Tetra Quest Original releases

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ijor
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Tetra Quest Original releases

Postby ijor » Sun Jan 06, 2019 3:17 am

I'm resuming here my analysis and current knowledge about the original releases of Tetra Quest.

There are two known releases/versions at this time.

One is the Microdeal US release. A sample of the box is here: http://www.atarimania.com/game-atari-st ... 10517.html

The other version is from the Tri-Star Warriors II compilation. This was dumped very recently by Kodak80. See here: http://www.atarimania.com/game-atari-st ... 23780.html

The Microdeal release is very common, but unfortunately it is not fully working. It has a mastering defect and all known copies have the higher tracks (73-79) unformatted. The high score data and graphics are supposed to be located at that area. The game boot and works fine, but it misbehaves at the end when the high score is supposed to shown. This release has no actual copy protection except for a custom track layout and some dependency on disk load timing.

The only dump we have so far of the Warriors II release doesn't seem to work. Initially we thought the disk was damaged or corrupt. But further analysis shows that the disk is definitely not damaged and the data seems to be correct. It doesn't boot because there is a timing issue that I'll elaborate below.

But what resulted very interesting is that this release is fully copy protected. It has a a very special type of weak sector on track 0 that also is causing problems to Pasti emulation. This is in addition and not related to the timing problem that affects the original disk itself on a real Atari. We also found that the Microdeal release has still the same copy protection check on the code. The Microdeal release was slightly altered to ignore the result of the protection check. In other words, the Microdeal release was actually deprotected by the publisher itself. This means that the Warriors II release was based on an earlier master, probably the first original master of this title!

Except for the protection both releases seem to be almost identical. It is possible to copy tracks 73-79 from the Warriors II release to the Microdeal release and this "patch and mix" of two different versions seems to be fully working.

About the timing issue of the Warriors II release: The game code is partially encrypted. It is decrypted after the first stage loader. The decryption key is obtained by measuring the loading time of the first stage. This is identical in both releases. Identical loading, identical decryption routine and identical decryption key. The Microdeal release has the correct load timing and then decrypts correctly. The Warriors II release has a slightly wrong load timing. Then the decription key obtained is wrong and the game crashes.

The difference in the loading time between both releases is produced by a slightly different sector alignment on a couple of tracks. For the technically oriented, the inter sector gap is different. As a consequence of this different alignment those tracks take an extra disk revolution to load. This couple of extra revolutions is what makes the loading time to be correct or wrong.

If I take the Warriors II dump and realign the sectors on those tracks to match the alignment on the Microdeal release, then the decryption is correct and the dump is fixed without changing not even a single bit.

It is not clear why the alignment of those tracks is "wrong". It might be again, a mastering or a duplicating problem. It is possible that this depends on the RPM speed of the drives. A disk recorded at a different RPM speed would move the sectors to a slightly different angular position. And this might be enough to "correct" the timing.

Either way it seems that they "fixed" the alignment on the Microdeal release. But then it is strange they used a known "bad" master at the compilation release that presumably was much later.

Continuing in the next message ...
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Re: Tetra Quest Original releases

Postby ijor » Sun Jan 06, 2019 3:18 am

Regarding the special weak sector on the Warriors II release of Tetra Quest.

The copy protection of this release is based on a very special weak sector located on sector 2 of track 0. Weak bits, or weak sectors are sectors with data that changes randomly every time you read the same physical sector. In this case some of the bytes change on every read, but not randomly. Each time you read the sector, all these bytes will have the same value. But the value will be different each time you read. The pattern is something like this:

Code: Select all

First read, last 256 bytes (or so) of the sector:
 
CB CB CB CB CB CB CB CB  CB CB CB CB CB CB CB CB
CB CB CB CB CB CB CB CB  CB CB CB CB CB CB CB CB
...
Second read, last 256 bytes (or so) of the sector:
 
BC BC BC BC BC BC BC BC  BC BC BC BC BC BC BC BC
BC BC BC BC BC BC BC BC  BC BC BC BC BC BC BC BC
...


This effect is accomplished by having actually weak bits only at the middle of the sector. The first bytes and the last ones are stable. But the FDC PLL will loose sync after the weak bits, so when reading the bytes that follow these weak bits, and even when are they stable at the flux transition level, they will be not so at the byte level. As a consequence of loosing sync, the FDC will align the bits differently each time, and might even read the clock pattern instead of the data bits.

Currently Pasti is not ready to interpret this kind of weak sector correctly. For Pasti, bits are either random or either stable and constant on every read. That's the first time I found a weak sector with these characteristics, not constant but yet not random. But to be honest, I always suspected that a disk with non-random weak bits might appear. This will be fixed in a future release.

