Korgutils floppy coding

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B C Schmerker
Posts: 5
Joined: Wed Aug 14, 2019 9:00 pm

Korgutils floppy coding

Post by B C Schmerker » Tue Aug 20, 2019 7:54 am

I found more information from SourceForge™ concerning an application suite korgutils: The korgutils README states 10 sectors per track on T-series workstations. (Most MS-DOS 3.5" disquettes are written for 9 or 18 sectors per track, based on a 14.31818 MHz base clock as in the IBM 5170 and 85xx/95xx.) What sample-clock range does KryoFlux support? I'd like to capture all flux reversals in the sector headers and footers as well as sector data and CRC areas for the Image file, as, although KORG probably used delay modulation (MFM), I cannot rule out a 1,3-RLL modulation as of August 2019.

ZrX
Posts: 575
Joined: Tue Dec 06, 2011 9:09 pm

Re: Installing KryoFlux in Windows 8 / 10

Post by ZrX » Tue Aug 20, 2019 9:02 am

These should be split into separate thread.

But KF has no trouble sampling these kind of disks. 3.5" HD media is fine, but 3.5" ED media (these were not in very common use) uses such high frequency that it can't be sampled properly anymore.

Since KF samples at the flux level headers, checksums and such don't matter. It's all captured and then handled during postprocessing the data to verify its integrity. But odd systems might still deviate from the used standards enought that the software is unable to verify the format on the fly.

RLL encoding I've never heard of being used on floppies tho.

B C Schmerker wrote:
Tue Aug 20, 2019 7:54 am
I found more information from SourceForge™ concerning an application suite korgutils: The korgutils README states 10 sectors per track on T-series workstations. (Most MS-DOS 3.5" disquettes are written for 9 or 18 sectors per track, based on a 14.31818 MHz base clock as in the IBM 5170 and 85xx/95xx.) What sample-clock range does KryoFlux support? I'd like to capture all flux reversals in the sector headers and footers as well as sector data and CRC areas for the Image file, as, although KORG probably used delay modulation (MFM), I cannot rule out a 1,3-RLL modulation as of August 2019.

B C Schmerker
Posts: 5
Joined: Wed Aug 14, 2019 9:00 pm

Re: Korgutils floppy coding

Post by B C Schmerker » Wed Aug 21, 2019 4:47 pm

Thanks for the confirm. 1,3-RLL requires double the sample rate of delay modulation due to the flux-reversal timing, but no more bandwidth on the disc media than delay modulation, thus its common use on some early Seagate ST2xx/4xx hard discs via Western Digital controllers. I'll have to experiment with double-, triple- and quadruple-density unformatted 3.5" 2S/80T disquettes on the T1 to find the best performance, but the FD-505's 3.5" transport should be able to pass the image to KF fail-free.

B C Schmerker
Posts: 5
Joined: Wed Aug 14, 2019 9:00 pm

Re: Korgutils floppy coding

Post by B C Schmerker » Sat Aug 24, 2019 12:25 pm

Update: After further reading into the KorgUtils documentation, quadruple density is indicated, as the ten sectors per track use 1024 bytes per sector, for 10240 bytes data per track. (MS-DOS high density is 3.5" 80 track, 18 sectors per track, 512 bytes per sector, for 9216 bytes data per track.)

brightcaster
Posts: 219
Joined: Fri Nov 08, 2013 10:48 pm

Re: Korgutils floppy coding

Post by brightcaster » Sat Aug 24, 2019 2:10 pm

There was/is a commercial program running on dos which works with theese floppies. So the data format must be WD1772 compatible and the kryoflux hardware can read anything that was written with that controller...

https://www.giebler.com/#kdm

David

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