diff --git a/Makefile.in b/Makefile.in
index 779e2a0..5dd65a5 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -225,7 +225,6 @@ scsh/network1o:	  scsh/network1.h
 scsh/flock1.o:	   scsh/flock1.h
 
 scsh/fdports1.o	  scsh/fdports.o:  scsh/fdports1.h
-#scsh/select1.o	  scsh/select.o:   scsh/select1.h
 
 scsh/rx/regexp1.o:    c/scheme48.h
 
@@ -436,9 +435,6 @@ clean: clean-cig clean-scsh
 clean-cig:
 	-rm -f cig/*.o $(CIG) $(CIG).image $(LIBCIG)
 
-clean-scm2c:
-	rm -f #scsh/select.c
-
 distclean: clean
 	rm -f Makefile config.log config.status c/sysdep.h config.cache \
 		scsh/machine \
@@ -841,7 +837,6 @@ SCHEME =scsh/awk.scm \
 # Explicitly giving the .o/.c dependency also makes it go.
 ############################################################
 cig/libcig.c:		cig/libcig.scm
-#scsh/select.c:	    	scsh/select.scm
 
 scsh/scsh: scsh/scsh-tramp.c
 	$(CC) -o $@ $(CPPFLAGS) $(CFLAGS) \
diff --git a/c/event.h b/c/event.h
index 96874e5..b2548b6 100644
--- a/c/event.h
+++ b/c/event.h
@@ -1,5 +1,7 @@
-enum event_enum { KEYBOARD_INTERRUPT_EVENT, IO_COMPLETION_EVENT, ALARM_EVENT,
-		    OS_SIGNAL_EVENT, ERROR_EVENT, NO_EVENT };
+enum event_enum { KEYBOARD_INTERRUPT_EVENT,
+		  IO_READ_COMPLETION_EVENT, IO_WRITE_COMPLETION_EVENT,
+		  ALARM_EVENT,
+		  OS_SIGNAL_EVENT, ERROR_EVENT, NO_EVENT };
 
 extern bool s48_add_pending_fd(int fd, bool is_input);
 extern bool s48_remove_fd(int fd);
diff --git a/c/unix/event.c b/c/unix/event.c
index 99379a9..428a1a1 100644
--- a/c/unix/event.c
+++ b/c/unix/event.c
@@ -287,7 +287,7 @@ s48_stop_alarm_interrupts(void)
  *                  (queue-ready-ports)
  *                  (set! *poll-time* (+ *time* *poll-interval*))))
  *           (cond ((not (queue-empty? ready-ports))
- *                  (values (enum event-type i/o-completion)
+ *                  (values (enum event-type i/o-{read/write}-completion)
  *                          (dequeue! ready-ports)))
  *                 ((>= *current_time* *alarm-time*)
  *                  (set! *alarm-time* max-integer)
@@ -302,9 +302,20 @@ s48_stop_alarm_interrupts(void)
  *                  (values (enum event-type no-event) #f))))))
  */
 
-static bool	there_are_ready_ports(void);
-static int	next_ready_port(void);
-static int	queue_ready_ports(bool wait, long seconds, long ticks);
+#define FD_QUIESCENT 0			/* idle */
+#define FD_READY     1			/* I/O ready to be performed */
+#define FD_PENDING   2			/* waiting */
+
+typedef struct fd_struct {
+ int	fd,			/* file descriptor */
+	status;			/* one of the FD_* constants */
+ bool	is_input;		/* iff input */
+ struct fd_struct	*next;	/* next on same queue */
+} fd_struct;
+
+static bool	 there_are_ready_ports(void);
+static fd_struct *next_ready_fd_struct(void);
+static int	 queue_ready_ports(bool wait, long seconds, long ticks);
 
 int
 s48_get_next_event(long *ready_fd, long *status)
@@ -314,6 +325,8 @@ s48_get_next_event(long *ready_fd, long *status)
   */
 
   int io_poll_status;
+  fd_struct *f;
+
   /*
     fprintf(stderr, "[poll at %d (waiting for %d)]\n", s48_current_time, alarm_time);
     */
@@ -334,10 +347,14 @@ s48_get_next_event(long *ready_fd, long *status)
     }
   }
   if (there_are_ready_ports()) {
-    *ready_fd = next_ready_port();
+    f = next_ready_fd_struct();
+    *ready_fd = f->fd;
     *status = 0;   /* chars read or written */
     /* fprintf(stderr, "[i/o completion]\n"); */
-    return (IO_COMPLETION_EVENT);
+    if (f->is_input)
+      return (IO_READ_COMPLETION_EVENT);
+    else
+      return (IO_WRITE_COMPLETION_EVENT);
   }
   if (alarm_time != -1 && s48_current_time >= alarm_time) {
     alarm_time = -1;
@@ -364,17 +381,6 @@ s48_get_next_event(long *ready_fd, long *status)
  * the pending ports and move any that are ready onto the other queue and
  * signal an event.
  */
-#define FD_QUIESCENT 0			/* idle */
-#define FD_READY     1			/* I/O ready to be performed */
-#define FD_PENDING   2			/* waiting */
-
-typedef struct fd_struct {
- int	fd,			/* file descriptor */
-	status;			/* one of the FD_* constants */
- bool	is_input;		/* iff input */
- struct fd_struct	*next;	/* next on same queue */
-} fd_struct;
-
 
 /*
  * A queue of fd_structs is empty iff the first field is NULL.  In
@@ -459,14 +465,14 @@ there_are_ready_ports(void)
 }
 
 
-static int
-next_ready_port(void)
+static fd_struct *
+next_ready_fd_struct(void)
 {
   fd_struct	*p;
 
   p = rmque(&ready.first, &ready);
   p->status = FD_QUIESCENT;
-  return (p->fd);
+  return (p);
 }
 
 
diff --git a/c/unix/fd-io.c b/c/unix/fd-io.c
index 5f3ba3d..22c8083 100644
--- a/c/unix/fd-io.c
+++ b/c/unix/fd-io.c
@@ -111,6 +111,16 @@ bool ps_check_fd(long fd_as_long, bool is_read, long *status)
 	return FALSE; } } 
 }
 
+/*
+ * Return TRUE if successful, and FALSE otherwise.
+ */
+
+bool
+ps_add_pending_fd(long fd_as_long, bool is_input)
+{
+  return s48_add_pending_fd((int) fd_as_long, is_input);
+}
+
 long
 ps_read_fd(long fd_as_long, char *buffer, long max, bool waitp,
 	   bool *eofp, bool *pending, long *status)
@@ -201,7 +211,7 @@ long
 ps_abort_fd_op(long fd_as_long)
 {
   int fd = (int)fd_as_long;
-
+  fprintf(stderr, "aborting %d\n", fd);
   if (!s48_remove_fd(fd))
     fprintf(stderr, "Error: ps_abort_fd_op, no pending operation on fd %d\n",
 	            fd);
diff --git a/c/unix/socket.c b/c/unix/socket.c
index 2896c50..7acca9e 100644
--- a/c/unix/socket.c
+++ b/c/unix/socket.c
@@ -36,9 +36,23 @@ static s48_value	s48_socket(s48_value server_p),
 					      s48_value input_p),
 			s48_get_host_name(void);
 
