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Steem Engine v1.2

Shiuming Lai gets a new Atari computer

All right, I'm cheating - what with the imminent threat of Christmas looming upon us, the last thing I can afford is to splash out on a new computer for myself, so I did the next best thing and grabbed hold of a freeware emulator.

The Steem Engine (STE-EMulator) is a brash young upstart on the Atari ST emulation scene, developed by two brothers initially as a joke to see how far they would get before failing. As it happens, they have been doing very well and the project is rapidly gaining momentum. We're already on the third release (note: just as we went to publish, v1.3 was released), now implementing MIDI support, and programmers can download a debugging tool to assist its development into a more faithful emulation.

Practicalities of emulation
Different types of emulation exist to serve the varying needs of users. Some only give operating system level emulation, using a largely compatible OS standard, maybe with enhanced functionality. For example, a PC (or Mac) running the appropriate version of MagiC can execute cleanly-programmed Atari software with higher screen resolution and colour depth based on the host's hardware ability, and integrate an Atari environment with other systems. It's possible to effectively access network volumes, DVD-ROM content and massive partitions as if they belong to the Atari OS, even share them with the native OS.

On the other hand, there are complete system emulators like Steem. Here, the OS functionality is achieved by using binary images extracted from the actual TOS ROMs fitted to real machines, defining the "official" capabilities. At the same time they emulate the hardware, for software which bypasses the OS to side-step its limitations. To all intents and purposes, this type of emulator is intended to give you a logical replica of the real thing, warts and all. You have the GEMDOS capacity limitations, so don't try manipulating huge files on your PC's hard disk directly from Steem, that's asking for trouble!

Emulators of the latter type are unequivocally aimed at game and demo connoiseurs, where hardware-level emulation is essential as most such software is extensively hard-coded for performance.

Like all emulators, Steem has to know where to find resources. First time it's started, it prompts you to select drives for its file system (either real Windows drives or disk images, more common for games), which TOS image to use and so forth. I find disk images a bit of a nuisance, though this is no fault of any emulator programmer. PCs are simply not as flexible as Ataris when it comes to floppy disk drive handling (program an Atari to access track 90 of a DD floppy disk and it will have a good try!) so extended formats are out, as is trying to run most commercial games and demos straight from floppy.

Further fine-tuning can be done after the initial configuration. One of the things I really like is its screen handling. Different draw modes are available to suit the power of your PC (update 1, 1/2, 1/3 or 1/4 frames...), as well as full and windowed mode. The latter is implemented with a superb real-time scaling routine that renders the display with anti-aliasing, plus a snap setting for nice and sharp integer-scaled output. Aspect ratio is accounted for, with horizontal line-doubling to avoid ST medium resolution looking like a panorama. Steem can be associated to the popular MSA (Magic Shadow Archiver) image file format or memory snap-shots.

How to spot an emulated ST
One of the first give-aways that an ST environment is not the real thing is the mouse pointer movement. Particularly on PCs under Windows 9x, where the PS/2 mouse tracking has a very low sample rate and looks jerky no matter how fast the processor. I've got a Microsoft PS/2 mouse, with Intellipoint software on my Windows 98 SE installation, giving very smooth movement in its native environment (and MagiC PC), but doesn't improve things for Steem. In fact, there is also a tracking latency which makes the cursor feel like it has inertia. Seasoned Atari users accustomed to the razor-sharp mouse handling of their real TOS machines will either get motion sickness or feel frustrated as they have to compensate by reducing their control speed to a snail's pace. STew! 1.0 (another new arrival, but not STE-specific and based on the source code of veteran emulator, WinSTon) is rather better in this respect.

Another tell-tale sign is the system noises. Speaking to a colleague on the telephone some time ago, I heard a familiar noise, the ST key-click. However, it didn't quite have the same tone to it. "That's not a real ST. You're using MagiC Mac, aren't you?" I said. Steem's whole PSG and DMA stereo emulation is not yet anywhere near complete and this is reflected in the sounds (key-click included) or lack of them in places.

