Frequently Asked Questions
Q: Why is it MS-DOS based?
A: So timing can be done with the accuracy required. Windows95/98/NT/XP/Vista
are multi-tasking operating systems, but they are NOT hard real time
systems. This means that you cannot always rely on them to do things
when you need it to be done.
Fortunately, Windows 95/98 both have a native DOS mode, so operating system support is not an issue. During the event, exit to DOS mode to run Accucros. If precise timing is not needed (i.e. while running reports or doing driver registration) you do not need to exit to DOS mode.
Q: Can a PC really time to
1/1000 of a second?
A: If programmed correctly, yes. It isn't simple and this is one
thing that makes Accucros really unique. You have to take control of
the PC's counter-timer hardware and write interrupt routines that
can read the state of the triggers. You also need to use an
operating system that allows you this level of control, which is why
DOS is used.
Q: How many people need to be
trained to use Accucros?
A: One person should be familiar with Accucros before the event. The
mouse-driven interface makes Accucros the easiest system to use by a
wide margin. With Accucros you won't have to remember hot-key
combinations or constantly be reading the screen figuring out which
number to press to navigate to different screens. Instead, you can
train people DURING THE EVENT and have them using the system within
minutes. There have been several cases of clubs getting Accucros and
using it the next weekend without trouble. This is one other thing
that makes Accucros unique.
Q: Can you give me more
details about timing?
A: Think of Accucros as a program that turns your PC into a
dedicated controller.
With DOS you have complete control over the PC timer/counter
hardware, so you can perform some hard-realtime actions (like
reading triggers). The triggering subsystem is interrupt driven,
using interrupt 0 (the highest priority interrupt). Things like
printing and editing run times are done non-realtime and are
interrupted by the trigger detection routines. The user won't ever
notice this.
You could load some weird TSR program that disabled interrupts for
over .0005 seconds, which would cause timing to be inaccurate. I've
heard that some data compression and networking software can do
this. For this (and other) reasons you need to load pretty clean in
your config.sys and autoexec.bat files. I suggest only loading the
mouse driver and loading DOS "high" to maximize memory.
By the way, in industry using a PC with DOS to perform hard-realtime
actions is common. It's just most at home, non-programmer PC users
don't realize this. I constantly hear that "PC's can't time to .001
seconds", and the only proof offered is that the heard it from
"someone who knows", or that they have to reset their PC time
occasionally. It's not difficult if programmed correctly. In fact, I
could increase the timing resolution even further.