Path: utzoo!attcan!uunet!van-bc!jhenders
From: jhenders@van-bc.wimsey.bc.ca (John Henders)
Newsgroups: comp.sys.atari.st
Subject: Re: Forcing a media change
Summary: FMC, steal sys vec
Keywords: MEDIA CHANGE, MOUNT
Message-ID: <812@van-bc.wimsey.bc.ca>
Date: 9 Jul 90 02:08:32 GMT
References: <204@shiloh.UUCP>
Organization: USENET Public Access, Vancouver, B.C., Canada
Lines: 27


  Re: Forcing media change.
 There is a pd autoboot program around called FMC,I believe,which will force a 
media change on your floppy drives. If you need to do this in your own program,
I did it once by stealing the vector at $47e,then using this little routine to
replace it.
my_mc:
        move.w  4(a7),d0	        * drive?        
        move.l  sys_vec,a0
        cmp.w   #$c,d0  	        		* you talking to me?
        bne     .sk1 		           * no get lost
        cmp.w   #0,dc_flg1      * copied a disk lately?
        beq     .sk2            * no then use rd vec
        move.l  #ret_err,a0     * otherwise tell tos to look again
.sk1    jmp     (a0)
.sk2    move.l  sav_vec,a0
        jmp     (a0)    
ret_err:
  	      moveq.w #2,d0           * disk has definately been changed      
        move.w  #0,dc_flg1      * only need to check once
        rts
 Note that this was written to support loading a ramdisk (M) with a floppy
as a sort of an un-Turtle program. The system would not look at a ramdisk
for a media change as I loaded the ramdisk by using the ramdisk memory as a 
track buffer.