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Read Errors handling

Posted: Sun Aug 14, 2011 9:56 am
by hawui1
Hi,
I just unpacked/tested the Kryoflux device and I noticed a strange behavior.
Reading disks that can be flawlessly read on different AMIGAs I have (one is an A500, one is A1200 and one is an A600) with Kryoflux I have random read errors. These disks are original OS3.1 disks I kept like gold and very well preserved. They are DS/DD disks (presumably) created by a master machine back in the 90's and were used rarely only to install the O/S when needed. Moreover I have three floppy drives here that I used for Kryoflux testing: two are Samsung SFD-321B /LFEB Rev.T9 (brand new, never used before) and another is an old ALPS DF334H012A. Strange to say, the very old APLS is the one that produces less read errors.. one of the brand new Samsungs is reading horribly, the second one is producing anyway more read errors than the ALPS that has no less than 15 years of service.
Some of the disks in the set (composed of 6 disks) can be read entirely with no errors (2 disks) but only with the ALPS drive, the rest of disks/drive combinations are continuosly producing read errors.

What makes me particularly surprised however is that if I read the disk multiple times the very same track/surface sometimes is read correctly sometimes not.. moreover usually when you encounter an error reading a track either with DOS or with Amiga O/S you hear that typical rattling noise of the read head being moved apart and then back on track to try to read again (maybe compensating for a very slight misalignment) this doesn't happen with Kryoflux, the head stays in place and reads 4-5 times (you see this by looking at the small square changing its color in the GUI and by the absence of "pulses" noise) but then if all of the 4-5 reads fail the square become red and bye by..
Could it be that adopting the same "rattling" strategy the read capabilities could be slightly improved?

One question: is there any possibility to use an original AMIGA 880K 3,5" floppy drive with Kryoflux ?

Other question. There is a (big) molex 12V+5V connector on the board.. If I connect the small 12+5V adapter directly to the floppy power supply can I left the molex on the board unconnected and let the board be supplied only by the USB port?

Re: Read Errors handling

Posted: Sun Aug 14, 2011 6:18 pm
by mr.vince
Could be all your drives got out of alignment over the years; yes, you can for sure use an 880k Amiga drive, although we do recommend HD drives as these can usually deliver better dumps, especiall for some protections.

As for you power question: Just power the drive directly, the board can be powered by USB (see installation guide).

Re: Read Errors handling

Posted: Mon Aug 15, 2011 9:53 am
by hawui1
Could be all your drives got out of alignment over the years
that would be surprising thinking that two of them are brand-new "never used before" drives... I will buy-try another one..

regarding AMIGA drives I can connect them directly to the board as I do with the PC-HD drives?

P.S: regarding the feature of stepping some tracks away and then back over the track with a read error won't help ?

Re: Read Errors handling

Posted: Mon Aug 15, 2011 11:39 am
by IFW
Yes, that is planned.

Re: Read Errors handling

Posted: Tue Aug 16, 2011 8:29 pm
by hawui1
Sorry, but just to be 100% sure I'm not going to cook everything..
mr.vince wrote: yes, you can for sure use an 880k Amiga drive, although we do recommend HD drives as these can usually deliver better dumps, especiall for some protections.
My final question is: can i connect directly the flat cable coming from the Kryoflux that I regularly use for the PC HD 1.44Mb floppy to an AMIGA drive without damaging anything and having the 880Kb AMIGA drive work ? or a kind of signal adapter is needed?

Re: Read Errors handling

Posted: Tue Aug 16, 2011 8:54 pm
by mr.vince
No, same type of drive. Although with small changes, you won't e.g. see the light going on. It stays off...

Re: Read Errors handling

Posted: Thu Aug 18, 2011 8:07 pm
by hawui1
Regarding the issues I encountered with the previously mentioned drives.. maybe I found the source of the problems.. it is not misalignment..
I found another 3,5 floppy drive, old .. but still reasonably in good conditions.. a SAMSUNG SFD-321B /LEB T5.. this one works like charm.. reads ALL the AMIGA disks I throw at it with no flaws..
I disassembled all the drives (the latter /LEB and the previous ones) and there's only one big difference among them.. the SFD-321B /LEB that works perfectly does have the DD/HD switch that recognizes the "hole" indicating whether a disk is 1,44mb or 720Kb.. while all of the other drives (non working ones) don't.. I strongly suspect that 3,5" floppy drives missing the physical density switch (on the left looking at the "mouth" opening of the drive) are not capable to correctly read the old DS/DD 720Kb (or 880Kb for Amiga) disks.. they're good only for 1,44Mb medias (and in fact the non working drives mentioned above read beautifully these kind of PC formatted disks but not the AMIGA formatted disks that are DS/DD). Note that the SFD-321B that are not working with AMIGA disks (even if I bought them brand new some weeks ago) are marked as /LFEB and they miss the density switch.. while the working one I found lately is marked as /LEB and does have it..

What's your thought?

Re: Read Errors handling

Posted: Fri Aug 19, 2011 9:37 am
by IFW
You do need the drive hardware to support dd disks, there is no work around as it requires different hardware. In other words you are spot on :-)

Re: Read Errors handling

Posted: Fri Aug 19, 2011 8:49 pm
by hawui1
The only issue is that the vast majority of the new 3.5" units you find on the market since 10Years (and more) are 1.44 Mb only.. and they don't have the density switch..
I would be curios to know if anybody that has one of these drives were able to make it work with the AMIGA 880Kb disks..

I don't know if these drives missing the density switch are anyway conserving the electrical features needed to cope with 720Kb disks.. could it be there's a kind of jumper on the PCB to activate the 720Kb mode?

Re: Read Errors handling

Posted: Sat Aug 20, 2011 12:09 pm
by IFW
Repositioning the head after a read error is now working, will be in the next DTC release.