Issues with my falcon.. data corruption.

HxC Floppy Emulator on Atari ST support
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rpineau
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Joined: Mon May 06, 2013 2:43 am

Issues with my falcon.. data corruption.

Post by rpineau » Mon May 06, 2013 8:40 am

I just tested my new HxC Floppy Drive Emulator on my Falcon and every image seems to have corrupted data.
I created the HFE image on a mac with HxCFloppyEmulator 2.0.12.2
I tested multiple ways of creating the images :
- Created a 1.44MB MSDOS disk image, mount it, copy the file to it and then convert it with HxCFloppyEmulator. Reading it on my Falcon showed some corrupted data. The .img file works in Aranym so I know it's good.
- Created a new HFE in HxCFloppyEmulator, used the Disk Browser option, added my files and did a Save/Export to a HFE file. Same result on the Falcon... corrupted data.
- Created a blank HFE, then from the Falcon did a disk format for the GEM. This worked sometimes. When it work if I copy files on it.. I get an error and then the data is corrupted.

My Falcon is ... highly modified :
- Afterburner at 20/40 MHz
- Eclipse PCI card
- Ethernec

But the floppy drive I have can read and write regular floppies so I don't think I have a DMA/FDC issue at this point.
The HxC was used in its default configuration (no CFG file to start with, then one with the HFE file interfacemode set to auto (Generic Shugart shows as grayed).

Any idea of what the problem could be ?
Thank you
Rodolphe

PS : You can reply in French or English as I speak Both... whatever is easier for you.

Jeff
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Re: Issues with my falcon.. data corruption.

Post by Jeff » Mon May 06, 2013 1:25 pm

By data corruption do you mean "read error" ? Or something else ?
Anyway update the firmware by the one present in your mail box, format an HD image and send me back the HFE file.

rpineau
Posts: 19
Joined: Mon May 06, 2013 2:43 am

Re: Issues with my falcon.. data corruption.

Post by rpineau » Mon May 06, 2013 4:23 pm

Hi Jeff,

by corruption I mean data corruption.
The directory list in the drive window has file with corrupted names and invalid size. and when I try to copy from the card to the hard drive I get GEM/TOS error as the filename are invalid and file size are invalid.
In some case the directory listing is ok but when I double click to start an application, it start loading and exit right away (usually with some bombs) as the data in the file is not correct and result in an invalid executable (and probably execute some bad code that end up doing some BRA or JMP to wrong address space or execute some invalid instruction).

I will try the new firmware , probably not before next weekend though.

Thank you
Rodolphe

Jeff
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Re: Issues with my falcon.. data corruption.

Post by Jeff » Mon May 06, 2013 9:48 pm

rpineau wrote:Hi Jeff,

by corruption I mean data corruption.
The directory list in the drive window has file with corrupted names and invalid size. and when I try to copy from the card to the hard drive I get GEM/TOS error as the filename are invalid and file size are invalid.
In some case the directory listing is ok but when I double click to start an application, it start loading and exit right away (usually with some bombs) as the data in the file is not correct and result in an invalid executable (and probably execute some bad code that end up doing some BRA or JMP to wrong address space or execute some invalid instruction).

I will try the new firmware , probably not before next weekend though.

Thank you
Rodolphe
Very very strange : By design you cannot have "data corruption" without read error : The HFE is a track copy at the pulse level. So if a data is wrong, the crc is wrong and the WD1772 report it (as a with an floppy) ...

For this can be :
-> An side signal problem (the bad side is read). (floppy cable problem?).
-> a DMA problem (can you try to disable the accelerator ?)
-> an error during the image generation. (crc are ok according to the bad data...)

Have you tried some DD images ?

Please try the new firmware.

rpineau
Posts: 19
Joined: Mon May 06, 2013 2:43 am

Re: Issues with my falcon.. data corruption.

Post by rpineau » Mon May 06, 2013 9:52 pm

Hi Jeff.

- I'm fairly sure the cable is good as it's working with a regular floppy drive.
- As for the DMA, I could try putting back a 32MHz crystal on the mother board but If I remember well, my AB040 doesn't actually work at 16/32 MHz (go figure ! ). But I'll try.
- I can generate an HFE and send you a download link if that helps.

