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STAC images

STAC tape

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#1 ijor OFFLINE  

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Posted Tue Jul 4, 2017 9:36 PM

A small collection of some CAS images in the STAC system (see http://atariage.com/...covery-sources/for a description of the system)

 

I'm not familiar how exactly Altirra, and the CAS format can handle custom tape formats. But I recorded these CAS images in Altirra. Loaded them with Altirra and they seem to work fine. You can even test the error recovery if you want.

 

A handful of "big" titles are included, most of them never published on tape. They were all adapted for a single stage load:

 

M.U.L.E

Kennedy Approach

Lode Runner Championship

Strip Poker

Zorro

 

MULE is, of course, a special case. The gorgeous loading screen was completely omitted. The goal was to produce a "file" that would load with a single stage on a 48K machine, at (almost) all cost. The whole initial selection screen was replaced with a very simple text based selection with just a couple of options. Yeah, almost a crime, I know. But if you didn't have a disk drive at the time, you would die for playing MULE even with those limitations.

 

Lode Runner Championship was based on the only version I had access then. IIRC it has one or two screen that I think they were corrupt.

Attached Files


Edited by ijor, Tue Jul 4, 2017 9:52 PM.


#2 ijor OFFLINE  

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Posted Tue Jul 4, 2017 9:48 PM

Note. You need to disable, at least, C: acceleration on Altirra. If still doesn't work try to disable all acceleration altogether. Try to configure Altirra for maximum compatibility. The loader requires an XL/XE system (64k).


Edited by ijor, Tue Jul 4, 2017 9:48 PM.


#3 Madi OFFLINE  

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Posted Tue Jul 4, 2017 11:33 PM

Note. You need to disable, at least, C: acceleration on Altirra. If still doesn't work try to disable all acceleration altogether. Try to configure Altirra for maximum compatibility. The loader requires an XL/XE system (64k).

And to remind inpatient persons like me to press F1 while loading the games via Altirra to reduce loading time.

 

madi



#4 Mclaneinc OFFLINE  

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Posted Wed Jul 5, 2017 3:34 AM

Very nice Iljor, the difference is great.....

 

Works great on Altirra with the C: acceleration turned off....



#5 ijor OFFLINE  

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Posted Thu Jul 6, 2017 12:21 PM

Very nice Iljor, the difference is great.....

 

Unfortunately there are no CAS images of the original tape versions of Kennedy Approach and Zorro at Atarimania. They were literally a torture. Not only because they didn't have, of course, turbo or error recovery. But they loaded in multiple stages and multiple times. IIRC Zorro loaded from tape each time you passed to a new level, and this of course means you had to rewind to restart the game. For this purpose it was recorded on two sides (or two tapes? don't remember). I believe Kennedy Approach had a similar method.



#6 ijor OFFLINE  

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Posted Thu Jul 6, 2017 12:42 PM

A few so called STAC master disks, without disk copy protection. Each disk has the recording system and a handful of games to record. Each disk must be booted separately. Works fine and you can record your own CAS images under Altirra. Again, disable, at the very least, C: acceleration. Remember you have to use the Tape Control dialog on Altirra to press the virtual record button.

Attached Files



#7 tschak909 OFFLINE  

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Posted Thu Jul 6, 2017 2:46 PM

So, interesting, based on the audio data i see here, roughly 991 bits per second transfer rate, using the same mark/space tones?

 

-Thom



#8 ijor OFFLINE  

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Posted Thu Jul 6, 2017 8:39 PM

So, interesting, based on the audio data i see here, roughly 991 bits per second transfer rate, using the same mark/space tones?

 

Yeah, those images were recorded at that bit rate. And if you check the sources on the other thread you would see that's the default Pokey divisor ($380). You could perfectly well use higher rates. The loader doesn't even have to be modified. But reliability starts suffering pretty fast. It depends a lot on several factors. I don't remember all the statistics, but this rate was selected because it was a reasonable compromise under the normal, non ideal conditions that most users had.

 

Besides the higher bitrate there is also a smaller overhead. I am too lazy to do the math right now. But bigger blocks plus much shorter IRG shields a higher "effective" bit rate than standard even if you would use the same Pokey divisor.

 

On many of the larger titles, the saving because of the compression was even more significant than anything else.

