diff --git a/bio.c b/bio.c
index 602c915..36b258e 100644
--- a/bio.c
+++ b/bio.c
@@ -42,9 +42,9 @@ bread(uint dev, uint sector)
   b = getblk();
 
   acquire(&ide_lock);
-  c = ide_start_read(dev & 0xff, sector, b->data, 1);
+  c = ide_start_rw(dev & 0xff, sector, b->data, 1, 1);
   sleep (c, &ide_lock);
-  ide_finish_read(c);
+  ide_finish(c);
   release(&ide_lock);
 
   return b;
diff --git a/defs.h b/defs.h
index fead1d2..7cf1e08 100644
--- a/defs.h
+++ b/defs.h
@@ -91,8 +91,8 @@ void fd_incref(struct fd *fd);
 // ide.c
 void ide_init(void);
 void ide_intr(void);
-void* ide_start_read(int diskno, uint secno, void *dst, uint nsecs);
-int ide_finish_read(void *);
+void* ide_start_rw(int diskno, uint secno, void *dst, uint nsecs, int read);
+int ide_finish(void *);
 
 // bio.c
 struct buf;
diff --git a/ide.c b/ide.c
index e2235a1..bfc3d7c 100644
--- a/ide.c
+++ b/ide.c
@@ -20,8 +20,9 @@
 struct ide_request {
   int diskno;
   uint secno;
-  void *dst;
+  void *addr;
   uint nsecs;
+  uint read;
 };
 struct ide_request request[NREQUEST];
 int head, tail;
@@ -93,20 +94,22 @@ ide_start_request (void)
   if (head != tail) {
     r = &request[tail];
     ide_wait_ready(0);
-    outb(0x3f6, 0);
+    outb(0x3f6, 0);  // generate interrupt
     outb(0x1F2, r->nsecs);
     outb(0x1F3, r->secno & 0xFF);
     outb(0x1F4, (r->secno >> 8) & 0xFF);
     outb(0x1F5, (r->secno >> 16) & 0xFF);
     outb(0x1F6, 0xE0 | ((r->diskno&1)<<4) | ((r->secno>>24)&0x0F));
-    outb(0x1F7, 0x20);	// CMD 0x20 means read sector
+    if (r->read) outb(0x1F7, 0x20); // read
+    else outb(0x1F7, 0x30); // write
   }
 }
 
 void *
-ide_start_read(int diskno, uint secno, void *dst, uint nsecs)
+ide_start_rw(int diskno, uint secno, void *addr, uint nsecs, int read)
 {
   struct ide_request *r;
+
   if(!holding(&ide_lock))
     panic("ide_start_read: not holding ide_lock");
 
@@ -118,9 +121,10 @@ ide_start_read(int diskno, uint secno, void *dst, uint nsecs)
 
   r = &request[head];
   r->secno = secno;
-  r->dst = dst;
+  r->addr = addr;
   r->nsecs = nsecs;
   r->diskno = diskno;
+  r->read = read;
 
   head = (head + 1) % NREQUEST;
 
@@ -130,7 +134,7 @@ ide_start_read(int diskno, uint secno, void *dst, uint nsecs)
 }
 
 int
-ide_finish_read(void *c)
+ide_finish(void *c)
 {
   int r = 0;
   struct ide_request *req = (struct ide_request *) c;
@@ -140,10 +144,11 @@ ide_finish_read(void *c)
 
   if(!holding(&ide_lock))
     panic("ide_start_read: not holding ide_lock");
-  for (; req->nsecs > 0; req->nsecs--, req->dst += 512) {
+  for (; req->nsecs > 0; req->nsecs--, req->addr += 512) {
     if ((r = ide_wait_ready(1)) < 0)
       break;
-    insl(0x1F0, req->dst, 512/4);
+    if (req->read) insl(0x1F0, req->addr, 512/4);
+    else outsl(0x1F0, req->addr, 512/4);
   }
 
   if ((head + 1) % NREQUEST == tail) {