+s48_value s48_add_pending_channel (s48_value channel)
+{
+  int socket_fd;
+
+  S48_CHECK_CHANNEL(channel);
+  socket_fd = S48_UNSAFE_EXTRACT_FIXNUM(S48_UNSAFE_CHANNEL_OS_INDEX(channel));
+
+  if (! s48_add_pending_fd(socket_fd, 1)) // 1 for: yes, is input 
+    s48_raise_out_of_memory_error();
+
+  return S48_UNSPECIFIC;
+}
+
 /*
  * Install all exported functions in Scheme48.
  */
+
 void
 s48_init_socket(void)
 {
@@ -50,6 +64,7 @@ s48_init_socket(void)
   S48_EXPORT_FUNCTION(s48_connect);
   S48_EXPORT_FUNCTION(s48_close_socket_half);
   S48_EXPORT_FUNCTION(s48_get_host_name);
+  S48_EXPORT_FUNCTION(s48_add_pending_channel);
 }
 
 /*
diff --git a/scheme/interfaces.scm b/scheme/interfaces.scm
index 125f08f..c334e54 100644
--- a/scheme/interfaces.scm
+++ b/scheme/interfaces.scm
@@ -54,6 +54,7 @@
 
 (define-interface primitives-interface
   (export add-finalizer!
+	  add-pending-channel
 	  call-external-value
 	  checked-record-ref
 	  checked-record-set!
@@ -544,6 +545,7 @@
 	  output-channel+closer->port	;big/socket.scm
 	  
 	  ; call WAIT-FOR-CHANNEL with interrupts disabled
+	  wait-for-channels
 	  wait-for-channel		;big/socket.scm
 
 	  port->channel			;posix
@@ -584,6 +586,7 @@
 	  
 	  block
 	  make-ready
+	  set-thread-cell! clear-thread-cell!
 	  spawn-on-scheduler spawn-on-root
 	  wait
 	  upcall propogate-upcall
@@ -592,6 +595,7 @@
 	  terminate-thread!
 
 	  wake-some-threads
+	  register-dozer
 
 	  all-threads                   ; for command-levels
 
diff --git a/scheme/rts-packages.scm b/scheme/rts-packages.scm
index 2edfa8e..4fb954d 100644
--- a/scheme/rts-packages.scm
+++ b/scheme/rts-packages.scm
@@ -101,7 +101,7 @@
 	channels low-channels
 	architecture code-vectors wind
 	define-record-types
-	queues threads threads-internal locks
+	queues threads threads-internal locks cells
 	exceptions interrupts
 	ascii ports util
 	session-data
diff --git a/scheme/rts/channel-io.scm b/scheme/rts/channel-io.scm
index 81a8dcd..77bce3b 100644
--- a/scheme/rts/channel-io.scm
+++ b/scheme/rts/channel-io.scm
@@ -2,33 +2,54 @@
 
 ; Channel interrupt stuff.
 
-; Install an interrupt handler that queues up the results of completed I/O
+; Install an interrupt handler that cells up the results of completed I/O
 ; operations and spawn a thread to cope with them.  This is written so as
 ; to avoid having state in top-level variables, because their values are
 ; saved in dumped images.
 
 (define (initialize-channel-i/o!)
-  (session-data-set! channel-wait-queues-slot '())
+  (session-data-set! channel-wait-cells-slot '())
   (session-data-set! channel-wait-count-slot 0)
-  (set-interrupt-handler! (enum interrupt i/o-completion)
-			  i/o-completion-handler))
+  (set-interrupt-handler! (enum interrupt i/o-read-completion)
+			  (make-i/o-completion-handler
+			   (lambda (cell channel)
+			     (let ((old (cell-ref cell)))
+			       (cell-set! cell
+					  (cons (cons channel (car old))
+						(cdr old)))))))
+  (set-interrupt-handler! (enum interrupt i/o-write-completion)
+			  (make-i/o-completion-handler
+			   (make-i/o-completion-handler
+			    (lambda (cell channel)
+			      (let ((old (cell-ref cell)))
+				(cell-set! cell
+					   (cons (car old)
+						 (cons channel (cdr old))))))))))
 
 ; The warning message is printed using DEBUG-MESSAGE because to try to make
 ; sure it appears in spite of whatever problem's the I/O system is having.
-;
-; Called with interrupts disabled.
 
-(define (i/o-completion-handler channel status enabled-interrupts)
-  (let ((queue (fetch-channel-wait-queue! channel)))
-    (if queue
-	(begin
-	  (decrement-channel-wait-count!)
-	  (make-ready (maybe-dequeue-thread! queue) status))
-	(debug-message "Warning: dropping ignored channel i/o result {Channel "
-		       (channel-os-index channel)
-		       " "
-		       (channel-id channel)
-		       "}"))))
+(define (make-i/o-completion-handler update-ready-cell)
+  ;; Called with interrupts disabled.
+  (lambda (channel status enabled-interrupts)
+    (call-with-values
+     (lambda () (fetch-channel-wait-cell! channel))
+     (lambda (thread-cell maybe-ready-cell)
+       (cond
+	((and thread-cell (cell-ref thread-cell))
+	 => (lambda (thread)
+	      (decrement-channel-wait-count!)
+	      (make-ready thread status)))
+	(else
+	 (debug-message "Warning: dropping ignored channel i/o result {Channel "
+			(channel-os-index channel)
+			" "
+			(channel-id channel)
+			"}")))
+       (cond
+	((and maybe-ready-cell
+	      (cell-ref maybe-ready-cell))
+	 (update-ready-cell maybe-ready-cell channel)))))))
 
 ; Exported procedure
 
@@ -44,46 +65,114 @@
 ; terminated.
 
 (define (wait-for-channel channel)
-  (let ((queue (fetch-channel-wait-queue! channel)))
-    (if queue
-	(begin
-	  (add-channel-wait-queue! channel queue)
-	  (warn "channel has two pending operations" channel)
-	  (terminate-current-thread))
-	(let ((queue (make-queue)))
-	  (increment-channel-wait-count!)
-	  (enqueue-thread! queue (current-thread))
-	  (add-channel-wait-queue! channel queue)
-	  (dynamic-wind nothing
-			block
-			(lambda ()
-			  (disable-interrupts!)
-			  (let ((new-queue (fetch-channel-wait-queue! channel)))
-			    (cond ((eq? queue new-queue)
-				   (channel-abort channel)
-				   (wait-for-channel channel))
-				  (new-queue
-				   (add-channel-wait-queue! channel new-queue)))
-			    (enable-interrupts!))))))))
+  (call-with-values
+   (lambda () (fetch-channel-wait-cell! channel))
+   (lambda (thread-cell maybe-ready-cell)
+     (if (and thread-cell (cell-ref thread-cell))
+	 (begin
+	   (add-channel-wait-cell! channel thread-cell #f)
+	   (warn "channel has two pending operations" channel)
+	   (terminate-current-thread))
+	 (let ((cell (make-cell (current-thread))))
+	   (increment-channel-wait-count!)
+	   (set-thread-cell! (current-thread) cell)
+	   (add-channel-wait-cell! channel cell #f)
+	   (dynamic-wind nothing
+			 block
+			 (lambda ()
+			   (disable-interrupts!)
+			   (if (cell-ref cell)
+			       ;; we're being terminated
+			       (begin
+				 (fetch-channel-wait-cell! channel)
+				 (channel-abort channel)
+				 (wait-for-channel channel)))
+			   (enable-interrupts!))))))))
 
