Steven Seagal's Atari ST Web Site

Steem

"Hard To Fix"

  Coming soon! Features, fixes, hacks, etc. for Steem SSE 3.5.1.

 

 
     
 

Warp

 
 

 
  Another quality Thalion game (Pasti image of the original) now working in Steem.

This game really warps the CPU around, trying to fool emulators (or crackers at the time...).

Note that there are wrong Pasti images of the game floating around, including the image at the Thalion shrine site.

The version here is correct.

 
     
 

Blood Money

 
 

 
  Long marked as unworking, this bloody game will now run in Steem in its original version, Pasti (STX) as well as Kryoflux (IPF). You may bet your money on it.

This is just another hack in exception handling (like for War Heli) but we're looking at more general emulation too.

 
     
 

Exception Stack Frame

The Blood Money issue made me think and experiment further about this problem of having to adjust the Program Counter (PC) for some CPU exception cases.

Here's the result, that should be integrated in next version of Steem. It's no authoritative text, it's limited and speculative but it's the first real essay on the matter AFAIK: Program counter and exception

And related to it (from another development page, it may help): Prefetch

It will only interest a handful of people though!

All you need to know as Steem user:

In Steem SSE (beta), exception stack frame is now handled in two ways:
based on opcodes if option 'Hacks' is checked. This is the more robust way.
Based on a general theory if that option isn't checked. It works with known
cases but could break some programs. It is the 'fun' way.

If you get a "fun" crash without option 'Hacks', try with 'Hacks' on.
 

 
     
 

War Heli

 
 

 
  Argh! War Heli is one of the cases for the exception stack frame problem, so of course I ran it as part of some checks, that's when I realised that "accurate" drive emulation fixes for v3.5.0 had a liitle bug that broke the game in slow mode which is the recommended mode. It still worked in fast mode but then you must endure some garbage on the screen while it loads. Fixed in v3.5.1

Notice how I deal with my adversaries.

 
     
 

Overdrive / HD6301

 
 

 
  Argh! In true HD6301 emu mode, the spaceship didn't show on the menu of this interesting demo (but you could make it appear).

It was because of a mistake in ACIA double buffer implementation. How it produced this result I still don't know.

Fixed in v3.5.1... maybe! now what else is broken?

Update: there's also the problem of non-responding keyboard when coming back from a demo. Current build, works in true 6301 mode.

 
     
 

CPU/MFP/DMA speed in STE mode

 
 

 
  To obtain more satisfying values in a hardware test devised by ljbk (AF), two adjustments were necessary:

1) Use the same frequencies for CPU and MFP on the STE as on the STF.

2) More precise MFP timers when the delay is very short (doing a TODO of Steem 3.2 in the process, hey it looked complicated but it was simple!).

It could result in better DMA sound.

 
     
 

Star Trek (TOS1.00)

 
 

 
  Space... the ultimate Frontier... The sound samples of this game are extremely hissy in all emulators. I'm working on this but when I manage to reduce the hiss (aliasing?), there are more prominent cracks!

The sample filter triggers only if both PSG Filter and Microwire options are checked. It's like that!

 
     
 

Scanlines Interpolated

 
 

 
  I said I wouldn't add features on the current video rendering system, because the future of Steem could be other libraries like Direct3D or SDL, and also I prefer the crisp rendering, but this was requested several times, and it probably looks more like a real ST screen. In fact I like it very much now! The mode just combines the features of 'Stretch' and 'Scanlines'.

It was a quick addition/hack, I just hope it won't ruin previous fullscreen debugging (the feature works in windowed and full screen modes both).

 
  Here's the difference that it makes:  
 

 
 

Usual scanlines

 
     
 

 
 

Interpolated

 
     
 

 
 

Feels a bit more like a ST

 
     
 

Disk drive emulation: improved

 
 

 
     
 

Microprose Golf

 
 

 
  Hack? Fix? Still wonder. It's based on explanations by Petari. Works in 'slow disk' mode now. Note that the STX version won't work, but when a correct IPF version is released it will.

Update: now works without special hack but it is extremely slow. Update: see below.

The game is password-protected anyway. Update: see below too.

 
 

 

 
 

Noughts and Mad Crosses (STE)

 
 

 
  Argh! The demo stalled at this screen in v3.5.0. Fixed in v3.5.1, slow disk mode.  
     
 

Drive Info on screen

 
  While debugging the drive emulation of Steem, wondering if some program loads or is stuck, this was the opportunity to add a nice feature, showing on the display current drive, side, track and sector.  
  The new option is here (not in SSE tab):  
 

 
   

So you launch Microprose Golf and it takes much time (I'm aware it's a bug...):

 
 

 
   

At least, you know it's still working somehow: it's reading (green led) on drive A:, side 2, track 29, sector 3, while a scroller informs you which emulator is the best just in case. The title screen finally appears, the silly music plays:

 
 

 
  Update: the slow loading bug has been fixed. Now the game loads at the same speed in Steem's "native" drive emulation as in CAPS emulation, with a noticeable slow down when the music plays. It's because the drive is missing the sector all the time and must spin more.

If this isn't emulated, the game will crash, how exactly I don't really know, the fix is mainly based on Petari's explanations.

 
     
  OK, it's working, but what about the password? Not to worry, I also made a patch that will make the following -or anything or just return - be accepted (childish I know):  
 

 
  Update: this patch didn't really work, it passed that screen but that's all. Fortunately Petari made a working patch (it's more his business), that will be included in the game download file.  
     