 

And yes, the frequency of the tones, if that what was you were asking, had to be the standard ones because that's the frequencies that the filters at the tape player were supposed to decode when reading.



#9 tschak909 OFFLINE  

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Posted Thu Jul 6, 2017 8:41 PM

of course, you'd have to alter the tape drive comparators to do any other mark/space tones. 

 

very cool indeed. I had a massive deep dive into the whole cassette system when decoding the Atari Educational System master cart and its tapes (which are very much like classical modem transmission, the data is simply just streamed out.) :)

 

-Thom



#10 Rybags OFFLINE  

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Posted Thu Jul 6, 2017 9:40 PM

Nice.  I'm not sure what the predominant cracked MULE format was but the one I have from memory is a binary file that's disk bound.

It takes over the load process after about 1 sector and retains the full title sequence once loaded.

The way it is, it's bound to the Dos 2.x filesystem and disk unit 1 but could probably be adapted fairly easily to be device independant.

I don't seem to have it imported, only got it on floppy ATM.

 

ed - I also had a play with the error/retry stuff.  To do that, just move the tape pointer around while it's loading in Altirra.


Edited by Rybags, Thu Jul 6, 2017 9:42 PM.


#11 ijor OFFLINE  

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Posted Thu Jul 6, 2017 9:57 PM

Nice.  I'm not sure what the predominant cracked MULE format was but the one I have from memory is a binary file that's disk bound.

It takes over the load process after about 1 sector and retains the full title sequence once loaded.

The way it is, it's bound to the Dos 2.x filesystem and disk unit 1 but could probably be adapted fairly easily to be device independant.

 

I don't remember MULE as a binary file, the cracks I knew were boot disks.

 

The problem with MULE is that it doesn't fit in RAM, not on a 48K machine. So the initial stage that includes the title sequence and the players selection uses (partially) the same memory as the main program. That's why the original loads in two stages. You can make a file if you insist, but not a single stage load. The file would need to continue loading somehow before starting the game.



#12 Rybags OFFLINE  

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Posted Thu Jul 6, 2017 10:14 PM

I'll have to check mine out and compare to what's out there.

 

Actually, I'm fairly sure now that it loaded to the character select/title sequence then once you finished that it loaded the remainder of the game.   Once you'd finished a game it went to the minimal menu.



#13 ijor OFFLINE  

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Posted Fri Jul 7, 2017 6:58 AM

Actually, I'm fairly sure now that it loaded to the character select/title sequence then once you finished that it loaded the remainder of the game.   Once you'd finished a game it went to the minimal menu.

 

That's how the original works. This is why I'm saying you can't make it "single stage". It would have been possible to make a multi stage tape version, but that was against my goal. For starters, it is rather frustrating to start the game, then have to wait once again for additional loading.

 



#14 baktra OFFLINE  

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Posted Fri Jul 7, 2017 7:23 AM

So I take it that conversion of games like Ridiculous Reality (shipped as binary load file with dozens of segments) to STAC is out of question. Right?


Edited by baktra, Fri Jul 7, 2017 7:24 AM.


#15 Rybags OFFLINE  

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Posted Fri Jul 7, 2017 7:50 AM

It should be able to work.  In it's case it comes down to not overwriting the loader or it's work area.  I created an ATR with games loader for emulation use so I could do savestates and it worked OK.  Given the source of STAC is available it could be assembled to work with many games.   Probably even possible to do one that copied the OS to Ram and ran from the $CC00 area, that would allow full use of the normal 48K area.



#16 ijor OFFLINE  

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Posted Fri Jul 7, 2017 8:19 AM

So I take it that conversion of games like Ridiculous Reality (shipped as binary load file with dozens of segments) to STAC is out of question. Right?

 

Multiple segments and multiple stages are two different things. Multiple segments, as long as they load all at once, is not a problem at all.

 

But even multiple stages are, at least in theory, possible. Only that I didn't like the concept for tapes, so I never shipped any title that worked that way.



#17 vitoco OFFLINE  

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Posted Fri Jul 7, 2017 9:10 PM

A few so called STAC master disks, without disk copy protection. Each disk has the recording system and a handful of games to record. Each disk must be booted separately. Works fine and you can record your own CAS images under Altirra. Again, disable, at the very least, C: acceleration. Remember you have to use the Tape Control dialog on Altirra to press the virtual record button.

