* I/O Opcode 1 - Close
*
* This routine will check to see if the file specified
* is open.  If it is, it will close it.  It does this
* by zeroing out the FDR address.  If the buffer needs
* to be written out, it will do that and write out the
* FDR.
*

CLOSE0 ANDI R12,>FF00
       AI   R12,24
       LDCR @B02,4            Select RAM bank 2
       BLWP @IFO              Check to see if file is open
       JEQ  CLOSE1

       BL   @DSRERR
       DATA >0700             File error

CLOSE1 BL   @FLUSH            Write buffer if necessary

* Here is where we clear the buffer address to mark
* the file as closed.

       LDCR @B02,4            Select RAM bank 2
       CLR  @4(R5)
       LDCR @ZERO,4
       B    @DSRRT
