anchor.diff:        (= x (>> x 1)))
       (write-bit o chk)))
   
  +(defun write-byte (o x)
  +  (= *chk* (bit-xor *chk* x))
  +  (write-byte-without-checksumming o x))
  +
   (defun write-leader (o)
     (format t "Making leader...~%")
  -  (adotimes #x6400
  +  (adotimes #x6a00
  +    (write-short o)))
  +
  +(defun write-sync (o repeated?)
  +  (format t "Making ~Async...~%" (? repeated? "repeated " ""))
  +  (dolist (i '(9 8 7 6 5 4 3 2 1))
  +    (write-byte o (+ (? repeated? 0 128) i))))
  +
  +(defun write-interblock-gap (o)
  +  (format t "Making interblock gap...~%")
  +  (adotimes #x4f
  +    (write-short o)))
  +
  +(defun write-interrecord-gap (o)
  +  (format t "Making interrecord gap...~%")
  +  (adotimes #x1500
       (write-short o)))
   
   (defun write-trailer (o)
  
positive.code: 
  (defun write-pulse (o len)
    (princ (code-char len) o))
  
  (defun write-short (o)
    (write-pulse o +short+))
  
negative.code: 
  (defvar *chk* 0)
  
  (defun write-byte-without-checksumming (o x)
    (write-sod o)
    (let chk 1
      (dotimes (i 8)
  