diff --git a/src/polio.s b/src/polio.s
index ec2e4bf..87d7bc5 100644
--- a/src/polio.s
+++ b/src/polio.s
@@ -40,20 +40,6 @@ dosdbt:                    # assumes es=0
 
     .section .text.int80stuff
 
-# near copy [param 2] bytes, ds:[param 0] -> ds:[param 1]
-copy:
-    mov ax, [bp-14]     # ds
-    mov es, ax
-    mov ds, ax
-    mov cl, 4
-    shl si, cl
-    mov si, [bp+0]      # source
-    mov di, [bp+2]      # destination
-    mov cx, [bp+4]      # length
-    cld
-    rep movsb
-    ret
-
 ## floppy stuff
 
 # same as read but with a different int13h:ah value
@@ -122,8 +108,19 @@ readfile:
     add ax, si
     mov dx, [bp+2]
     add dx, si
-    call fat12_readfile
-    ret
+    jmp fat12_readfile
+
+# params: ds:fname, ds:src, size
+writefile:
+    mov si, [bp-14] # ds
+    mov cl, 4
+    shl si, cl
+    mov ax, [bp+0]
+    add ax, si
+    mov dx, [bp+2]
+    add dx, si
+    mov cx, [bp+4]
+    jmp fat12_writefile
 
 # params: ds:addr, size
 sendpara:
@@ -133,8 +130,7 @@ sendpara:
     mov ax, [bp+0]
     add ax, si
     mov dx, [bp+2]
-    call parasend
-    ret
+    jmp parasend
 
 # params: ds:addr, size
 recvpara:
@@ -144,7 +140,10 @@ recvpara:
     mov ax, [bp+0]
     add ax, si
     mov dx, [bp+2]
-    call pararecv
+    jmp pararecv
+
+dummy:
+    mov ax, -1
     ret
 
     .section .text.int80h
@@ -155,6 +154,7 @@ int80h:
     push bp
     push ds
     push es
+    mov bp, sp
     xor cx, cx
     mov es, cx
     mov ds, cx
@@ -163,7 +163,6 @@ int80h:
     cmp cl, offset int80h_entries
     jge 0f
     mov si, cx
-    mov bp, sp
     add bp, 16       # 10 for us, 6 for the interrupt
     call cs:[int80h_table+si]
     jmp 1f
@@ -179,7 +178,7 @@ int80h:
 
     .section .rodata.int80h
 int80h_table:
-    .word offset copy           # 0x00
+    .word offset dummy          # 0x00
     .word offset readsector     # 0x01
     .word offset writesector    # 0x02
     .word offset formattrack    # 0x03
@@ -187,5 +186,6 @@ int80h_table:
     .word offset recvpara       # 0x05
     .word offset sendpara       # 0x06
     .word offset xferpara       # 0x07
+    .word offset writefile      # 0x08
 
 int80h_entries = . - int80h_table