     
 

Magnetic Scrolls loader

 
  I still remember this dude that had an electronic gadget attached to his ST, giving on big red leds the track info. So he showed me how his ('hardcopied' :( ) disk of The Pawn was reading the tracks backwards (here the Pasti version):  
 

 
  Now we can check that in Steem, and we get sector info to boot. Notice the high number (beyond doc spec), it's part of the protection scheme.

Yeepee!

 
     
  Now, colour of digits matches drive led, so you may use track info only.

If there's an uproar I'll change that again.

Here The Guild of Thieves original (IPF):

 
 

 
   

And here another version, hey look it's a fake, it loads normally! There's also no copyright.

 
 

 
     
     
 

Notator

 
 

 
  Well there was a request for this, delayed for a bit, what's the point? But since I was trying to improve ACIA emulation, which is a chip transmitting information for the keyboard as well as MIDI, why not check it, and surprise, the great ST sequencer by EMagic works better in v3.5.1.

Will it be able to record the guitar play of Steven Seagal?

 
     
 

ProCopy

 
 

 
  What you always desired is now reality: in Accurate disk access mode, Steem will be able to Analyze (F9) a regular disk image without hanging. Note that Steem 3.2 already could make a working disk copy using the Protect option (F5) of ProCopy.

Analyze also works on IPF disks, but not STX. Also, you can use ProCopy to copy some IPF disk images to normal ST disk images, again not STX.

With this latest fix, all in all and excepting bugs, floppy drive emulation has much progressed again between v3.5.0 and v3.5.1. Care has also been taken to leave emulation unchanged in fast drive mode, so we shall break nothing essential just in case.

 
     
 

Pasti revisited

 
  In v3.5.1, toggling Pasti on/off in the disk manager will not force a reset anymore, nor eject the disks.

The reset thing has always annoyed me, and it keeps you from doing some experiments.

The price for this is: you're responsible, you must know what you're doing. There's no real "risk" anyway, so this is all fine.

Update: it ended up  being a bit more complicated than that as one must eject disks then reinsert them (this is transparent).

No error message if you go native with a STX disk in, or Pasti with a DIM disk in, the disk will just disappear.

 
     
 

Death of the Clock Cycles

 
 

 
  Argh! The fix for Aladin was too generic and broke Death of the Clock Cycles in v3.5.0.

Now it won't hang after its 27907 exceptions...

 
     
 

Disk Image Name

 
 

 
  Just had the idea, so why not? It's another time the 'scroller' function (mis)used.

I like it. If you don't, the option is there.

 
 

 
     
 

Sentinel revisited

 
 

 
  Well folks, recognise this screen? This is Automation 001, when it was still called LSD/Was (Not Was). There has long been a problem in Steem with the 7th game, Sentinel.

In fact there were two problems, a slow mouse issue, already fixed since v3.4, and a stranger issue where the mouse was stuck on the bottom of the screen, which only existed in this version of the game, and only in TOS1.02.

Running some tests I realised that...

 
 

 
  Just what you've all been waiting for, as of v3.5.1, the Automation version will also work provided you select slow disk drive option. This is correct emulation.

That was the problem, who would have thought?

 
 

 
  Another screenshot to celebrate the closing of a quite frustrating case.  
     
 

Hades Nebula

 
 

 
  Argh! There are some ACIA/IKBD difficulties with this game, and it was broken since v3.4.

Hopefully fixed for v3.5.1.

The game isn't great animation-wise, but the music is cool.

 
 

*** I thought that was it for v3.5.1 but... ***

 
 

Preselect RAM

 
  Since many STE-only games or demos prefer more memory, RAM will be set to 2MB min when switching to STE model. Easy, useful. And 1MB when going STF will be the most compatible. So it defaults to a 1040 STF. Hey maybe you only had a 520 ST, now you're RICH! Of course you can still change it at your convenience.

With that and auto TOS selection, you're in your armchair, just pick a ST and run the program.

 
     
 

Pasti revisited again!

 
  Also, to make life easier with Pasti, the disk manager should be smarter, displaying all images Steem can handle, and enabling or disabling Pasti as needed. For example, you have Blood Money in IPF and STX format, in zip, rar or not. You can see them in the disk manager, and run them. You can run the Union Demo in STX format, then the BIG Demo in DIM format, and so on, without changing the option. The only time you need to change it is when you decide whether your ST and MSA disk images are run by Pasti.dll too.

After that we go even further, with a new SSE option:

 
 

 
  Err yes? you may ask. If we don't want to use Pasti for ST and MSA, we just don't select it in the disk manager, right?

Right. Except that with this option, you can now mix STX disk images in one drive with native or IPF emulation in the other drive. Concretely, you can ProCopy simple disks from STX to ST (tested with MPS Golf).

I'm now confident that native Steem drive emulation has better timings than Pasti for simple disk images. The option is there because the technique used may be a bit... unreliable (imagine, when do writes to various chip registers must be handled by Pasti or by Steem?)

 
     
  So instead of debugging I added more features! ST enthusiasts will report how successful this was...  
     
 

Scanlines Interpolated: med res

 
  Almost forgot this, but didn't, also in medium resolution you get the new display mode combining scanlines and "stretching". You may also like the result, or not, it's kind of realistic, less crisp.  
 

 
 

Original scanlines, crisp

 
 

 
 

New display mode, a touch blurry

 
     
  We need to be careful, some games like The Pawn (again this one!) mix low and medium resolution. The new display modes are based on little hacks, they won't work yet in such a case, so we need to detect and disable the feature.

In The Pawn, you may "enjoy" the interpolated mode for the text...

 
 

 
  But when you draw the picture, it gets crisp all of a sudden!  
 

 
  Hey, don't complain, at least you avoid this:  
 

 
  Maybe in a later version we try to fall back on 'normal' scanlines.  
     
     
     

 

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