
A Long Adventure: Repairing Ultra-Rare NTSC Amiga Ultima 6 - doener
https://amigalove.com/viewtopic.php?f=7&t=1013
======
0815test
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.

~~~
tiben_
"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](https://www.kryoflux.com/?page=kf_features)

~~~
philpem
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)

~~~
tiben_
Seems the correct project URL is :
[https://discferret.com](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 ?

~~~
philpem
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.

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

~~~
philpem
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" :)

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apricot
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.

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growlist
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=77875)
[http://eab.abime.net/showthread.php?t=1925](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](https://archive.org/details/amigaformat023disks_1991-06)

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mnw21cam
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.

~~~
gryson
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](https://www.youtube.com/watch?v=nSSYo0npMhA)

~~~
tom_
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.)

~~~
gryson
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...](http://www.lemonamiga.com/forum/viewtopic.php?p=129566&sid=d44c84ac0d22f7c41f0bd5bc9ce420fc)

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apples_oranges
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.)

~~~
tyingq
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...](https://github.com/lclevy/ADFlib/blob/master/doc/FAQ/adf_info_V0_9.txt)

~~~
apples_oranges
Great! Thank you!

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

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pixelbath
"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.

------
pierrebai
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.)

