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

[Ron Klein]

The developer who reached out to me was not able to reproduce the issue
(via the BASIC example below) using MAME 0.188.  He wants to resolve it,
but needs to reproduce it.  I'll be testing this out when I get home after
work.  I know Barry was to able to confirm the issue (as of MAME 0.186).

Can anyone else please try David's BASIC example below if they have MAME
0.186 (or greater)?

I compile my own builds of MAME.  Is that what others are doing or is the
official MAME binary being used (not that it should matter, but you never
know).

Thanks!



On Tue, Aug 1, 2017 at 5:37 AM, Ron Klein <ron at kdomain.org> wrote:

> Let me clarify...
>
> I sent the developer your example below.  I want to have him try the OS-9
> example from your video, but want to know what DSK images you used.
>
> Thanks!
>
>
> On Tue, Aug 1, 2017 at 5:27 AM, Ron Klein <ron at kdomain.org> wrote:
>
>> Hi David,
>>
>> I'll get this in front of one of the MAME developers to look at.  Please
>> provide the links to the DSK images you used so the developer can reproduce
>> the exact issue you are describing.
>>
>> Thanks!
>>
>>
>> On Tue, Aug 1, 2017 at 12:50 AM, 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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>>> Coco at maltedmedia.com
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>>>
>>
>>
>