 (define (nothing) #f)
 
+(define (channel-check-waiter channel)
+  (if (channel-has-waiter? channel)
+      (begin
+	(warn "channel has two pending operations" channel)
+	(terminate-current-thread))))
+
+(define (wait-for-channels read-channels write-channels timeout)
+  ;; check if we're borked from the outset
+  (for-each channel-has-waiter? read-channels)
+  (for-each channel-has-waiter? write-channels)
+
+  (let ((thread-cell (make-cell (current-thread)))
+	(ready-channels-cell (make-cell (cons '() '())))
+	(ready-read-channels #f)
+	(ready-write-channels #f))
+
+    (if (or (not timeout)
+	    (register-dozer thread-cell timeout))
+	(begin
+	  ;; register us with every channel we're waiting for
+	  (set-thread-cell! (current-thread) thread-cell)
+	  (let ((signup (lambda (channel)
+			  (add-channel-wait-cell! channel
+						  thread-cell ready-channels-cell)
+			  (increment-channel-wait-count!))))
+	    (for-each signup read-channels)
+	    (for-each signup write-channels))
+
+	  ;; block
+	  (dynamic-wind
+	   nothing
+	   (lambda ()
+	     (block)
+	     (disable-interrupts!)
+	     (let ((pair (cell-ref ready-channels-cell)))
+	       (set! ready-read-channels (car pair))
+	       (set! ready-write-channels (cdr pair)))
+	     (cell-set! ready-channels-cell #f)
+	     (enable-interrupts!)
+	     (values ready-read-channels ready-write-channels))
+	   ;; clean up
+	   (lambda ()
+	     (let ((aborting? (and (cell-ref thread-cell) #t)))
+	       (disable-interrupts!)
+	       ;; this ain't so great ...
+	       (let ((make-cleanup
+		      (lambda (ready-channels)
+			(lambda (channel)
+			  (if (memq channel ready-channels)
+			      (begin
+				(fetch-channel-wait-cell! channel)
+				(if (not aborting?)
+				    (decrement-channel-wait-count!)
+				    (begin
+				      (channel-abort channel)
+				      (wait-for-channel channel)))))))))
+		 (for-each (make-cleanup ready-read-channels) read-channels)
+		 (for-each (make-cleanup ready-write-channels) write-channels))
+
+	       (enable-interrupts!)))))
+	;; the timeout was zero or less
+	(enable-interrupts!))))
+
 ; Abort any pending operation on by OWNER on CHANNEL.
 ; Called with interrupts disabled.
   
 (define (steal-channel! channel owner)
-  (let ((queue (fetch-channel-wait-queue! channel)))
-    (if queue
-	(let ((thread (maybe-dequeue-thread! queue)))
-	  (cond ((eq? thread owner)
-		 (decrement-channel-wait-count!)
-                 (channel-abort channel))
-		(else
-		 (warn "channel in use by other than port owner" 
-		       channel thread owner)
-		 (enqueue-thread! queue thread)
-		 #f)))
-	#f)))
+  (call-with-values
+   (lambda () (fetch-channel-wait-cell! channel))
+   (lambda (thread-cell maybe-ready-cell)
+     (cond
+      ((cell-ref thread-cell)
+       => (lambda (thread)
+	    (cond ((eq? thread owner)
+		   (clear-thread-cell! thread)
+		   (decrement-channel-wait-count!)
+		   (channel-abort channel))
+		  (else
+		   (warn "channel in use by other than port owner" 
+			 channel thread owner)
+		   #f))))
+      (else #f)))))
 
 ; Have CHANNEL-READ and CHANNEL-WRITE wait if a pending-channel-i/o
 ; exception occurs.
@@ -110,7 +199,7 @@
 
 ; Two session slots
 ;   - the number of threads waiting for I/O completion events
-;   - an alist mapping channels to queues for waiting threads
+;   - an alist mapping channels to cells for waiting threads
 
 (define channel-wait-count-slot (make-session-data-slot! 0))
 
@@ -123,40 +212,47 @@
 (define (decrement-channel-wait-count!)
   (session-data-set! channel-wait-count-slot (- (channel-wait-count) 1)))
 
-(define channel-wait-queues-slot (make-session-data-slot! '()))
+(define channel-wait-cells-slot (make-session-data-slot! '()))
 
-; Adding a queue and channel - the caller has already determined there is no
-; existing queue for this channel.
+; Adding a cell and channel - the caller has already determined there is no
+; existing cell for this channel.
 
-(define (add-channel-wait-queue! channel queue)
-  (session-data-set! channel-wait-queues-slot
-		     (cons (cons channel queue)
-			   (session-data-ref channel-wait-queues-slot))))
+(define (add-channel-wait-cell! channel cell maybe-ready-channels-cell)
+  (session-data-set! channel-wait-cells-slot
+		     (cons (cons channel (cons cell maybe-ready-channels-cell))
+			   (session-data-ref channel-wait-cells-slot))))
 
 ; This is just deleting from an a-list.
 
-(define (fetch-channel-wait-queue! channel)
-  (let* ((queues (session-data-ref channel-wait-queues-slot))
-	 (queue (cond ((null? queues)
-		       #f)
-		      ((eq? channel (caar queues))
-		       (session-data-set! channel-wait-queues-slot
-					  (cdr queues))
-		       (cdar queues))
-		      (else
-		       (let loop ((queues (cdr queues)) (prev queues))
-			 (cond ((null? queues)
-				#f)
-			       ((eq? channel (caar queues))
-				(set-cdr! prev (cdr queues))
-				(cdar queues))
-			       (else
-				(loop (cdr queues) queues))))))))
-    (if (or (not queue)
-	    (thread-queue-empty? queue))
-	#f
-	queue)))
-      
-  
+(define (fetch-channel-wait-cell! channel)
+  (let* ((cells (session-data-ref channel-wait-cells-slot))
+	 (cell+ready-channels-cell
+	  (cond ((null? cells)
+		 #f)
+		((eq? channel (caar cells))
+		 (session-data-set! channel-wait-cells-slot
+				    (cdr cells))
+		 (cdar cells))
+		(else
+		 (let loop ((cells (cdr cells)) (prev cells))
+		   (cond ((null? cells)
+			  #f)
+			 ((eq? channel (caar cells))
+			  (set-cdr! prev (cdr cells))
+			  (cdar cells))
+			 (else
+			  (loop (cdr cells) cells))))))))
+    (cond
+     (cell+ready-channels-cell
+      => (lambda (pair)
+	   (let ((thread-cell (car pair))
+		 (ready-cell (cdr pair)))
+	     (values thread-cell ready-cell))))
+     (else
+      (values #f #f)))))
+
+(define (channel-has-waiter? channel)
+  (and (assq channel 
+	     (session-data-ref channel-wait-cells-slot))
+       #t))
 
