ITT 2020 5.25" Disks

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davidlandy
Posts: 5
Joined: Mon Sep 26, 2016 8:32 am

ITT 2020 5.25" Disks

Post by davidlandy »

I have some 5.25" floppies which were written on an ITT 2020 (an Apple II clone) around 1980. They contain copies of the first programmes I ever wrote, so are of some sentimental value. The disks themselves look in good shape and they have been stored in a protective hard-plastic case.

So far, I've managed to get the KryoFlux installed and working, and have retrieved the contents of all six disks to stream.

They appear to be DOS 3.2 images which would align with the documentation I can find on the web for the ITT 2020 (they never released DOS 3.3 so they should be in the 13 sector format).

The trouble is, there are bad sectors on all of the disks :(

And, I can't figure out what to do with the img files created.

The 5.25" floppy drive is a YE DATA YD-380B (1.2mb).

My questions are:

1. Is there a software tweak I can apply to improve results when reading the disks? The KryoFlux manual suggests some command-line options for reading DOS 3.3 disks to help with track alignment(?), but these don't work with the DOS 3.2 settings.

2. Should I try to clean the disks? I have seen several suggestions for doing that on this forum.

3. Is there a software emulator for DOS 3.2 - or any other way of retrieving the files from the img?

4. Should I try a different (supported?) floppy drive and see if it helps?

5. Would I get a better result if I sent my disks off to a professional service?

Thanks in advance for any help/advice!

brightcaster
Posts: 237
Joined: Fri Nov 08, 2013 10:48 pm

Re: ITT 2020 5.25" Disks

Post by brightcaster »

For retrieving single files from the disk image ciderpress should do the trick...

http://www.a2ciderpress.com

Regards, David

SomeGuy
Posts: 249
Joined: Wed Feb 18, 2015 8:18 pm

Re: ITT 2020 5.25" Disks

Post by SomeGuy »

Were just some of the sectors bad? Or was it showing everything as unreadable?

You might try a 360k drive instead of a 1.2mb drive. Sometimes that can have better results.

There are also lots of Apple II emulators out there, and I would expect at least some of them would support Apple DOS 3.2 sector images.

It is always a good idea to start with a visual inspection of the disk and carefully clean any visible gunk. Sometimes, though, there can be residue and stuff that isn't immediately noticeable. Also, don't forget to clean your drive heads.

spags
Posts: 91
Joined: Sun Sep 09, 2012 5:46 am
Location: Australia

Re: ITT 2020 5.25" Disks

Post by spags »

Don't forget to try the drive density select AGC option (from memory -dd0 or -dd1 from the command line), which might improve your results. This would be as good as it gets in regards to a "software" tweak.

davidlandy
Posts: 5
Joined: Mon Sep 26, 2016 8:32 am

Re: ITT 2020 5.25" Disks

Post by davidlandy »

Thanks to everyone for getting back to me so quickly - apologies for my delayed response.

@brightcaster

Ciderpress - just what I needed! :-)

@SomeGuy

Yes, only some of the sectors were bad, a lot of them were good, sadly one of the bad sectors has hit a file I really wanted to recover, so I'm going to keep trying...

I'll try and source a 360k drive and see if that helps.

There's no visible gunk on the disks but I can see small visible bands - is that bad?

And... How do I clean the drive heads?

@spags

I tried setting "Density Line Low" in the GUI and re-ripping, but got the same result :( (I also added -dd0 to the "other options" just to be on the safe side...)

spags
Posts: 91
Joined: Sun Sep 09, 2012 5:46 am
Location: Australia

Re: ITT 2020 5.25" Disks

Post by spags »

Oh well. If you haven't tried it already, it is worth specifically attempting -dd1 in "other options" as well.

I find that for only 1 or 2 bad sectors in a track, I have a chance of a successful read after many retries. How many retries I attempt depends on the disk condition and my desperation. I set many retries anywhere from 15 to 40, but I will attempt this in multiple "sessions" (say 3-5) - I prefer to give my media a short rest period instead of turning for hundreds of rotations non stop. I also try combinations of reducing/increasing the number of rotations as well and sometimes (by chance?) manage to get an extra sector by setting to a very low number (1,2 or 3).

If there are quite a few bad sectors in a track (say 4 or more), I generally assume it is a lost cause. I'll retry just to see if I can get an improvement by luck, but I don't persist with those ones as I find at best I might get only 1 or 2 extra good reads from any given retry.

There are likely to be multiple online videos or tutorials on cleaning drive heads. Google and watch/read a few different ones so you get a good idea. The general process is to raise the drive head and use an IPA dampened q-tip to very gently wipe away any gunk from the small while square heads (don't scrub and don't forget to do both the top and bottom head). When I am doing such maintenance, I also tend to add a little smear of Vaseline to any of the sliders or worm gears that I can see (where it is obviously in requirement for it). Don't overdo it though as you don't want any to fly off or drip into any floppy disk surface down the road.

