
                             Questions About !STem
                            =======================


Q: Why isn't the emulator multi-tasking like many other RiscOS programs?

A: Emulating another computer requires an enormous amount of processing power.
   For each emulated instruction, around 500 to 1000 ARM instructions need to
   be executed, so even with a StrongARM processor the emulator will be much
   slower than the real machine. Multi-tasking would reduce the speed even
   further, making the emulator impossible to use.

   Hopefully, within the next few years, the necessary processing power will
   become available to make STem fully multi-tasking. Already I am re-writing
   bits of the code so that the transition can be made as smoothly and quickly
   as possible.


Q: Why is there a border around the picture displayed on the monitor?

A: On the Atari ST screen resolutions of 320x200, 640x200 and 640x400 are
   possible. If the exact resolution is not available on the Acorn computer, the
   emulator will try it's best to use a larger resolution, and to center the
   picture on the screen. In this way it ensures that the picture is always
   viewable.

   To remove the border you will have to define new resolutions, with the sizes
   given above, and place them in your monitor definition file. You should only
   alter your monitor definition file if you are sure what you are doing.


Q: Why is it recommended that video RAM is fitted to the host computer?

A: The emulator is very slow compared to the real computer, and anything that
   can be done to speed it up is desirable. Having 1Mbyte of video RAM fitted
   is sufficient to reduce the amount of data being transferred over the data
   bus, hence leaving the bus free for the processor to use.


Q: Why aren't TOS images distributed with STem?

A: Although the Atari company no longer exists, their operating system is still
   copyrighted, hence it would be illegal to give copies away without their
   permission.

   If you have no moral concerns then TOS images can be obtained easily on the
   Internet, and of course you could always buy a cheap second hand Atari ST and
   make your own copy.


Q: Why will STem only work with certain versions of TOS?

A: Additional hardware is needed to run TOS versions 3.00 and greater. STem is
   not yet able to emulate these pieces of hardware, so those operating systems
   which rely on them will not work. Gradually, some of this hardware will be
   implemented, but this could take some time.

   There should be no problems with TOS versions 1.00, 1.02, 1.04, 1.06, 1.62
   and 2.06. There is an unknown problem with TOS 2.05 which means that it
   doesn't always boot correctly..


Q: Why do some keys on the keyboard have no effect when they are pressed, and
   others cause the wrong characters to be entered?

A: Detecting keypresses on the Acorn keyboard has to be done at a very low
   level, and a certain amount of translation is required to convert the
   keypresses into a form which the Atari operating system expects.

   Different translations are required for non-English Acorn keyboards, and also
   for non-English versions of TOS. As I do not have access to all possible
   keyboards and TOS versions, some of the translations will be incorrect,
   resulting in the wrong data being sent to the Atari operating system.

   The punctuation keys (and the UK pound sign) are the most likely to be
   affected, because their location varies so much with different keyboard
   designs.

   If any problems are experienced, please contact me via email, and I will do
   my best to make the necessary modifications to the emulator.


Q: Why is there no sound support?

A: I have done some trial sound output, but my general feeling was that the
   emulator is just too slow at the moment for me to even consider releasing
   any sound code. The emulator cannot generate interrupts fast enough to allow
   software control of the emulated sound chip, so all sound output is very
   corrupted.


Q: Is STem available on other platforms?

A: No, and there are no plans to port it in the future. Most of the code in the
   emulator is highly RiscOS/ARM specific, and considerable effort would be
   needed to modify it for other systems.

   There are several other Atari ST emulators available for Unix and Windows,
   with STonX and Pacifist being the best in my opinion.



!STem is  Copyright Samuel Ellis, 1998.