-  
diff --git a/scheme/rts/sleep.scm b/scheme/rts/sleep.scm
index c954ba2..5970ed7 100644
--- a/scheme/rts/sleep.scm
+++ b/scheme/rts/sleep.scm
@@ -10,14 +10,26 @@
 	   (let ((cell (make-cell (current-thread))))
 	     (disable-interrupts!)
 	     (set-thread-cell! (current-thread) cell)
-	     (set! *dozers*
-		   (insert (cons (+ (real-time) n)
-				 cell)
-			   *dozers*
-			   (lambda (frob1 frob2)
-			     (< (car frob1) (car frob2)))))
+	     (insert-dozer! cell n)
 	     (block))))))
 
+(define (register-dozer cell user-n)
+  (let ((n (coerce-to-nonnegative-integer user-n)))
+    (cond ((not n)
+	   (call-error "wrong type argument" sleep user-n))
+	  ((< 0 n)
+	   (insert-dozer! cell n)
+	   #t)
+	  (else #f))))
+
+(define (insert-dozer! cell n) 
+  (set! *dozers*
+	(insert (cons (+ (real-time) n)
+		      cell)
+		*dozers*
+		(lambda (frob1 frob2)
+		  (< (car frob1) (car frob2))))))
+
 (define (coerce-to-nonnegative-integer n)
   (if (real? n)
       (let* ((n (round n))
diff --git a/scheme/vm/arch.scm b/scheme/vm/arch.scm
index fe9fbe8..68ef52f 100644
--- a/scheme/vm/arch.scm
+++ b/scheme/vm/arch.scm
@@ -183,6 +183,7 @@
   (close-channel 1)
   (channel-maybe-read 5)
   (channel-maybe-write 4)
+  (add-pending-channel 2)
   (channel-ready? 1)
   (channel-abort 1)             ; stop channel operation
   (open-channels-list)		; return a list of the open channels
@@ -240,7 +241,8 @@
   (alarm           ; order matters - higher priority first
    keyboard
    post-gc         ; handler is passed a list of finalizers
-   i/o-completion  ; handler is passed channel and status
+   i/o-read-completion  ; handler is passed channel and status
+   i/o-write-completion  ; handler is passed channel and status
    os-signal       
    ))
 
diff --git a/scheme/vm/interfaces.scm b/scheme/vm/interfaces.scm
index 2d96f48..0f69338 100644
--- a/scheme/vm/interfaces.scm
+++ b/scheme/vm/interfaces.scm
@@ -405,6 +405,7 @@
 	  channel-read-block
 	  channel-write-block
 	  channel-abort
+	  add-pending-channel
 	  ))
 
 (define external-call-interface
diff --git a/scheme/vm/interrupt.scm b/scheme/vm/interrupt.scm
index 4bf1856..b066cdc 100644
--- a/scheme/vm/interrupt.scm
+++ b/scheme/vm/interrupt.scm
@@ -45,7 +45,7 @@
 ; For alarm interrupts the interrupted template is passed to the handler
 ;  for use by code profilers.
 ; For gc interrupts we push the list of things to be finalized.
-; For i/o-completion we push the channel and its status.
+; For i/o-{read,write}-completion we push the channel and its status.
 
 (define (push-interrupt-args pending-interrupt)
   (cond ((eq? pending-interrupt (enum interrupt alarm))
@@ -58,10 +58,11 @@
 	 (set! *finalize-these* null)
 	 (push (enter-fixnum *enabled-interrupts*))
 	 2)
-	((eq? pending-interrupt (enum interrupt i/o-completion))
+	((or (eq? pending-interrupt (enum interrupt i/o-read-completion))
+	     (eq? pending-interrupt (enum interrupt i/o-write-completion)))
 	 (let ((channel (dequeue-channel!)))
 	   (if (not (channel-queue-empty?))
-	       (note-interrupt! (enum interrupt i/o-completion)))
+	       (note-interrupt! pending-interrupt))
 	   (push channel)
 	   (push (channel-os-status channel))
 	   (push (enter-fixnum *enabled-interrupts*))
@@ -232,9 +233,12 @@
 	 (interrupt-bit (enum interrupt alarm)))
 	((eq? event (enum events keyboard-interrupt-event))
 	 (interrupt-bit (enum interrupt keyboard)))
-	((eq? event (enum events io-completion-event))
+	((eq? event (enum events io-read-completion-event))
 	 (enqueue-channel! channel status)
-	 (interrupt-bit (enum interrupt i/o-completion)))
+	 (interrupt-bit (enum interrupt i/o-read-completion)))
+	((eq? event (enum events io-write-completion-event))
+	 (enqueue-channel! channel status)
+	 (interrupt-bit (enum interrupt i/o-write-completion)))
 	((eq? event (enum events os-signal-event))
 	 (interrupt-bit (enum interrupt os-signal)))
 	((eq? event (enum events no-event))
diff --git a/scheme/vm/prim-io.scm b/scheme/vm/prim-io.scm
index 3e225fb..c65cd19 100644
--- a/scheme/vm/prim-io.scm
+++ b/scheme/vm/prim-io.scm
@@ -190,6 +190,11 @@
     (lambda (buffer start count channel key)
       (do-it buffer start count #f channel key))))
 
+(define-primitive add-pending-channel (channel-> boolean->)
+  (lambda (channel input?)
+   (add-pending-channel (extract-channel channel) input?))
+  return-boolean)
+
 (define-primitive channel-abort (channel->)
   (lambda (channel)
     (goto return (vm-channel-abort channel))))
diff --git a/scheme/vm/ps-channel.scm b/scheme/vm/ps-channel.scm
index 4050375..8f6d871 100644
--- a/scheme/vm/ps-channel.scm
+++ b/scheme/vm/ps-channel.scm
@@ -64,7 +64,7 @@
 ; PENDING? - true if the operation cannot complete immediately
 ; STATUS - from an enumeration defined as part of Pre-Scheme
 ;
-; Pending i/o operations produce i/o-completion events when they're done.
+; Pending i/o operations produce i/o-{read,write}-completion events when they're done.
 
 (define channel-read-block
   (external "ps_read_fd"
@@ -77,6 +77,11 @@
 (define channel-abort
   (external "ps_abort_fd_op" (=> (integer) integer)))
 
+; Checking a channel for data
+
+(define add-pending-channel
+  (external "ps_add_pending_fd" (=> (integer boolean) boolean)))
+
 ;----------------------------------------------------------------
 ; Asynchronous external events
 
@@ -84,7 +89,8 @@
 
 (define-external-enumeration events
   (keyboard-interrupt-event     ; user interrupt
-   io-completion-event          ; a pending i/o operation completed
+   io-read-completion-event	; a pending read operation completed
+   io-write-completion-event	; a pending write operation completed
    alarm-event                  ; scheduled interrupt
    os-signal-event		; some OS signal of no interest to the VM occured
    error-event                  ; OS error occurred
@@ -101,9 +107,10 @@
 (define pending-event?
   (external "pending_eventp" (=> () boolean)))
 
-; Returns the next event.  The second return value is the FD for i/o-completion
-; events and the third is the status for i/o-completion and error events.
-; (currently this is always zero for i/o-completions).
+; Returns the next event.  The second return value is the FD for
+; i/o-{read,write}-completion events and the third is the status for
+; i/o-{read,write}-completion and error events.  (currently this is
+; always zero for i/o-{read,write}-completions).
 