On with the testing
Originally I had the bright idea of zapping my Mega STE's hard disk contents over to the PC by network, as Elmar Hilgart in Germany was due to send me a review sample of his Ethernet adaptor. Murphy's Law did a good job of making sure this arrived too late so I resorted to Sneakernet. I could have used a CD-ROM compilation but felt the best way to test was with software I'm familiar with. Some of the pictures here give a taster of what's possible with Steem. Rather than write a long compatibility list which is bound to improve, I will just say if it worked, it worked well, except for the sound as mentioned above.

Remember those ST games which were a tad sluggish? Steem has variable clock speed emulation, all the way up to a heady 128 MHz (nice that it's so precise, whereas some other emulators just run as fast as the host allows with no indication of relative speed). GEM is satisfyingly snappy though my attempts to augment that by installing NVDI 5 have failed so far. Interestingly, the extra speed doesn't accelerate all games. Those that it did exhibited dramatic improvement.

For a moment I had manic visions of becoming a MIDIMAZE 2 death-match champion as this great network game thundered along at a fantastic rate. Sadly, my Mega STE and PC would not talk to each other, both thinking they were playing solo. Russell Hayward, co-author, confirmed to me, "At the moment MIDI only works to musical instruments, it uses the Windows multimedia system to send it through, not direct to the hardware."

Yes, the MIDI does work for musical instruments, I got one sequencer and a handful of file players to work. Definitely no replacement for the real thing!

Steem's stability is generally very good. However, I did experience frequent host system freezing in ST monochrome mode, at various speeds past 1 GHz (using an overclocked PIII 933EB processor which is otherwise perfectly stable and actually running cooler than it did before I made any modifications, when I clocked it at factory specification). I got the same problem with TOS 1.02 and TOS 2.06 images, and this was with Windows 98 SE. No such problem with Windows 2000 (SP1), yet. At first I suspected the latter OS was fine because it doesn't yet have a driver for my default audio card, so I switched over to my Creative SoundBlaster Live! 1024 "joystick-card" in the Windows 98 SE test environment, but still no difference. The real to logical (emulated) I/O device mapping initialisation clearly occurs before this mysterious freezing (which typically manifests during the GEM loading stage or soon after that once on the desktop).

If development of Steem continues at its current rate I've no doubt it will become the first choice in virtual STE computing for PCs. Even in its current form, it's well worth the download, you'll be up and running in a matter of minutes. Only by many people using it and giving feedback will it progress towards its ultimate goal.


Steem's fancy on-screen display. The media access indicator
is a nice touch.


Microdeal's Concerto MIDI sequencer. In principle it works,
but the timing is incorrect (not surprising).


Now that's what I call a processor upgrade!


One of the ST's very best racing games. I bought a copy purely
on the basis of watching this fantastic intro animation in a
shop, which one should never do.


Here's Stardust, a top STE/Falcon-only game. Only the sound
isn't all there.


Even undocumented screen modes with overscan and palette
switching are attempted. Pinball fans will have to wait with
baited breath to see if Obsession will ever work, though.


Kick smiley butt: Using Steem, you could run rings around
everyone in MIDIMAZE 2, if only the MIDI link would work...


A pretty lethargic game on a real ST, no better at full-Steem
ahead, but really zips along on the rival STew! emulator.

 

Glossary of terms

  • Sneakernet
    Before the advent of high-speed local area networks, the quickest way to transfer files from one computer to another was to save them to floppy disk, put on your sneakers and make a dash to the destination computer!

 

 Summary

 Product

Steem Engine 1.2

 Authors

Anthony and Russell Hayward

 Download

http://steem.atari.org

 Requires

Windows 9x or 2000 Professional (Me and NT4 not tested) and compatible multimedia sound card for MIDI I/O

 Price

Freeware

 Pros

  • User-friendly
  • Active development
  • Speed and  control

 Cons

  • Sound emulation needs a lot more work as does the mouse and keyboard input

 Score

* * *


MyAtari magazine - Review #4, November 2000

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