A Long Adventure: Repairing Ultra-Rare NTSC Amiga Ultima 6 | Hacker News Reader

A Long Adventure: Repairing Ultra-Rare NTSC Amiga Ultima 6

amigalove.com

97 pointsdoener26 comments

It seems quite unwise of the OP to write-unprotect the diskette and run an "in-place salvage" software on it. With rare, old media like that, the best chance to preserving them is reading the raw magnetic flux data with specialized equipment. Even putting the diskette in a standard floppy drive might be something to avoid, but surely writing to the media is worse.

I was thinking the same... ADF isn't a preservation format. It's a pity the author didn't first try to make exact copies of these rare disks.

I did, using both Marauder II and XCopy. They failed.

Did you manage to get any partial copies? Might be able to repair those directly.

I was able to copy both data disks flawlessly. The Install disk only copied over about half the contents.

"With rare, old media like that, the best chance to preserving them is reading the raw magnetic flux data with specialized equipment"

Kryoflux is great for that. https://www.kryoflux.com/?page=kf_features

Or if you prefer free-as-in-speech kit, there's also Discferret (www.discferret.org) and a ton of other similar community-developed tools :)

(Full disclosure: I'm one of the guys behind Discferret but it hasn't seen much dev work recently due to lack of time on my part)

Seems the correct project URL is : https://discferret.com

That's interesting i was not aware of this project. I'll take a further look asap. Is there some feature/comparison sheet with Kryoflux available ?

Sorry, quite correct. Apparently I can't even remember my own domain name!

It'll do exactly what a Kryoflux can do, including flux-transition-level read and write. (I'm not sure if the Kryoflux can write). The big differences are that it has a complete Shugart drive interface which matches what floppy drive datasheets advise -- so it's fully open-collector, with the right type of gates.

This also makes it very flexible -- it's been used to read ST506 MFM/RLL drives and decode the resulting output. It's been connected to NEC 8-inch drives with non-Shugart interfaces.

Its only major problem was that it was expensive - about $150 per unit. You could probably get that down a lot by using a more appropriate FPGA. If I did it again, I'd probably use a Lattice MachXO and the Yosys/Nextpnr toolkit, and possibly an STM32 microcontroller.

Practically speaking if you didn't need Winchester support, you could probably use the STM32's timer and PWM peripherals with DMA reload, leaving a single-chip solution with a bit of LSTTL for the drive interface.

Thank you for theses details. Kryoflux can write back a read raw stream or some common image formats (IFP, ADF, G64 etc.)

Heads up, store.discferret.com isn't resolving.

The store closed years ago. I was working 7am-6pm for a long while and just didn't have the time to put in.

I still have about a dozen boards and a few components, actually. Look me up on Twitter (@philpem) or Mastodon (m0ofx@mastodon.social) if you're interested in a board, my usual offer is "beer money plus shipping" :)

Oh, wow. This is pretty cool. I've got some fairly oddball 5 1/4" disks from the 1980's that I'd like to try to preserve, and this looks like it would do the job. I'll echo what another comment says-- the store URL isn't resolving. I'd love to purchase one of these units.

I thought about using Kryoflux in the past, but their licensing is a complete non-starter for me. I'm not going to purchase hardware and license software that limit what I am allowed to do with it.

Unfortunately I don't sell the ready-made units any more -- they're just not cost-effective to sell like that at a price the market will bear.

I want to do a redesign with more cost-effective components (an STM32 Nucleo and a shield or Morpho backpack is one idea I'm considering).

I do have some PCBs left over, a bill of materials and can give you some guidance with part substitutions if you want to DIY one. Feel free to drop me a note on Twitter (@philpem), Mastodon (https://mastodon.social/@m0ofx) or email (via www.philpem.me.uk) if you're interested.

So the guy finally found an ultra-rare disk, the disk had errors on it, and he set his recovery program to WRITE OVER THE RARE DISK? That's a huge no-no.

I had a utility called Hacktrick 60Hz that I seem to recall allowed switching between 50Hz and 60Hz? Discussion of it here:

http://eab.abime.net/showthread.php?t=77875 http://eab.abime.net/showthread.php?t=1925

It was on this disk - which brings back memories! Even though I didn't manage any programming it was the Amiga that led me into a career in tech: https://archive.org/details/amigaformat023disks_1991-06

Interesting that trying on an A1200 had no joy. That machine will switch quite happily between PAL and NTSC timing if you press the space bar at the boot menu.

The author does state "I could play the game on my A1000 Phoenix in PAL mode, but I really wanted the NTSC version."

The problem with running it in PAL mode is that it won't run at the correct speed (I assume). Most of the time when a game was converted to run on a PAL system, developers didn't adjust the game to take into consideration the slower framerate (50 Hz for PAL vs. 60 Hz for NTSC). This is very noticeable on action-based games like Sonic the Hedgehog, where if you are used to the NTSC version, playing the PAL version makes it feel like Sonic's feet are glued to the ground (not to mention how off the music sounds!).

Comparison video: https://www.youtube.com/watch?v=nSSYo0npMhA

I wonder what percentage of Amiga games were designed for 60Hz first! My bet is that it was not high...

(This is also probably not the sort of game where it's a big deal.)

According to this comment, it seems it is noticeable, though: "The speedup can be significant. On my stock A1200 Ultima 6 was annoyingly slow in PAL mode but much more playable in NTSC mode."

http://www.lemonamiga.com/forum/viewtopic.php?p=129566&sid=d...

Just curious: In that one screenshot, what is a "logical block" (= 13098476)? I thought blocks on floppies were far fewer than 13million? (It also says the physical block is 880.)

I believe the 13098476 is a hash table entry that maps to an actual location.

Block 880 appears to be the Rootblock. "The Rootblock contains information about disk : its name, its formatting date, etc...It also contains information to access the files / directories / links". Where "information" is a chained hash table.

My guess is that it looked up the actual location for that hash table entry and found the write error there. Or maybe the hash table entry location itself is borked.

Gory details here: https://github.com/lclevy/ADFlib/blob/master/doc/FAQ/adf_inf...

Great! Thank you!

I can understand why a fan of the Ultima series goes to such lengths :)

"That was the first 1-bomb I've dropped on a seller since using Ebay, and I've been using Ebay for a long time."

If the software was described as "working, tested" then the item is "not as described" and is eligible for a full refund under eBay Buyer Protection, seller's desires be damned; they'll actually take the money back from the seller in that case.

I found amusing that he claim to have paid "a small fortune" for the Ultima VI game... which turns out to be less than one hundred dollars?

I also found it weird that he claims the disc is extremely rare, that none can be found and yet wanted a refund due to a bad sector? And left a bomby ebay review? And was in the end easily able to use it? (In fact, when reading it, my first thought was to use the PAL version copy to replaced the damaged files... which he did last instead of first.)

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