 (define get-next-event
   (external "s48_get_next_event" (=> () integer integer integer)))
diff --git a/scheme/vm/s48-channel.scm b/scheme/vm/s48-channel.scm
index 143a873..6833207 100644
--- a/scheme/vm/s48-channel.scm
+++ b/scheme/vm/s48-channel.scm
@@ -130,7 +130,8 @@
 
 (define-enumeration events
   (keyboard-interrupt-event
-   io-completion-event
+   io-read-completion-event
+   io-write-completion-event
    alarm-event
    os-signal-event
    error-event
diff --git a/scheme/vm/vmio.scm b/scheme/vm/vmio.scm
index 4c8a2bf..34f9358 100644
--- a/scheme/vm/vmio.scm
+++ b/scheme/vm/vmio.scm
@@ -210,7 +210,7 @@
 	 res))))
 
 ;----------------------------------------------------------------
-; Handling i/o-completion interrupts
+; Handling i/o-{read,write}-completion interrupts
 ; Currently, because the GC may move buffers, strings, etc. around, the OS
 ; must buffer the data while waiting for i/o to complete.
 ;
diff --git a/scsh/newports.scm b/scsh/newports.scm
index 986275a..0776c34 100644
--- a/scsh/newports.scm
+++ b/scsh/newports.scm
@@ -730,4 +730,179 @@
 
 ;;; replace rts/channel-port.scm end
 	  
-    
\ No newline at end of file
+;;; select
+;;; -----
+
+(define (port/fdes->port port/fd)
+  (if (port? port/fd)
+      port/fd
+      (fdes->inport port/fd))) ; ####
+
+(define (port/fdes-ready? port/fd)
+  (let ((port (port/fdes->port port/fd)))
+    ((port-handler-ready? (port-handler port)) port)))
+
+(define (any-ready port/fds)
+  (let loop ((port/fds port/fds))
+    (if (null? port/fds)
+	'()
+	(let ((port/fd (car port/fds)))
+	    (if (port/fdes-ready? port/fd)
+		;; one is ready, get them all
+		(let loop ((rest (cdr port/fds))
+			   (ready (list port/fd)))
+		  (cond
+		   ((null? rest) (reverse ready))
+		   ((port/fdes-ready? (car rest))
+		    (loop (cdr rest) (cons (car rest) ready)))
+		   (else
+		    (loop (cdr rest) ready))))
+		(loop (cdr port/fds)))))))
+
+(define (port/fdes-check-unlocked port/fd)
+  (if (port-locked? (port/fdes->port port/fd))
+      (begin
+	((structure-ref interrupts enable-interrupts!))
+	(error "SELECT on port with pending operation"
+	       port/fd))))
+
+(define (port/fdes->channel port/fd)
+  (fdport-data:channel
+   (fdport-data
+    (port/fdes->port port/fd))))
+
+;; this is way too epic and probably should just be split up once the
+;; dust has settled ---Mike
+
+(define (make-select !?)
+  (lambda (read-vec write-vec exception-vec . maybe-timeout)
+    (let ((read-list (vector->list read-vec))
+	  (write-list (vector->list write-vec)))
+
+      ((structure-ref interrupts disable-interrupts!))
+    
+      (for-each port/fdes-check-unlocked read-list)
+      (for-each port/fdes-check-unlocked write-list)
+
+      (let ((any-read (any-ready read-list))
+	    (any-write (any-ready write-list)))
+	(if (or (pair? any-read) (pair? any-write))
+	    (begin
+	      ((structure-ref interrupts enable-interrupts!))
+	      (if !?			; we're SELECT!
+		  (let ((n-read-ready
+			 (let ((length (vector-length read-vec)))
+			   (let loop ((i 0) (n 0))
+			     (cond
+			      ((= i length) n)
+			      ((memq (vector-ref read-vec i) any-read)
+			       (loop (+ 1 i) (+ 1 n)))
+			      (else
+			       (vector-set! read-vec i #f)
+			       (loop (+ 1 i) n))))))
+			(n-write-ready
+			 (let ((length (vector-length write-vec)))
+			   (let loop ((i 0) (n 0))
+			     (cond
+			      ((= i length) n)
+			      ((memq (vector-ref write-vec i) any-write)
+			       (loop (+ 1 i) (+ 1 n)))
+			      (else
+			       (vector-set! write-vec i #f)
+			       (loop (+ 1 i) n)))))))
+		  
+		    ;; zero out EXCEPTION-VEC
+		    (let ((length (vector-length exception-vec)))
+		      (let loop ((i 0))
+			(if (< i length)
+			    (begin
+			      (vector-set! exception-vec i #f)
+			      (loop (+ 1 i))))))
+			  
+		    (values n-read-ready n-write-ready 0))
+		  ;; we're vanilla SELECT
+		  (values (list->vector any-read)
+			  (list->vector any-write)
+			  (make-vector 0))))
+	    
+	    ;; we need to block
+	    (let ((read-channels (map port/fdes->channel read-list))
+		  (write-channels (map port/fdes->channel write-list)))
+
+	      (for-each (lambda (channel)
+			  (add-pending-channel channel #t))
+			read-channels)
+
+	      (for-each (lambda (channel)
+			  (add-pending-channel channel #f))
+			write-channels)
+	
+	      (call-with-values
+	       (lambda ()
+		 (apply wait-for-channels read-channels write-channels maybe-timeout))
+	       ;; re-enables interrupts
+	       (lambda (ready-read-channels ready-write-channels)
+
+		 ;; too many free variables ...
+		 (if !?			; we're SELECT!
+		     (let ((n-read-ready
+			    (let loop ((read-channels read-channels)
+				       (n-ready 0)
+				       (index 0))
+			      (if (null? read-channels)
+				  n-ready
+				  (if (memq (car read-channels) ready-read-channels)
+				      (loop (cdr read-channels)
+					    (+ 1 n-ready)
+					    (+ 1 index))
+				      (begin
+					(vector-set! read-vec index #f)
+					(loop (cdr read-channels)
+					      n-ready
+					      (+ 1 index)))))))
+			   (n-write-ready 
+			    (let loop ((write-channels write-channels)
+				       (n-ready 0)
+				       (index 0))
+			      (if (null? write-channels)
+				  n-ready
+				  (if (memq (car write-channels) ready-write-channels)
+				      (loop (cdr write-channels)
+					    (+ 1 n-ready)
+					    (+ 1 index))
+				      (begin
+					(vector-set! write-vec index #f)
+					(loop (cdr write-channels)
+					      n-ready
+					      (+ 1 index))))))))
+		       ;; zero out EXCEPTION-VEC
+		       (let ((length (vector-length exception-vec)))
+			 (let loop ((i 0))
+			   (if (< i length)
+			       (begin
+				 (vector-set! exception-vec i #f)
+				 (loop (+ 1 i))))))
+
+		       (values n-read-ready n-write-ready 0))
+
+		     ;; we're vanilla SELECT
+		     (let ((ready-read-port/fds '())
+			   (ready-write-port/fds '()))
+		       (for-each (lambda (port/fd channel)
+				   (if (memq channel ready-read-channels)
+				       (set! ready-read-port/fds
+					     (cons port/fd ready-read-port/fds))))
+				 read-list read-channels)
+		       (for-each (lambda (port/fd channel)
+				   (if (memq channel ready-write-channels)
+				       (set! ready-write-port/fds
+					     (cons port/fd ready-write-port/fds))))
+				 write-list write-channels)
+
+		       (values (list->vector (reverse ready-read-port/fds))
+			       (list->vector (reverse ready-write-port/fds))
+			       (make-vector 0))))))))))))
+
+(define select (make-select #f))
+
+(define select! (make-select #t))
diff --git a/scsh/scsh-interfaces.scm b/scsh/scsh-interfaces.scm
index 9f5a0b8..46e74d8 100644
--- a/scsh/scsh-interfaces.scm
+++ b/scsh/scsh-interfaces.scm
@@ -222,6 +222,9 @@
 			      read-string!
 			      read-string/partial
 			      read-string!/partial
+
+			      select select!
+
 			      (write-string (proc (:string &opt :value :exact-integer :exact-integer) :unspecific))
 			      write-string/partial)))
 