Thanks for your help.

Rodolphe

Jeff
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Re: Issues with my falcon.. data corruption.

Post by Jeff » Mon May 06, 2013 9:53 pm

rpineau wrote:Hi Jeff.

- I'm fairly sure the cable is good as it's working with a regular floppy drive.
- As for the DMA, I could try putting back a 32MHz crystal on the mother board but If I remember well, my AB040 doesn't actually work at 16/32 MHz (go figure ! ). But I'll try.
- I can generate an HFE and send you a download link if that helps.

Thanks for your help.

Rodolphe
Can you try the new firmware ?

rpineau
Posts: 19
Joined: Mon May 06, 2013 2:43 am

Re: Issues with my falcon.. data corruption.

Post by rpineau » Mon May 06, 2013 10:00 pm

Not before this weekend.
Even though I'm French I live in USA, so right now I'm at work... no Falcon here ;)

To be more exact, I'll be able to put the firmware on the reader probably this evening, but I won't be able to plug the reader on my Falcon before this weekend as it's in a box in the garage and I don't have time during the week to install it on the kitchen table to experiment (one day I'll build a new case for it ... one day).

Regards, Rodolphe

rpineau
Posts: 19
Joined: Mon May 06, 2013 2:43 am

Re: Issues with my falcon.. data corruption.

Post by rpineau » Sun May 12, 2013 12:43 am

So I ran more tests.
I create a blank HD and blank DD floppy HFE file. Put them on a 4GB SD card (Sandisk class 10).

Falcon + AB040 at 20/40MHz : Data corruption with both the HxC and a regular floppy drive.
So clearly the HxC is not the cause of the problem here.

Falcon + AB040 at 16.5/33MHz (I don't have a 32 MHz oscillator) : no problems either with both the HxC and the regular floppy drive.

So in conclusion : No over-clocking for me ... back to 33MHz and it seems like the whole machine is more stable.
So sorry about this post (it might still be useful for other Falcon user that over-clock them).

Regards, Rodolphe

Jeff
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Re: Issues with my falcon.. data corruption.

Post by Jeff » Sun May 12, 2013 11:35 am

rpineau wrote: ...
So clearly the HxC is not the cause of the problem here
...
So in conclusion : No over-clocking for me ... back to 33MHz and it seems like the whole machine is more stable.
So sorry about this post (it might still be useful for other Falcon user that over-clock them).

Regards, Rodolphe
No problem, this is an interesting case !

Unlike some others floppy emulator designs, there is no direct conversion of the media sectors or of an "ISO" / ST images to floppy sector with the HxC floppy emulator design.

By direct conversion i mean : Read the data sector from the USB / SD sector or file, add the sector Header and compute the Header CRC & Data CRC.
If you got a none-detected problem (example : corrupted flash) during the USB/SD/ISO file reading into this kind of emulator , you may have the behavior you got :
The bad datas are loaded by the emulator, sector header is added and data CRC is computed with the bad datas, and whole thing is sent to the FDC (in MFM/FM...)
The corrupted datas are not detected by the FDC because the CRC is "OK" with these bad datas ! -> This is the worst scenario !
The system think to have good data have but the datas are wrong !
I let you think about the possible catastrophic issues this kind of "hidden" errors may lead, especially with some CNC industrials machines...

As i said by design you cannot have this issue with the HxC Floppy Emulator.
The HFE file is a track copy at the pulse level. So if a data is wrong, the CRC is wrong and the FDC will report it (as with an true floppy disk).
Since the HxC doesn't compute the CRC itself, it cannot make "corrupted" sectors with the "right" CRC value.
So with the HxC, a correctly read sector (from the FDC point of view) is for sure OK because the CRC send to the FDC is also on the SDCard !
All the data path is protected by this CRC (from the SDCard flash chip to the FDC input).

rpineau
Posts: 19
Joined: Mon May 06, 2013 2:43 am

Re: Issues with my falcon.. data corruption.

Post by rpineau » Sun May 12, 2013 4:33 pm

Thank for the explanation Jeff. Makes total sense.

Regards, Rodolphe

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