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2.88 Mb floppy support?

Posted: Sun Jun 19, 2011 11:55 pm
by kreutz
Is there support for 2.88 Mb floppy drives/media? It would be nice if I could save images of the MF-2ED floppies I have. Thank you for the great work!!

Re: 2.88 Mb floppy support?

Posted: Mon Jun 20, 2011 9:53 pm
by mr.vince
Not with the current revision. USB bandwidth is limited with the CPU used on the KF Board, which means 2.88 can't be streamed in real time. Given the fact that these disks never were commercially replicated (=no software available on them), there are no disks that are protected with some kind of on-disk protection. Therefore you can just just an ordinary FDC to access data stored on them. A future revision of KF might incorporate a different processor with a faster USB.

Re: 2.88 Mb floppy support?

Posted: Mon Jun 20, 2011 10:26 pm
by prowler
kreutz wrote:Is there support for 2.88 Mb floppy drives/media? It would be nice if I could save images of the MF-2ED floppies I have. Thank you for the great work!!
Hi kreuz,
Do you have a PC-compatible ED floppy drive, or is it an IBM PS/2 drive. I have a pack of 10 new ED floppy disks and a PS/2 2.88MB floppy drive, and I'm looking for a way of interfacing it with my PC. I'm just wondering whether you have done that or not.

Re: 2.88 Mb floppy support?

Posted: Tue Jun 21, 2011 2:25 am
by kreutz
Do you have a PC-compatible ED floppy drive, or is it an IBM PS/2 drive. I have a pack of 10 new ED floppy disks and a PS/2 2.88MB floppy drive, and I'm looking for a way of interfacing it with my PC. I'm just wondering whether you have done that or not.
No, the 2.88Mb floppies I have came from an old (1995) industrial equipment running iRMX86. I can't read them with a normal floppy drive (I haven't tried a USB drive yet on my PC). Since they are used for troubleshooting and the vendor does not provide them anymore I am interested into saving their content for possible emulation.

Best regards,

kreutz

Re: 2.88 Mb floppy support?

Posted: Wed Jun 22, 2011 10:39 pm
by prowler
I'm sure that you won't be able to read them in any PC HD floppy drive. The problem is that the density sensing hole on the IBM 2.88MB ED floppies I have is about 6mm nearer the shutter, so that they are simply detected as 720KB DD floppies when inserted in a 1.44MB floppy drive.

The IBM PS/2 2.88MB floppy drive is able to read 720KB, 1.44MB and 2.88MB floppies by virtue of an extra sensing switch which aligns with the ED sense hole. The combination of signals from the HD and ED sensing switches puts the drive into the correct mode.

PC BIOS ROMs from about 1997 had support for 2.88MB disks and drives, and three Pentium 200MMX Tyan motherboards I have of that vintage will support them.

The problem you have is that even with this support you will still require a dumping utility which understands the disk format.

If I understand it correctly, the Catwaesel floppy controllers from Individual Computers support dumping standard PC DOS-formatted 2.88MB floppies, but no other format on these media.

PS. The drive I have is one of these:
http://www.recycledgoods.com/products/I ... X6101.html

Re: 2.88 Mb floppy support?

Posted: Thu Jun 23, 2011 1:21 am
by kreutz
Hi Prowler;
Thanks for the info, I will try to get a real 2.88Mb drive and try again.

Best regards,

kreutz

Re: 2.88 Mb floppy support?

Posted: Thu Jun 23, 2011 11:36 am
by mr.vince
I am pretty confident that 1.44 drives have a bandpass that will filter out the speedy reversals found on a 2.88MB disk...

Re: 2.88 Mb floppy support?

Posted: Fri Jun 24, 2011 12:24 am
by prowler
kreutz wrote:Hi Prowler;
Thanks for the info, I will try to get a real 2.88Mb drive and try again.
Best regards,
kreutz
Hi kreutz,
Good luck with that.
If you manage to get one, you might find the information on these pages useful in interfacing it with the floppy controller of your PC:
http://www.dslreports.com/forum/remark,6949611
http://www.tavi.co.uk/ps2pages/fdadapt.html
This adapter is what I've been aiming to construct. I have all the necessary parts, but can't seem find the time to get it done. :(

Re: 2.88 Mb floppy support?

Posted: Fri Jun 24, 2011 2:18 am
by kreutz
Hi Prowler;

Thanks for the links, that information will be really useful as soon as I get my hands on one of those drives.

Best regards,

kreutz

Re: 2.88 Mb floppy support?

Posted: Sun Jul 10, 2011 10:02 pm
by philpem
mr.vince wrote:I am pretty confident that 1.44 drives have a bandpass that will filter out the speedy reversals found on a 2.88MB disk...
Some will. But the main filter is a high-pass: "pass anything of X frequency or faster". After some experiments writing white noise and various bit patterns, I figured that most of my 3.5in drives had a corner frequency of about 2*Fdata (ie. longest possible MFM sequence, "0001"). Anything slower didn't get through the filter.

There's a really good Motorola application note which covers this. It dates back to the days of 5.25in drives and the MC3470 head amplifier chip, but the info is still relevant for the higher-bit-rate drives: ftp://ftp.eskimo.com/u/m/mzenier/AN917.pdf

On top of that, the coercivity differences will mess with the read-amp. I'd be surprised if you could get anything resembling sane data out of a 2.88MB disc placed in a 1.44MB drive.