I often find visible bands on floppies and have never really wondered about whether that is good or bad. It is definitely bad if you can actually see through the bands (when held up to a light) or close to it, but if your bands seem pretty consistent circular rings around the entire disk then I'd say it is probably "normal". Visible "arcs" are a warning sign that there has been physical damage to the media surface. I seem to recall seeing circular rings (not arcs) on relatively new or rarely used media back in the day as well.

davidlandy
Posts: 5
Joined: Mon Sep 26, 2016 8:32 am

Re: ITT 2020 5.25" Disks

Post by davidlandy »

Thanks spags, I'll give the retries thing a go, I've also discovered from the service manual (online) that my drive is HD only, so no point trying -dd1 or -dd0 it's just going to read HD whatever the settings! Also it's fixed on 360 rpm, if that makes any difference - some posts here lead me to suspect it might.

So... I've just ordered a used 360k drive from ebay and will wait and see if that improves things any before trying anything else.

Re the retries thing, am I right in thinking that there is a risk of damaging the media from excessive retries? I'm thinking hopefully not (if the disk drive is OK) but you never know...

Thanks for the info re the arcs, sounds like the disk is probably OK then as it's not scratched through.

Have to say when I read about q-tips and IPA my first thought was "beer"!!

Maybe I have more in common with Homer Simpson than I thought :)

davidlandy
Posts: 5
Joined: Mon Sep 26, 2016 8:32 am

Re: ITT 2020 5.25" Disks

Post by davidlandy »

PS. I have read on other posts that people don't recommend head-cleaning disks - could anyone explain why is this? I remember using one back in the day with no ill effects... and the tech ref for my disk drive (for example) specifically says to use one for cleaning and not to try and clean it by hand. Bit puzzled... but perhaps things change over this many years?

spags
Posts: 91
Joined: Sun Sep 09, 2012 5:46 am
Location: Australia

Re: ITT 2020 5.25" Disks

Post by spags »

It is still worth a try even though the drive is HD - there may be jumpers or toggle switches in the drive circuitry that affect the drive operation and specifically setting or unsetting the density can make a difference (it might not, but it can).

Frankly, there is a risk from simply placing your floppy into the drive and this was even the case 30 years ago. It only takes a piece of dirt to make its way inside the jacket and then scratch the surface next time the disc is used. You need to excercise common sense here and get a little hands-on. I usually visually inspect the media to check if it looks intact and is free from visible imperfections (such as warped media or mold growth). I will also manually rotate the media in the jacket to see if it turns freely and without any unusual noises. If it passes these common sense tests, then the disk is probably (but not definitely) structurally sound for use. Definitely be ready to eject the floppy from the drive if it sounds unusual on that first try. Personally I have never seen a floppy in such a bad condition that it is physically falling apart (scratches and mold being the worst I have observed), but I seem to recall that falling apart floppies have been reported elsewhere on these forums so it obviously can happen so reducing retries and rotations would definitely be notable in such instances. I think detached hub rings have also been reported here.

I think you have to keep in mind that floppies were designed to be turned inside the media and make contact with the heads with a reasonable amount of usage. I have read that they have a dry lubrucated surface, but that this lubrication can be compromised after many decades. If the media turns freely and without any abrasive noise, then I wouldn't hesitate to give it a few retries but I personally wouldn't leave it spinning in that drive for minutes at a time set on 100 retries as I don't consider that a reasonable amount of usage. Where there is friction, there is also heat and while it isn't going to start a fire I don't feel like it is wise to subject the floppy to this condition for a considerable length of time.

I think that head cleaning disks are considered to be abrasive, but admittedly I use them as a quick and dirty fix sometimes. Remember what they sound like when they are turning in your drive? Definitely not like a normal floppy. I think some drive heads also have a soft pressure pad on them opposite the actual read/write heads and such cleaning disks probably aren't very good for them.

SomeGuy
Posts: 249
Joined: Wed Feb 18, 2015 8:18 pm

Re: ITT 2020 5.25" Disks

Post by SomeGuy »

Cleaning disks are usually fine for a quick clean, and it saves you from having to take everything apart. But I have seen extreme cases where a cleaning disk will not get all the gunk, and going in with a q-tip is the only way. I doubt that is an issue here.

It is always hard to tell if a disk itself is clean until trying. If these were well stored and look good, then they are probably OK. For random 5.25" disks I get from eBeh, I have made a habit of washing them with water first.

Given that this was from an Apple II style system, my suspicion is that the head alignment of the original system may not have been perfect when it wrote that sector. A genuine 360k" drive has a wider head like an Apple II's and can better compensate for that and other issues.

In general, you want to spin the disk as little as possible. I usually recommend dumping to the "preservation" format, and then going back and analyzing/decoding it later. If it is just one track, you can select that track in the Kryoflux GUI (or specify the track on the command line) and use interactive decoding to retry just that track. Keep a close eye on the disk to make sure it isn't getting worse as you use it. If it is, stop and wash the disk out. If there are a number of disks that were stored together, it is usually best to experiment with an "unimportant" one first.

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