[Coco] [COCO] MAME FDC Issue that can cause corruption

[David Ladd]

Salvador,

You can link the videos if you want, but I did not make them public so
everyone on YouTube would be able to search for them.  I just wanted to be
able to just show these to the development team and those whom do use MAME
for the CoCo for now that there is a issue and I was able to re-produce
it.  I have been able to re-produce the issue in both 32bit and 64bit
Official 0.188 Windows Binaries.


Also I found if you wait till the drive motor shuts off and do a DIR on the
other drive the directory shows up correctly.

I am currently uploading another video showing my tests in the Official
32bit Windows Binary right now so that I have documented proof it is
re-producible in both binaries.

Well I guess the video is done uploading and processing already so here is
the link for you to look at if you like:
https://youtu.be/yWdGQMb_qGU

+-----------------------------------------------------------------------+
| David Ladd a.k.a. PacoOtaktay a.k.a. Drencor                          |
| YouTube: http://www.youtube.com/user/PacoOtaktay                      |
| YouTube Gaming Live: https://gaming.youtube.com/user/PacoOtaktay/live |
| Websites: http://dwladd.com     &     http://www.theterrorzone.com    |
| G+:  https://plus.google.com/113262444659438038657                    |
| G+:  https://plus.google.com/+DavidLaddPacoOtaktay                    |
|                                                                       |
| Do you have your CoCo 3 yet?                                          |
+-----------------------------------------------------------------------+


On Tue, Aug 1, 2017 at 10:18 AM, Salvador Garcia via Coco <
coco at maltedmedia.com> wrote:

> David, I saw the videos that you posted. The video description mentions
> that it is a private, unlisted video. Does that mean that you prefer that
> we not share the video link?
>
> Also, it is clearly demonstrated that DIR 0: DIR 1 shows this issue, what
> happens when the two DIRs are on separate lines?
>
> Thanks, Salvador
>
>
>
> On Tuesday, August 1, 2017, 12:50:45 AM CDT, David Ladd <
> davidwladd at gmail.com> wrote:
>
> Dear MAME users,
>
> Over the last couple months I have been doing a LOT of disk testing and
> stuff with emulators, but is even more scary than I thought 2 months ago.
>
> I just found out tonight that MAME does indeed have a issue related to the
> FDC emulation.  I can reproduce the issue in NitrOS-9 L1/L2 or OS-9 L1/L2.
> I have even been able to re-produce some stuff in Disk Basic.
>
> Till this issue is fixed I would recommend to not use more than 1 floppy
> drive in MAME.
> If you want to try it out the simplest way to show this off is to do this:
> Startup CoCo 2 or CoCo3 emulation
> Create a new disk image in drive 0
> Create a new disk image in drive 1
> DSKINI 0
> DSKINI 1
> Enter a quick basic program like this and save it to disk:
> 10 PRINT "DIR 0"
> 20 DIR 0
> 30 PRINT "DIR 1"
> 40 DIR 1
> 50 GOTO 10
> SAVE"TEST1.BAS"
>
> Then all you have to do to see the problem is to:
> DIR 0:DIR 1
>
> You will see TEST1.BAS show up twice.  Which it should not.
>
> So please take heed that this can cause corruption if data is written to
> both drives at same time.  I found this out the hard way tonight.
>
> I am also going to clarify I am doing this just as a warning.  I am not
> trying to scare people away from MAME or say one emulator is better than
> another one.  I just want people to take heed with this issue till the
> problem has been addressed.
>
> Also the more people who can also verify this problem and report it to the
> development website for MAME might also help motivate the dev team to fix
> the issue as well.
>
> Thank you for your time with reading this.
>
> +-----------------------------------------------------------------------+
> | David Ladd a.k.a. PacoOtaktay a.k.a. Drencor                          |
> | YouTube: http://www.youtube.com/user/PacoOtaktay                     |
> | YouTube Gaming Live: https://gaming.youtube.com/user/PacoOtaktay/live |
> | Websites: http://dwladd.com     &    http://www.theterrorzone.com   |
> | G+:  https://plus.google.com/113262444659438038657                   |
> | G+:  https://plus.google.com/+DavidLaddPacoOtaktay                   |
> |                                                                      |
> | Do you have your CoCo 3 yet?                                          |
> +-----------------------------------------------------------------------+
>
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