Note that both disk issues that affect this release are completely unrelated. One is the load timing that affects the original disk itself and which appears to be a mastering issue (or at least, it seems so). The issue with the special type of weak sectors affects only the Pasti image. They are also located on different tracks, and produce different behavior. The wrong timing produces a crash. The incorrect handling of the weak sector produces a reboot.
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Re: Tetra Quest Original releases

Postby kodak80 » Sun Jan 06, 2019 6:55 am

Nice status update. Great to hear that the timing on the Warriors II version can be fixed. :D
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Re: Tetra Quest Original releases

Postby Mug UK » Sun Jan 06, 2019 10:01 am

When I had this game (as part of the Warriors compilation) it would never make a workind PaSTi image and now I know why :)
My main site: http://www.mug-uk.co.uk - slowly digging up the bits from my past (and re-working a few): Atari ST, Sega 8-bit (game hacks) and NDS (Music ripping guide).

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Re: Tetra Quest Original releases

Postby ijor » Sun Jan 06, 2019 1:05 pm

Mug UK wrote:When I had this game (as part of the Warriors compilation) it would never make a workind PaSTi image and now I know why :)


You also had that rare version ! 8O 8O

I understand you don't have that disk anymore, do you? Do you happen to still have the non working Pasti image? That would be awesome.
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Re: Tetra Quest Original releases

Postby Mug UK » Sun Jan 06, 2019 1:55 pm

ijor wrote:
Mug UK wrote:When I had this game (as part of the Warriors compilation) it would never make a workind PaSTi image and now I know why :)


You also had that rare version ! 8O 8O

I understand you don't have that disk anymore, do you? Do you happen to still have the non working Pasti image? That would be awesome.


You mean these ones from a decade ago? :)

Warriors.zip
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My main site: http://www.mug-uk.co.uk - slowly digging up the bits from my past (and re-working a few): Atari ST, Sega 8-bit (game hacks) and NDS (Music ripping guide).

I develop a free Word (for Windows) add-in that's available for Word 2007 upwards. It's a fix-it toolbox that will allow power Word users to fix document errors. You can find it at: http://www.mikestoolbox.co.uk

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Re: Tetra Quest Original releases

Postby ijor » Sun Jan 06, 2019 2:17 pm

Mug UK wrote:You mean these ones from a decade ago? :) Warriors.zip


Wow. Thanks a lot! Unfortunately it has exactly the same behavior as Kodak80's dump, and as a matter of fact they seem to be identical.

Do you happen to know if his disk is the one you had? That is, aren't both the same copy by any chance? Otherwise it confirms that it is a mastering problem.
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Re: Tetra Quest Original releases

Postby Mug UK » Sun Jan 06, 2019 2:25 pm

ijor wrote:
Mug UK wrote:You mean these ones from a decade ago? :) Warriors.zip


Wow. Thanks a lot! Unfortunately it has exactly the same behavior as Kodak80's dump, and as a matter of fact they seem to be identical.

Do you happen to know if his disk is the one you had? That is, aren't both the same copy by any chance? Otherwise it confirms that it is a mastering problem.


Sorry Ijor, but I wouldn't have a clue. It was probably bought from eBay or via a job lot probably from Attic Bug or somewhere similar. I no longer have the original disks either as I got rid of loads of them years ago.

Sometimes I can't remember what happened yesterday, let alone a decade ago :oops:
My main site: http://www.mug-uk.co.uk - slowly digging up the bits from my past (and re-working a few): Atari ST, Sega 8-bit (game hacks) and NDS (Music ripping guide).

I develop a free Word (for Windows) add-in that's available for Word 2007 upwards. It's a fix-it toolbox that will allow power Word users to fix document errors. You can find it at: http://www.mikestoolbox.co.uk

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Re: Tetra Quest Original releases

Postby ijor » Sun Jan 06, 2019 5:24 pm

I updated the second post on this thread with a description of the weak sector and how it currently affects Pasti.:

viewtopic.php?f=3&t=35057&p=363168#p363168

Mug UK wrote:Sometimes I can't remember what happened yesterday, let alone a decade ago :oops:


That's perfectly normal. Start worrying when you don't remember what happened yesterday but you do remember perfectly what happened years ago. That would mean you are senile :)
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Re: Tetra Quest Original releases

Postby Marcer » Sun Jan 06, 2019 7:59 pm

There is one more release from software direct i dumped recently
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Re: Tetra Quest Original releases

Postby ijor » Sun Jan 06, 2019 8:33 pm

Marcer wrote:There is one more release from software direct i dumped recently


And where is the dump? :)
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Re: Tetra Quest Original releases

Postby ijor » Wed Jan 09, 2019 4:23 pm

Marcer wrote:im not sure if its workin 100% the disk wasnt so nice.. had trouble with kryoflux it..


Bingo (almost)! Thanks a lot Marcer.

This seems to be, originally, a fully working release. It is slightly damaged, but I would be able to recover because the data seems to be the same as the Warriors II release just slightly damaged, but (big but) with the correct timing. Please PM me a link for the RAW kryoflux files. Is it possible?

This is probably the original UK release, just on a budget packaging.
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Re: Tetra Quest Original releases

Postby ijor » Wed Jan 09, 2019 4:24 pm

I moved the off-topic messages to a separate thread: viewtopic.php?f=3&t=35072

Marcer's dump was moved along with the messages. The dump is damaged and I expect a recovered fully working image will be posted soon, here or at Atarimania. You can still find it in the other thread, If you still want that original damaged dump.
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