Two Questions

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thunderbird32
Posts: 2
Joined: Fri Feb 02, 2018 3:45 am

Two Questions

Post by thunderbird32 » Mon Nov 12, 2018 5:12 pm

Hello all,

First question: I have a copy of WordStar 2000 for the AT&T UNIX PC that I'd like to dump for preservation, and I'm unsure of the best way to do it. If I'm not mistaken, the UNIX PC used a non-standard disk format, and I was wondering what the best way to dump the disk is. Can I just dump them like any other (PC) floppy disk, or am I going to need special settings.

Second question: Does the KryoFlux support 2.88MB floppy disks? Contrary to what I had always believed apparently there was at least one commercial piece of software released on ED disks. Appsoft Image for NeXTSTEP. There's a seller on eBay currently selling a copy, and I'd love to get it archived, but I'm not sure if the KryoFlux can handle it. I DO have a 2.88MB drive in my RS/6000, so I suppose I could just DD it, but it would be nice to have stream files as well.

SomeGuy
Posts: 178
Joined: Wed Feb 18, 2015 8:18 pm

Re: Two Questions

Post by SomeGuy » Mon Nov 12, 2018 7:14 pm

From what I have seen, the AT&T Unix PC uses standard 48TPI 5.25" double sided double density media and drives. They use MFM encoding with 512 byte sectors. There are at least two formats, one that uses 8 sectors per track and one that uses 10 interleaved sectors per track. Obviously these are not DOS formats, and like many Unix systems I believe much of the software was just filesystem-less "tar" files dumped on to the raw disk device.

The good news it is easy enough to save a flux preservation stream, either using a standard 360k drive or a 1.2mb drive using double stepped track spacing to skip odd track numbers.

From there you can use the kryoflux software to decode the preservation stream files in to an IMG file. In some cases you may be able to concatenate multiple IMG files in to "tar" files. However since IMG loses all sector geometry information it is not an ideal disk storage format.

To preserve the sector layout you probably want to save to the ImageDisk format. I see that Bitsavers stores their AT&T Unix PCs in ImageDisk format. The kryoflux software does not natively support ImageDisk however there are several third party tools that can convert a Kryoflux preservation stream files to ImageDisk.

To the best of my knowledge the Kryoflux does not support 2.88mb disks. Obviously reading such a disk would require a genuine 2.88mb floppy drive in the first place. They use a higher bitrate than 1.44mb disks. There seems to be some question if the Kryoflux can even make flux images from such a drive but the decoding commands do not appear to support that.

brightcaster
Posts: 145
Joined: Fri Nov 08, 2013 10:48 pm

Re: Two Questions

Post by brightcaster » Mon Nov 12, 2018 7:22 pm

@ thunderbird32: You may use the search function this forum offers to get quick results and you don't have to wait for somebody to respond... ;-)

viewtopic.php?t=1186

viewtopic.php?t=1015

viewtopic.php?t=198

David

thunderbird32
Posts: 2
Joined: Fri Feb 02, 2018 3:45 am

Re: Two Questions

Post by thunderbird32 » Mon Nov 12, 2018 8:04 pm

@SomeGuy
Thanks for the info! I'll just dump them as stream files then, I suppose. IIRC, the big disadvantage of just doing a stream dump is that it doesn't show you if you have bad sectors, correct? It's been a while since I tried though, and I may be miss-remembering.

brightcaster wrote:
Mon Nov 12, 2018 7:22 pm
@ thunderbird32: You may use the search function this forum offers to get quick results and you don't have to wait for somebody to respond... ;-)

viewtopic.php?t=1186

viewtopic.php?t=1015

viewtopic.php?t=198

David
I didn't see the first one when I searched. Thanks for the heads up. As for the other two threads, I did see them, but both are rather old threads, and quite a lot can change. I wasn't sure if the KryoFlux hardware had been updated in the intervening years.

SomeGuy
Posts: 178
Joined: Wed Feb 18, 2015 8:18 pm

Re: Two Questions

Post by SomeGuy » Mon Nov 12, 2018 9:42 pm

Correct, there is no real error checking with a flux preservation stream dump. But the upshot is you don't have to re-read the disk again and again if you don't know the correct sector decoding parameters (some formats are much more complex). That does mean you may have to re-dump the disk if you find bad sectors later, but the Kryoflux lets you re-dump just selected tracks. The flux histogram displayed in the GUI, once you become familiar with them, can also give you some idea of the read quality.

It is also useful when you need to send the image to third party tools - in this case you would need to use one if you wanted to export to ImageDisk format. (Both the HxC software tool and the PCE emulator flux tools will do that)

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