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Author Topic: Seeking Information on Twiggy Archiving  (Read 16334 times)

anotherLISAguy

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Seeking Information on Twiggy Archiving
« on: January 28, 2025, 12:07:22 pm »

I'm looking for information on the status of any twiggy archive for Apple Lisa 1 Basic Plus v1.0. I know that Sigma7 did a number of backups in 2012, but I didn't see Basic Plus listed.

I have a full set of V1 disks, and it's been suggested that I back them up for posterity before selling. While I agree, I'm apprehensive due to the age of the media. The disks are pristine and don't appear stuck, but I'm concerned about potential damage from spinning them up and reading.

My Lisa machine needs to be dusted off, and spot-checked as it has been just about 20 years since I last had it running. I have reservations about potential head damage, media damage, and other age-related issues. The system was fully functional when it was stored in the 80s for future projects—40 years later, this seems to be that project.

So the question is what am I looking at here?
  • Was a guide ever created for this process?
  • Are there any potential snafus that can happen in this process?
  • What are the concerns 15 years later?

Considering what's involved, I think a video/images documenting the process would be prudent.
Any input would be appreciated.

Reference:
LisaList message: https://lisalist2.com/lisalist1/2102.html
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sigma7

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Re: Seeking Information on Twiggy Archiving
« Reply #1 on: January 28, 2025, 02:33:08 pm »

... I didn't see Basic Plus listed.

I have some kind of Basic on two Twiggies, but one of the disks has a couple of bad sectors in the disk directory. I enlisted the help of Claunia, the Aaru (formerly DiskImageChef) developer to fix those, but I haven't yet tried to install it to check that it was 100% successful.

How many Twiggies is your variety of Basic?

Quote
So the question is what am I looking at here?
  • Was a guide ever created for this process?
  • Are there any potential snafus that can happen in this process?
  • What are the concerns 15 years later?

There is no guide at this time -- please feel free to ask all the questions.

There are very few people that have done this (or few have reported doing so), and so there is not much to compile from; I'd say all the details haven't really been worked out. Since you're just starting the adventure, making some notes/taking pictures of anything non-obvious along the way might help someone else.

My personal experience is that the pre-BLU reports of old Twiggy media easily shedding into oblivion isn't common. Oxide does come off and contaminate the heads so they stop working until cleaned, but I found the media has remained somewhat readable.

Some old media has high friction jackets that keep the disk from turning at the desired speed (which is solved by putting the donut in a more modern jacket).

I recently received a batch of Twiggies to archive, and found two things made a big difference for few disks/tracks for this batch; the upper jacket pad and spoofing the track 0 position sensor. I'll post about those separately.

However, my experience is not necessarily indicative for a general case; Different storage conditions affect the media, and I quite probably naturally avoid working with disks that clog the heads -- my Twiggy usage is different from most.

General advice that I can think of at the moment....

Make sure your archiving setup is working well before trying any rare or valuable Twiggies. That includes:
  • serial interface and xmodem transfers are working: There are reports of transfers failing at the last block (on some varieties of Unix using some USB-Serial adapters), so make sure transfers run to completion.
  • Your twiggy drives can format, read, and write successfully. Although you only "need" one drive, it seems they are all a little different and so more working drives makes it possible to archive more sectors of a difficult to read disk.
  • You have a good way to clean the heads, ideally with a way to verify they are clean or need cleaning.

I do not have a good way to check the rear/upper head short of disassembling the drive. I'm working on a fixture to position a low cost USB endoscope camera for this purpose, but it looks like I won't have a good solution for a while.

I am slowly working on a revision to BLU that I hope will help archive difficult to read Twiggy disks... anyone interested in alpha testing please DM.
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stepleton

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Re: Seeking Information on Twiggy Archiving
« Reply #2 on: January 28, 2025, 02:41:03 pm »

Thanks for backing up these images and for being so thoughtful about preparing to do it carefully. I'm not aware of any copy of Basic Plus 1.0 either, so some good images of that would be very valuable.

I've backed up some Twiggy media before on my own Lisa 1, and I've also been doing some flux imaging of software on more traditional floppy media. The fact that your media do not appear degraded is a good start, if a bit surprising: Twiggy disks (especially from Apple) have shown a tendency to oxidise or otherwise degrade, particularly around the head access slots and the hub (i.e. where the disk media is exposed to the outside environment). It would be very unlikely for your disks to come to any harm if you rotated them by the hub, so you might want to consider doing this and getting a good look at the entire disk surface. Just don't touch the media itself, of course.