diff --git a/scsh/select.c b/scsh/select.c
deleted file mode 100644
index 22d06f4..0000000
--- a/scsh/select.c
+++ /dev/null
@@ -1,61 +0,0 @@
-/* This is an Scheme48/C interface file, 
-** automatically generated by a hacked version of cig 3.0.
-step 4
-*/
-
-#include <stdio.h>
-#include <stdlib.h> /* For malloc. */
-#include "libcig.h"
-
-/* Make sure foreign-function stubs interface to the C funs correctly: */
-#include "select1.h"
-
-s48_value df_select_copyback(s48_value g1, s48_value g2, s48_value g3, s48_value g4, s48_value mv_vec)
-{
-    extern s48_value select_copyback(s48_value , s48_value , s48_value , s48_value , int *, int *, int *);
-    s48_value ret1 = S48_FALSE;
-    S48_DECLARE_GC_PROTECT(2);
-    s48_value r1;
-    int r2 = 0;
-    int r3 = 0;
-    int r4 = 0;
-
-    
-    
-    S48_GC_PROTECT_2(mv_vec,ret1);
-    r1 = select_copyback(g1, g2, g3, g4, &r2, &r3, &r4);
-    ret1 = r1;
-    S48_VECTOR_SET(mv_vec,0,s48_enter_fixnum(r2));
-    S48_VECTOR_SET(mv_vec,1,s48_enter_fixnum(r3));
-    S48_VECTOR_SET(mv_vec,2,s48_enter_fixnum(r4));
-    S48_GC_UNPROTECT();
-    return ret1;
-}
-
-s48_value df_select_filter(s48_value g1, s48_value g2, s48_value g3, s48_value g4, s48_value mv_vec)
-{
-    extern s48_value select_filter(s48_value , s48_value , s48_value , s48_value , int *, int *, int *);
-    s48_value ret1 = S48_FALSE;
-    S48_DECLARE_GC_PROTECT(2);
-    s48_value r1;
-    int r2 = 0;
-    int r3 = 0;
-    int r4 = 0;
-
-    
-    
-    S48_GC_PROTECT_2(mv_vec,ret1);
-    r1 = select_filter(g1, g2, g3, g4, &r2, &r3, &r4);
-    ret1 = r1;
-    S48_VECTOR_SET(mv_vec,0,s48_enter_fixnum(r2));
-    S48_VECTOR_SET(mv_vec,1,s48_enter_fixnum(r3));
-    S48_VECTOR_SET(mv_vec,2,s48_enter_fixnum(r4));
-    S48_GC_UNPROTECT();
-    return ret1;
-}
-
-void s48_init_select(void)
-{
-    S48_EXPORT_FUNCTION(df_select_copyback);
-    S48_EXPORT_FUNCTION(df_select_filter);
-}
diff --git a/scsh/select.scm b/scsh/select.scm
deleted file mode 100644
index ee53fb6..0000000
--- a/scsh/select.scm
+++ /dev/null
@@ -1,193 +0,0 @@
-;;; select(2) syscall for scsh. -*- Scheme -*-
-;;; Copyright (c) 1995 by Olin Shivers.
-
-(foreign-init-name "select")
-
-
-(foreign-source
-  "/* Make sure foreign-function stubs interface to the C funs correctly: */"
-  "#include \"select1.h\""
-  "" "")
-
-;;; TIMEOUT is 0 for immediate, >0 for timeout, #f for infinite; 
-;;;     default is #f.
-;;; The sets are vectors of file descriptors & fd ports.
-;;; You get three new vectors back.
-
-; The following routines copy ports to fd's, and copy fd's back to fd's and
-; ports, so that select can take numbers and ports, simultaneously.
-
-; This is a C procedure in scheme.  So sue me.  At least it's tail-recursive
-(define (fd-filter filter-me)
-  (let* ((len (vector-length filter-me))
-	 (vector-to-return (make-vector len)))
-    (let loop ((count (- len 1)))
-      (if (>= count 0)
-	  (let ((ref (vector-ref filter-me count)))
-	    (if (integer? ref)
-		(vector-set! vector-to-return count ref)
-		(vector-set! vector-to-return count (port->fdes ref)))
-	    (loop (- count 1)))))
-    vector-to-return))
-
-; ! means side-effect, the next one is more functional.
-(define (fd-copyback! orig form)
-  (let loop ((count (- (vector-length orig) 1)))
-    (if (>= count 0)
-	(begin
-	  (if (not (vector-ref form count))
-	      (vector-set! orig count #f)
-	      (vector-set! form count (vector-ref orig count)))
-	  (loop (- count 1)))))
-  orig)
-
-(define (fd-copyback orig form)
-  (let* ((len (vector-length orig))
-	 (vector-to-return (make-vector len #f)))
-    (let loop ((count (- len 1)))
-      (if (>= count 0)
-	  (begin
-	    (if (vector-ref form count)
-		(vector-set! vector-to-return count (vector-ref orig count)))
-	    (loop (- count 1)))))
-    vector-to-return))
-    
-(define (select read-vec write-vec exception-vec . maybe-timeout)
-  (let ((rv (copy-vector read-vec))
-	(wv (copy-vector write-vec))
-	(ev (copy-vector exception-vec)))
-    (receive (nr nw ne) (apply select! rv wv ev maybe-timeout)
-      (values (vector-take-form read-vec rv nr)
-	      (vector-take-form write-vec wv nw)
-	      (vector-take-form exception-vec ev ne)))))
-
-
-(define (select!/copyback read-vec write-vec exception-vec . maybe-timeout)
-  (receive (errno nr nw ne)
-           (apply select!/copyback/errno read-vec write-vec exception-vec
-		                         maybe-timeout)
-     (if errno
-	 (apply errno-error errno select!/copyback
-		read-vec write-vec exception-vec maybe-timeout)
-	 (values nr nw ne))))
-
-
-(define (select!/copyback/errno read-vec write-vec
-				exception-vec . maybe-timeout)
-  (let ((timeout (and (pair? maybe-timeout)
-		      (if (pair? (cdr maybe-timeout))
-			  (apply error "Too many arguments"
-				 select!/copyback/errno
-				 read-vec write-vec exception-vec
-				 maybe-timeout)
-			  (real->exact-integer (check-arg real?
-							  (car maybe-timeout)
-							  select!/copyback/errno)))))
-		     
-	(vec-ok? (lambda (v)
-		   (vector-every? (lambda (elt)
-				    (or (and (integer? elt) (>= elt 0))
-					(fdport? elt)))
-				  v))))
-    ;; Type-check input vectors.
-    (check-arg vec-ok?      read-vec select!/copyback/errno)
-    (check-arg vec-ok?     write-vec select!/copyback/errno)
