br/demo/hdl/Xor.hdl
rename to beautiful-racket/br/demo/hdl/Xor.hdl.rkt
diff --git a/beautiful-racket/br/demo/hdl/Xor.tst b/beautiful-racket/br/demo/hdl/Xor.tst.rkt
similarity index 88%
rename from beautiful-racket/br/demo/hdl/Xor.tst
rename to beautiful-racket/br/demo/hdl/Xor.tst.rkt
index d342aa9..b4cc445 100644
--- a/beautiful-racket/br/demo/hdl/Xor.tst
+++ b/beautiful-racket/br/demo/hdl/Xor.tst.rkt
@@ -1,4 +1,4 @@
-#lang br/demo/hdl/tst
+#lang br/demo/hdl-tst
 
 load Xor.hdl,
 output-list a, b, out;