What I would do next is evaluate the condition of your Twiggy drives now and try to use them with media you don't care about. It is possible to make "new" twiggies out of HD 5.25" diskettes by carefully removing the "cookie" from the disk jacket and then cutting more holes into the jacket in the appropriate places. If you have a Lisa 1 with two Twiggy drives, and if you can read a disk written in one drive in the other drive (try it both ways), then it is a good sign I think that your disk drives are in a good condition and stand a good chance of being in good alignment. (It would be strange for them to go out of alignment in exactly the same way.)

Naturally it is useful to clean the heads of your floppy drives with isopropyl alcohol or similar before and between read attempts. A swab on a long stick can help you reach deep into the drive to clean the rear head; the forward head is easily reached.

The tool of choice for working with (and backing up) Twiggies is BLU. You will need to connect to your Lisa's serial port with a serial cable to a modern computer in order to get the data you recovered from the disk into the world of 2025.

I am not sure I'll have a chance to document the process carefully, but if you wish we could talk over a video chat and I could show you what I would do on my machine. This is probably an easier way for me to show BLU at work. I am on UK time, however, so scheduling could be tough.

There are other people on LisaList who do Twiggy data recovery --- more recently than I have --- and it couldn't hurt one bit to have instructions and information from them if they have a chance!
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stepleton

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Re: Seeking Information on Twiggy Archiving
« Reply #3 on: January 29, 2025, 08:11:08 pm »

PS: I'm curious to learn more about your modifications to the front head felt pad, as the front head in my #2 Twiggy isn't dependable (you can see old posts about it from years ago; it works if you gently apply pressure to the top of the disk jacket adjacent to the head), and I wonder if a new felt pad might remedy the problem.
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sigma7

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Re: Seeking Information on Twiggy Archiving
« Reply #4 on: January 29, 2025, 10:11:34 pm »

PS: I'm curious to learn more about your modifications to the front head felt pad, as the front head in my #2 Twiggy isn't dependable (you can see old posts about it from years ago; it works if you gently apply pressure to the top of the disk jacket adjacent to the head), and I wonder if a new felt pad might remedy the problem.

The pad I referred to recently is not the felt circle opposite the head, it is the long rectangular foam one that presses on the jacket to the right of the front head opening.

In summary:

I had "disabled" that foam pad a long time ago when I first started working on BLU as it was exacerbating the high friction jacket = too slow spin problem. (I wrapped paper around and taped it so the foam didn't press on the jacket.)

The batch of Twiggies Justin sent last year for archiving presented reading difficulties that I didn't have before. One of the problems was that the bottom side of one of the sets wouldn't read, but the other sets were fine.

I thought that maybe the head pad pressure was off from having tweaked the spring, so set about measuring it, and when looking up the spec, saw in the Twiggy manufacturing instructions that they specified the upper pad arm and carriage were to be considered a matched set.

I wondered if I somehow had swapped the arm between my two drives, although I think it unlikely. As a result I was pushing the arm side to side to see if the placement of the pressure pad had an effect.

More or less by accident I discovered that slightly altering the angle the media travelled over the head fixed the readability. I found some very soft foam to make a new rectangle from and having installed that, the lower side of those disks became readable.

I didn't see any obvious warp in the jackets of the problem disks, so perhaps there was something inside that affected the travel over the head.

I'm hoping to measure the force of the new pad in some way to provide a better description than "very soft".

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anotherLISAguy

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Re: Seeking Information on Twiggy Archiving
« Reply #5 on: January 30, 2025, 11:56:28 am »

****POST MOVED TO ITS OWN TOPIC****
« Last Edit: January 30, 2025, 04:58:28 pm by anotherLISAguy »
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sigma7

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Re: Seeking Information on Twiggy Archiving
« Reply #6 on: January 30, 2025, 02:22:24 pm »

Thanks for preparing the outline!

I see items where you'll find there is a clear difference of opinion and experience among us, so if the format is set up to allow multiple points of view or approach, that may encourage participation.

I suggest moving this section to a separate topic if you'd like to suggest a new title, and perhaps into a sub-board for Lisa repair rather than the all-encompassing general category. In that way we could make separate topics for different subassemblies easier to find.

Ideas/suggestions/requests?
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anotherLISAguy

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Re: Seeking Information on Twiggy Archiving
« Reply #7 on: January 31, 2025, 01:19:04 pm »

Agree and done! :)
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