-    (check-arg vec-ok? exception-vec select!/copyback/errno)
-    (check-arg (lambda (x) (or (not x) (integer? x))) timeout
-	       select!/copyback/errno)
-
-    (let ((prop-read-vec (fd-filter read-vec))
-	  (prop-write-vec (fd-filter write-vec))
-	  (prop-exception-vec (fd-filter exception-vec)))
-      (let lp ()
-	(receive (errno nr nw ne)
-		 (%select/copyback/errno prop-read-vec prop-write-vec prop-exception-vec timeout)
-  	  (if (and errno (= errno errno/intr))	; Retry on interrupts.
-	      (lp)
-	      (values errno 
-		      (fd-copyback read-vec nr)
-		      (fd-copyback write-vec nw)
-		      (fd-copyback exception-vec ne))))))))
-
-
-(define-foreign %select/copyback/errno
-  (select_copyback (vector-desc rvec)
-		   (vector-desc wvec)
-		   (vector-desc evec)
-		   (desc nsecs))	; Integer or #f for infinity.
-  desc		; errno or #f
-  fixnum	; nread   - number of hits in RVEC
-  fixnum	; nwrite  - number of hits in WVEC
-  fixnum)	; nexcept - number of hits in EVEC
-
-
-(define (vector-take-form vec form nelts)
-  (let ((short (make-vector nelts)))
-    (do ((i (- (vector-length vec) 1) (- i 1)))
-	((< i 0))
-      (if (vector-ref form i)
-	  (begin
-	    (set! nelts (- nelts 1))
-	    (vector-set! short nelts (vector-ref vec i)))))
-    short))
-
-
-;;; SELECT!
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;;; The side-effecting variant. To be documented.
-
-(define (select! read-vec write-vec exception-vec . maybe-timeout)
-  (receive (errno nr nw ne)
-           (apply select!/errno read-vec write-vec exception-vec maybe-timeout)
-     (if errno
-	 (apply errno-error errno select! read-vec write-vec exception-vec
-		maybe-timeout)
-	 (values nr nw ne))))
-
-(define (select!/errno read-vec write-vec exception-vec . maybe-timeout)
-  (let ((timeout (and (pair? maybe-timeout)
-		      (if (pair? (cdr maybe-timeout))
-			  (apply error "Too many arguments"
-				 select!/copyback/errno
-				 read-vec write-vec exception-vec
-				 maybe-timeout)
-			  (real->exact-integer (check-arg real?
-							  (car maybe-timeout)
-							  select!/copyback/errno)))))
-		     
-	(vec-ok? (lambda (v)
-		   (vector-every? (lambda (elt)
-				    (or (and (integer? elt) (>= elt 0))
-					(not elt)
-					(fdport? elt)))
-				  v))))
-    ;; Type-check input vectors.
-    (check-arg vec-ok?      read-vec select!/errno)
-    (check-arg vec-ok?     write-vec select!/errno)
-    (check-arg vec-ok? exception-vec select!/errno)
-    (check-arg (lambda (x) (or (not x) (integer? x))) timeout select!/errno)
-	
-    (let ((prop-read-vec (fd-filter read-vec))
-	  (prop-write-vec (fd-filter write-vec))
-	  (prop-exception-vec (fd-filter exception-vec)))
-      (let lp ()
-	(receive (errno nr nw ne)
-		 (%select!/errno prop-read-vec prop-write-vec prop-exception-vec timeout)
-  	  (if (and errno (= errno errno/intr))	; Retry on interrupts.
-	      (lp)
-	      (begin
-		(fd-copyback! read-vec prop-read-vec)
-		(fd-copyback! write-vec prop-write-vec)
-		(fd-copyback! exception-vec prop-exception-vec)
-		(values errno nr nw ne))))))))
-
-
-(define-foreign %select!/errno
-  (select_filter (vector-desc rvec)
-		 (vector-desc wvec)
-		 (vector-desc evec)
-		 (desc nsecs))		; Integer or #f for infinity.
-  desc		; errno or #f
-  fixnum	; nread   - number of hits in RVEC
-  fixnum	; nwrite  - number of hits in WVEC
-  fixnum)	; nexcept - number of hits in EVEC
diff --git a/scsh/select1.c b/scsh/select1.c
deleted file mode 100644
index 984af8e..0000000
--- a/scsh/select1.c
+++ /dev/null
@@ -1,223 +0,0 @@
-/* C support for scsh select call.
-** Copyright (c) 1995 by Olin Shivers.
-*/
-
-#include "sysdep.h"
-
-#include <sys/types.h>
-#if defined(HAVE_SYS_SELECT_H)
-#  include <sys/select.h>
-#endif
-#include <sys/time.h>
-
-#include <errno.h>
-#include <stdio.h>
-
-#include "cstuff.h"
-#include "fdports.h"	/* Accessors for Scheme I/O port internals. */
-
-/* Make sure our exports match up w/the implementation: */
-#include "select1.h"
-
-/* the traditional sleazy max non-function. */
-#define max(a,b) (((a) > (b)) ? (a) : (b))
-
-extern int errno;
-
-static void or2_fdset(fd_set *x, fd_set *y, int max_elt);
-static int copyback_fdvec(s48_value portvec, fd_set *fdset);
-
-/* RVEC, WVEC, and EVEC are Scheme vectors of integer file descriptors,
-** I/O ports, and #f's. NSECS is an integer timeout value, or #f for
-** infinite wait. Do the select() call, returning result fd_sets in the
-** passed pointers. Return 0 for OK, otherwise error is in errno.
-*/
-
-int do_select(s48_value rvec, s48_value wvec,
-	      s48_value evec, s48_value nsecs,
-	      fd_set *rset_ans, fd_set *wset_ans, fd_set *eset_ans)
-{
-    struct timeval timeout, *tptr;
-    fd_set rset_bufrdy, wset_bufrdy, eset_bufrdy;    /* Buffered port hits. */
-    int rbuf_rdy=0, wbuf_rdy=0, bufrdy;	/* Set if we find buffered I/O hits. */
-    int max_fd = -1;			/* Max fdes in the sets. */
-    int nelts, i;
-    int nfound;
-
-    FD_ZERO(rset_ans);		FD_ZERO(wset_ans);	FD_ZERO(eset_ans);
-    FD_ZERO(&rset_bufrdy);	FD_ZERO(&wset_bufrdy);	FD_ZERO(&eset_bufrdy);
-
-    /* Scan the readvec elts. */
-    nelts = S48_VECTOR_LENGTH(rvec);
-    for(i=nelts; --i >= 0; ) {
-	s48_value elt = S48_VECTOR_REF(rvec,i);
-	int fd;
