diff --git a/scsh/rw.scm b/scsh/rw.scm
index d784c9b..667622e 100644
--- a/scsh/rw.scm
+++ b/scsh/rw.scm
@@ -33,15 +33,17 @@
     (cond ((integer? fd/port)
            (generic-read-string!/partial s start end
                                          read-fdes-substring!/errno fd/port))
-          ((fdport? fd/port)
-           (generic-read-string!/partial s start end
-                                         read-fdes-substring!/errno 
-                                         (fdport-data:fd (port-data fd/port))))
-          (else ; Hack it for base S48 ports
-	   (generic-read-string!/partial s start end
-					 read-fdes-substring!/errno
-					 (channel-os-index
-					  (port-data fd/port)))))))
+          (else ; no differnce between fd/ports and s48 ports
+	   (let* ((buffer (make-string (- end start)))
+		  (needed (if (> (byte-vector-length (port-buffer fd/port)) 1)
+			      'any 'immediate))   ;bufpol/none may return with 0
+		  (len (read-block buffer 0 needed fd/port)))
+	     (if (eof-object? len)
+		 #f
+		 (begin 
+		   (copy-bytes! buffer 0 s start len)
+		   len)))))))
+
 
 (define (read-string/partial len . maybe-fd/port) 
   (let* ((s (make-string len))
@@ -54,6 +56,8 @@
 
 ;;; Persistent reading
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;
+;;; Operation on ports is easy, since we can use read-block
 
 (define (generic-read-string! s start end reader source)
   (if (bogus-substring-spec? s start end)
@@ -81,16 +85,11 @@
 	   (generic-read-string! s start end
 				 read-fdes-substring!/errno fd/port))
 
-	  ((fdport? fd/port)
-	   (generic-read-string! s start end
-				 read-fdes-substring!/errno
-				 (fdport-data:fd (port-data fd/port))))
-
-	  ;; Hack it
-	  (else
-	   (generic-read-string! s start end
-				 read-fdes-substring!/errno
-				 (channel-os-index (port-data fd/port)))))))
+	  (else ; no differnce between fd/port and s48 ports
+	   (let ((nbytes/eof (read-block s start (- end start) fd/port)))
+	     (if (eof-object? nbytes/eof)
+		 #f
+		 nbytes/eof))))))
 
 (define (read-string len . maybe-fd/port) 
   (let* ((s (make-string len))
@@ -125,12 +124,11 @@
     (cond ((integer? fd/port)
 	   (generic-write-string/partial s start end
 					 write-fdes-substring/errno fd/port))
-	  ((fdport? fd/port)
-	   (generic-write-string/partial s start end
-					 write-fdes-substring/errno
-					 (fdport-data:fd
-					  (port-data fd/port))))
-	  (else (display (substring s start end) fd/port))))) ; hack
+	  (else 
+	   ;; the only way to implement this, would be to use 
+	   ;; channel-maybe-write. But this is an VM-instruction which is not
+	   ;; exported. Since we now have threads this shouldn;t matter.
+	   (error "write-string/parital is no longer supported on ports")))))
 
 
 ;;; Persistent writing
@@ -155,9 +153,4 @@
     (cond ((integer? fd/port)
 	   (generic-write-string s start end
 				 write-fdes-substring/errno fd/port))
-	  ((fdport? fd/port)
-	   (generic-write-string s start end
-				 write-fdes-substring/errno
-				 (fdport-data:fd (port-data fd/port))))
-
-	  (else (display (substring s start end) fd/port))))) ; hack
+	  (else (write-block s start (- end start) fd/port)))))