Support in Steem - teaser

[Steven Seagal]

Soon the "Coming Soon" thread of Steem will be updated with some details, but it takes time and you know me, can't wait to brag, a sad case really, but another fine day for Atari ST emulation!

[JimDrew]

Finally! Nice!

Let me know if you need any help with testing, images, etc.

[Stefan jL]

Great Will you release an beta with SCP support before the full release?

[Maartau]

Steven's another mission .

[AtariZoll]

That screenshot with : ... A: ... If it is a hard disk ....
That seems not wise - A can not be hard disk. Unless it is SD card in some HxC or other floppy emulator. But that's not case in Steem .
Usual message by non-accessible hard disk is: Data on the disk in drive C: may be damaged.
So, what's the point with that message ?

[kodak80]

Cool. Good work. I look forward to seeing SCP finally supported in Steem.

[JimDrew]

That screenshot with : ... A: ... If it is a hard disk ....
That seems not wise - A can not be hard disk. Unless it is SD card in some HxC or other floppy emulator. But that's not case in Steem .
Usual message by non-accessible hard disk is: Data on the disk in drive C: may be damaged.
So, what's the point with that message ?

Looks like progression to me. Non-working, decoding a sync from flux to MFM, decoding flux to MFM and also to FDC decoded data, and finally booting a disk.

[AtariZoll]

I'm talking about message text - why mentioning hard disk in case of drive A ?
Surely there is progress in supported image formats. Just a note to people not familiar with Atari: during boot process can not appear such windowed message

[Steven Seagal]

That message box only illustrates that this didn't work at all. You got it by clicking 'Show info'. Now it's better.
It's a proof of concept, my flux to MFM decoder is lame. I believe Chessmaster 2000 isn't protected.

[JimDrew]

Chessmaster is very protected for the Amiga, C64, and IBM PC. I can not imagine that they released it unprotected for the Atari ST.

[AtariZoll]

Chessmaster is very protected for the Amiga, C64, and IBM PC. I can not imagine that they released it unprotected for the Atari ST.

Now it's my turn to put screenshot :

Chessmaster2KfromSTimg.png

You will see above if running from ST image - simple copy of original. Protection is primitive: 10 sectors/track on tr. 79, others are with 9 sec/tr - but it was year 1987 .

[Steven Seagal]

Funny.
I picked Chessmaster 2000 because Aufit reported no protection, better start with an easy case. OK, a track with 10 sectors is relatively easy, we work on a track basis anyway.
Normally a beta will be uploaded Sunday for the privileged. Who knows maybe some classics will run already.
Still, the current decoder isn't great, if there are tricks with $C2 address mark ($5224) I'm afraid it will fail, for example.

[JimDrew]

Let me know if you need help on flux<>MFM decoding. I code only in assembly (all CPUs including 68K), so I could lend a hand.

DrCoolZic has detailed info on the WD1772 and some of the state machine functionality. This is something that I am working as well for another project (1581 disk drive emulator).

[Steven Seagal]

Let me know if you need help on flux<>MFM decoding. I code only in assembly (all CPUs including 68K), so I could lend a hand.

DrCoolZic has detailed info on the WD1772 and some of the state machine functionality. This is something that I am working as well for another project (1581 disk drive emulator).

Your help is welcome (see my PM).
Normally DrCoolZic will release the source code of Aufit one day, I guess everything we need to know is in there.
Meanwhile I'll check some cases to progress, counting on beta testers to signal bugs.

[JimDrew]

Once you get the WD1772 emulation worked out, we will be able to use .scp images to load 100% of everything ever made, in its original copy protected format. This it the case right now for the Amiga emulations using .scp images, and it really adds to the emulation experience.

[JimDrew]

You guys are going to be in for a treat!! I just tested the beta Steem and it works amazingly well with .scp images. Don't let Steven fool you, it's working very well for a 1st attempt! I am able to load everything from Psygnosis except Obitus. Dungeon Master (single revolution with "fuzzy bits") works perfectly! Ghostbusters II (NFA), Wizball (Copylock), Fire and Forget, and countless others work just fine.

Nice job!

[kodak80]

Where do I sign up for beta testing? I would love to use my SCP images without having to convert them.