-
-	fd = s48_extract_fixnum(elt);
-	FD_SET(fd, rset_ans);
-
-	max_fd = max(max_fd, fd);
-	}
-
-    /* Scan the writevec elts. */
-    nelts = S48_VECTOR_LENGTH(wvec);
-    for(i=nelts; --i >= 0; ) {
-	s48_value elt = S48_VECTOR_REF(wvec,i);
-	int fd;
-
-	fd = s48_extract_fixnum(elt);
-	FD_SET(fd, wset_ans);
-
-	max_fd = max(max_fd, fd);
-	}
-
-    /* Scan the exception-vec elts. */
-    nelts = S48_VECTOR_LENGTH(evec);
-    for(i=nelts; --i >= 0; ) {
-	s48_value elt = S48_VECTOR_REF(evec,i);
-	int fd;
-
-	fd = s48_extract_fixnum(elt);
-	FD_SET(fd, eset_ans);
-
-	max_fd = max(max_fd, fd);
-	}
-
-    bufrdy = rbuf_rdy || wbuf_rdy;
-    if( bufrdy ) {		/* Already have some hits on buffered ports, */
-	timeout.tv_sec = 0;	/* so we only poll the others.               */
-	timeout.tv_usec = 0;
-	tptr = &timeout;
-	}
-    else if ( S48_FIXNUM_P(nsecs) ) {
-	timeout.tv_sec = s48_extract_fixnum(nsecs);	/* Wait n seconds. */
-	timeout.tv_usec = 0;
-	tptr = &timeout;
-	}
-    else tptr = NULL;				/* #f => Infinite wait. */
-
-    /* select1() is defined in sysdep.h -- bogus compatibility macro. */
-    nfound = select(max_fd+1, rset_ans, wset_ans, eset_ans, tptr); /* Do it.*/
-
-    /* EINTR is not an error return if we have hits on buffered ports
-    ** to report.
-    */
-    if( nfound < 0 )
-	if ( errno != EINTR || !bufrdy ) return -1;
-	else {	/* EINTR, but we have hits on buffered ports to report.  */
-	    FD_ZERO(rset_ans);		/* This should never happen --   */
-	    FD_ZERO(wset_ans);		/* EINTR on a zero-sec select()  */
-	    FD_ZERO(eset_ans);		/* -- but I'm paranoid.          */
-	    }
-
-    /* OR together the buffered-io ready sets and the fd ready sets. */
-    if( rbuf_rdy ) or2_fdset(rset_ans, &rset_bufrdy, max_fd);
-    if( wbuf_rdy ) or2_fdset(wset_ans, &wset_bufrdy, max_fd);
-
-    return 0;
-    }
-
-
-
-/* x = x or y */
-static void or2_fdset(fd_set *x, fd_set *y, int max_elt)
-{
-    int i;
-    for(i=max_elt+1; --i >= 0;)
-	if( FD_ISSET(i,y) ) FD_SET(i,x);
-    }
-
-
-
-/* PORTVEC is a vector of integer file descriptors and Scheme ports.
-** Scan over the vector, and copy any elt whose file descriptor is in FDSET
-** to the front of the vector. Return the number of elts thus copied.
-*/
-static int copyback_fdvec(s48_value portvec, fd_set *fdset)
-{
-    int vlen = S48_VECTOR_LENGTH(portvec);
-    int i, j=0;
-    for( i = -1; ++i < vlen; ) {
-	s48_value elt = S48_VECTOR_REF(portvec, i);
-	int fd = s48_extract_fixnum((S48_FIXNUM_P(elt)) ? elt : (1 / 0));
-	/* JMG *PortFd(elt));*/
-	if( FD_ISSET(fd,fdset) ) {
-	    FD_CLR(fd,fdset);	/* In case luser put elt in multiple times. */
-	    S48_VECTOR_SET(portvec, j, elt);
-	    j++;
-	    }
-	}
-    return j;
-    }
-
-
-/* Overwrite every inactive element in the vector with #f;
-** Return count of active elements.
-*/
-
-static int clobber_inactives(s48_value portvec, fd_set *fdset)
-{
-    int count = 0;
-    int i = S48_VECTOR_LENGTH(portvec);
-
-    while( --i >= 0 ) {
-	s48_value elt = S48_VECTOR_REF(portvec, i);
-	if( elt != S48_FALSE ) {
-	  int fd = s48_extract_fixnum((S48_FIXNUM_P(elt)) ? elt : (1/0)); /* JMG *PortFd(elt));*/
-	    if( FD_ISSET(fd,fdset) ) {
-		FD_CLR(fd,fdset); /* In case luser put elt in multiple times. */
-		++count;
-		}
-	    else S48_VECTOR_SET(portvec, i, S48_FALSE); /* Clobber. */
-	    }
-	}
-    return count;
-    }
-
-
-/* These two functions are the entry points to this file.
-*********************************************************
-*/
-
-/* Copy active elts back to the front of their vector;
-** Return error indicator & number of hits for each vector.
-*/
-
-s48_value select_copyback(s48_value rvec, s48_value wvec,
-			     s48_value evec, s48_value nsecs,
-			     int *r_numrdy, int *w_numrdy, int *e_numrdy)
-{
-    fd_set rset, wset, eset;
-
-    if( do_select(rvec, wvec, evec, nsecs, &rset, &wset, &eset) ) {
-	*r_numrdy = *w_numrdy = *e_numrdy = 0;
-	return s48_enter_fixnum(errno);
-	}
-    
-    *r_numrdy = copyback_fdvec(rvec, &rset);
-    *w_numrdy = copyback_fdvec(wvec, &wset);
-    *e_numrdy = copyback_fdvec(evec, &eset);
-    return S48_FALSE;
-    }
-
-
-/* Overwrite non-active elements in the vectors with #f;
-** return error indicator & number of hits for each vector.
-*/
-
-s48_value select_filter(s48_value rvec, s48_value wvec,
-			   s48_value evec, s48_value nsecs,
-			   int *r_numrdy, int *w_numrdy, int *e_numrdy)
-{
-    fd_set rset, wset, eset;
-
-    if( do_select(rvec, wvec, evec, nsecs, &rset, &wset, &eset) ) {
-	*r_numrdy = *w_numrdy = *e_numrdy = 0;
-	return s48_enter_fixnum(errno);
-	}
-    
-    *r_numrdy = clobber_inactives(rvec, &rset);
-    *w_numrdy = clobber_inactives(wvec, &wset);
-    *e_numrdy = clobber_inactives(evec, &eset);
-    return S48_FALSE;
-    }
diff --git a/scsh/select1.h b/scsh/select1.h
deleted file mode 100644
index 1a91028..0000000
--- a/scsh/select1.h
+++ /dev/null
@@ -1,9 +0,0 @@
-/* Exports from select1.c. */
-
-s48_value select_copyback(s48_value rvec, s48_value wvec,
-			     s48_value evec, s48_value nsecs,
-			     int *r_numrdy, int *w_numrdy, int *e_numrdy);
-
-s48_value select_filter(s48_value rvec, s48_value wvec,
-			   s48_value evec, s48_value nsecs,
-			   int *r_numrdy, int *w_numrdy, int *e_numrdy);