Re: [hatari-devel] Re: Hatari floppy drive detection with EmuTOS

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Le 16/01/2014 18:28, Roger Burrows a écrit :
On 16 Jan 2014 at 10:46, Nicolas Pomarède wrote:

Do you have the possibility to test this on a real ST :
   - connect drive A and disconnect drive B as above
   - but in the drive detection test, test drive B first, then drive A..

I'd like to know the delay you get in that case where spinup is made
first on the disconnected drive.

I'll do that as soon as I've finished testing my current EmuTOS update.  Today
if things go well :-).

For reference, this is what TOS 1.04 does :

D6 is the command to execute (0x03 in that case)

$fc153e : 3029 0002                            move.w    2(a1),d0
$fc1542 : c03c 0003                            and.b     #3,d0
$fc1546 : 8c00                                 or.b      d0,d6
$fc1548 : 2e3c 0004 0000                       move.l    #$40000,d7
$fc154e : 3cbc 0080                            move.w    #$80,(a6)
$fc1552 : 6100 00d2                            bsr       $fc1626
$fc1556 : 0800 0007                            btst      #7,d0
$fc155a : 6606                                 bne.s     $fc1562
$fc155c : 2e3c 0006 0000                       move.l    #$60000,d7
$fc1562 : 6100 00a4                            bsr       $fc1608
$fc1566 : 5387                                 subq.l    #1,d7
$fc1568 : 6712                                 beq.s     $fc157c
$fc156a : 0839 0005 ffff fa01                  btst      #5,$fffffa01
$fc1572 : 66f2                                 bne.s     $fc1566
$fc1574 : 6100 00a6                            bsr       $fc161c
$fc1578 : 4246                                 clr.w     d6
$fc157a : 4e75                                 rts

timeout_reached_no_drive :
$fc157c : 6104                                 bsr.s     $fc1582
$fc157e : 7c01                                 moveq     #1,d6
$fc1580 : 4e75                                 rts

send_force_int :
$fc1582 : 3cbc 0080                            move.w    #$80,(a6)
$fc1586 : 3e3c 00d0                            move.w    #$d0,d7
$fc158a : 6100 0086                            bsr       $fc1612
$fc158e : 3e3c 000f                            move.w    #$f,d7
$fc1592 : 51cf fffe                            dbra      d7,$fc1592
$fc1596 : 6100 0084                            bsr       $fc161c
$fc159a : 4e75                                 rts

write_command_d6 :
$fc1608 : 6124                                 bsr.s     $fc162e
$fc160a : 33c6 ffff 8604                       move.w    d6,$ffff8604
$fc1610 : 601c                                 bra.s     $fc162e

$fc1612 : 611a                                 bsr.s     $fc162e
$fc1614 : 33c7 ffff 8604                       move.w    d7,$ffff8604
$fc161a : 6012                                 bra.s     $fc162e

$fc161c : 6110                                 bsr.s     $fc162e
$fc161e : 3e39 ffff 8604                       move.w    $ffff8604,d7
$fc1624 : 6008                                 bra.s     $fc162e

$fc1626 : 6106                                 bsr.s     $fc162e
$fc1628 : 3039 ffff 8604                       move.w    $ffff8604,d0

$fc162e : 40e7                                 move      sr,-(sp)
$fc1630 : 3f07                                 move.w    d7,-(sp)
$fc1632 : 3e3c 0020                            move.w    #$20,d7
$fc1636 : 51cf fffe                            dbra      d7,$fc1636
$fc163a : 3e1f                                 move.w    (sp)+,d7
$fc163c : 46df                                 move      (sp)+,sr
$fc163e : 4e75                                 rts

The TOS check if motor is already ON in status reg and use $60000 or $40000 as a timeout counter depending on the result.

Then it sends command 0x03 and check whether command completes first (OK, return d6=0) or timeout expires first (FAIL, return d6=1 and send force int command).

P.S. I will also test with the "disable spin up" bit set in restore, since I
agree that makes sense.  If detection is not made worse, I'll update EmuTOS
subsequently with that change.

It can only be faster and should work to detect if the head is moving and if a drive is available. But it will not detect if the motor works or not, which could happen on a semi damaged drive (but you need an inserted floppy for this anyway)

For me, the best would be for real HW :

Test a restore without spinup, then a seek to another track ; if it works (TR00 on in 1st case, and off in the 2nd case), then the drive is connected, and the head is moving correctly. You could have a damaged drive/cable that always report TR00, so it's important to test the signal is changing on track==0 and track!=0 (this is what normal tos does, but with spinup).
If this test fails, mark the drive as disconnect.

I don't really see the point of using spinup during the test, because spinup will fail anyway if there's no floppy in the drive or if the drive is disconnected (well, that's my understanding of the doc, for now we see Emutos expects different on real HW as seen in your test).

So, spinup doesn't really bring any extra useful information, just an extra delay.


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