[JimDrew]

Yeah, and I am testing primarily single revolution images, which is all that is necessary (just like a real floppy). I am going to make an option to strip additional revolutions in image files so that the size of the files can be reduced dramatically. If I can get Steven to support compressed files, we can get the file size down under 2MB.

PM Steven about beta testing.

[Stefan jL]

You guys are going to be in for a treat!! I just tested the beta Steem and it works amazingly well with .scp images. Don't let Steven fool you, it's working very well for a 1st attempt! I am able to load everything from Psygnosis except Obitus. Dungeon Master (single revolution with "fuzzy bits") works perfectly! Ghostbusters II (NFA), Wizball (Copylock), Fire and Forget, and countless others work just fine.

Nice job!

Yes it worked very well, it loads most games
Steven do you want a list of games in SCP format that don't work correctly in the beta?

[Steven Seagal]

I'm afraid you're a bit (got that one? ) enthusiastic.
It's not that good. It misses a proper "inspection window" emulation, the current system is too primitive.
Granted it is fortunate that many games already run as it is.
Dungeon Master (single revolution with "fuzzy bits") works thanks to a hack, my goal is to have it working with a proper "inspection window".
I noticed that the current beta can't even load Chessmaster 2000. It's fixed already, but funny that it had to be the one I showcased, broken in 2 days

[JimDrew]

Sent you a PM with info on weakbit and strongbit implementations. It's a great start for sure!

[Steven Seagal]

Well I have some great news.
Now there's a proper "inspection window" emulation, in fact Steem uses the correct "DPLL" algorithm for WD1772, as directly (it's C++) ripped off from the great MAME project. Didn't know they were more advanced than us in drive emulation.
Instead of changing delays into 001 01 etc. sequences, delays are sent to that new routine, that does phase and frequency correction by itself, and without us needing to understand how it works, it just does its thing.

Please endure some more "progress" screens, five in this post...











EDIT: add "DPLL"

[Steven Seagal]

Even after the licence box it would fail. Simple programming error that made all bit timings off.
And finally:





Starglider didn't work with the primitive system because it just couldn't handle phase error.
It's not the protection, just "dirty" data, a fine case then.


Yes we turrican!
The difficulty here is data written over index pulse.
I see no other way than making sure that we start on rev1 and end on rev2, but we need to analyse commands and it's quite a hack.


For Dungeon Master, one rev, we also need to introduce randomness when delay is +- 5 microseconds, else it will read exactly the same way each time, after all the copy is perfect and the controller is synced on data! That's a hack too then.

But previously the whole flux to MFM decoder was a hack!

There are other cases not working I still must check, like Jupiter's Masterdrive, Albedo, Leavin' Terramis, probably a lot more.

EDIT: it's the 4rev version of DM working, but even if we always use rev 1 it's OK.
Not sure it's a hack after all, if we emulate jitter.
Albedo: it was a $C2 sync mark issue, flux decode to "5224" but then to "4489":

Code: Select all

    5224 0101001000100100    5224
         01000100100 01001  followed by 4, 6 
    4489 0100010010001001    -> 4489, we will sync on this

[JimDrew]

As I said in my PM, you don't need to delay anything to duplicate weakbits with a single rev. During the decoding of the track, you will know if the last MFM bits are an even MFM byte. If not, then by wrapping back around to the start of the track data will automatically introduce a different result every virtual revolution. If the track data does decode to an even MFM byte, you can repeat the first bitcell for either even or odd virtual revolutions. Of course, any bitcell time that is outside of the normal clocking window (<3.5us or >8.5us) is a weakbit and you can take the next bitcell value (if also invalid), add them together, and then divide by a random divider and use both of those values for decoding. This is exactly how a real data separator behaves when an invalid bitcell time is encountered.

NFA over index is easy with .scp images. You will see a NFA at the start of the track and at the end of the track. So, when a NFA is encountered at the end of the track, the start has to be checked to see if the NFA continues. You only need a single revolution here too.

These methods are used with the Amiga emulators, and because of this 100% of every type of copy protection can be loaded without any "hacks" required.

Nice job. Can't wait to do more testing!

[Maartau]

Great job [smilie=greencolorz4_pdt_01.gif] (As always )