 

STAC master disks? So the entire process to write a game into a tape required to save it first in a disk using a propietary format? I haven't analyzed the soure code yet, but I guess that each game in the master disk already has all the blocks preformated, including RLE... Am I right?



#18 ijor OFFLINE  

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Posted Fri Jul 7, 2017 10:43 PM

 

STAC master disks? So the entire process to write a game into a tape required to save it first in a disk using a propietary format? I haven't analyzed the soure code yet, but I guess that each game in the master disk already has all the blocks preformated, including RLE... Am I right?

 

Hi vitoco,

 

It isn't a strict requirement of the STAC system, but yes, that's more or less how I used to ship. The blocks weren't preformatted (it wouldn't provide a significant gain), but the files were already compressed. It is perfectly possible to implement a program that would write STAC tapes from a plain binary file, but I never provided something like that. This was for a couple of reasons. The main reason was that I considered the quality of the program to be recorded as the most important factor. A good recording system is worthless if the actual game doesn't work well. I personally adapted, converted and verified each one of the titles on the master disks. In many cases, such as most of the games I posted in the first post of this thread, the adaptation is probably more important and more valuable than anything else.



#19 devwebcl OFFLINE  

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Posted Sun Jul 9, 2017 2:46 PM

Very nice Iljor, the difference is great.....

 

Works great on Altirra with the C: acceleration turned off....

 

Are you using any other special configuration ?

I can't get it to work...



#20 Mclaneinc OFFLINE  

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Posted Mon Jul 10, 2017 4:26 AM

Are you using the Altirra built in OS by any chance?

 

Just needs XL OS, I use version 2 and the C: acceleration off...By default Altirra auto selects firmware depending on its availability, I make it use version 2 as it seems the best choice for XL mode.

 

EDIT:

 

Just tried the various OS's in XL mode and 1, 2 and 3 all happily load the STAC images, Altirra built in isn't so happy and crashes..Again, loading with the C: unticked in Acceleration does work.

 

Can't think of anything other than memory being 64K (tested at 64K and fine) or above, I did not try it with and extra devices like U1MB etc, just as a plain XL.

 

Paul


Edited by Mclaneinc, Mon Jul 10, 2017 4:43 AM.


#21 Wilheim OFFLINE  

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Posted Mon Jul 10, 2017 7:16 PM

Thanks Iljor, for sharing this treasure! I really loved the STAC tape loading system, specially the turbo and error recovery system.

 

I remember also that you launched an special version of International Karate, that featured 4 scenarios, that is a much improved version than the original tape version, which included only 1 scenario. Do you you still have it to share?

 

Thanks!



#22 ijor OFFLINE  

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Posted Tue Jul 11, 2017 3:45 PM

I remember also that you launched an special version of International Karate, that featured 4 scenarios, that is a much improved version than the original tape version, which included only 1 scenario. Do you you still have it to share?

 

Here you go ...

 

Attached File  InternationalKarate-Stac.zip   33.38KB   17 downloads

 

I forgot all the versions that I adapted. I am getting old. :)



#23 ijor OFFLINE  

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Posted Tue Jul 11, 2017 3:46 PM

 

Are you using any other special configuration ?

I can't get it to work...

 

Could you make it work?



#24 devwebcl OFFLINE  

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Posted Tue Jul 11, 2017 6:48 PM

Are you using the Altirra built in OS by any chance?

 

Just needs XL OS, I use version 2 and the C: acceleration off...By default Altirra auto selects firmware depending on its availability, I make it use version 2 as it seems the best choice for XL mode.

 

EDIT:

 

Just tried the various OS's in XL mode and 1, 2 and 3 all happily load the STAC images, Altirra built in isn't so happy and crashes..Again, loading with the C: unticked in Acceleration does work.

 

Can't think of anything other than memory being 64K (tested at 64K and fine) or above, I did not try it with and extra devices like U1MB etc, just as a plain XL.

 

Paul

 

Yes, it was the firmware, thanks a lot !



#25 devwebcl OFFLINE  

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Posted Tue Jul 11, 2017 6:48 PM

 

Could you make it work?

 

Yes, it is working now, thanks !







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