All cars since 1994 in the U.S. have had built in data acq
 through what is known as OBD II. OnBoard Diagnostics.
 You can monitor what is going on in real time.
 Here is a sample of the data out of my Cougar 4.6L V8
 climbing a hill near my house. I gathered this
 data with  a note book computer running Windoze through the RS232
 and CarComp software. Note the first column is time.
 I think the last column is a bit suspect as it is supposed to be
 a calculated percentage of power what ever that is.
 Perhaps max power available at that RPM.

 The new RX8 must have this OBD stuff so perhaps we can take
 advantage of it somehow.

 About a dozen different parameters can be monitored in real
 time with the right software. The car computer must output
 this as well as manage the engine EFI/IGN and all the smog
 stuff as well all in real time.

 Paul Lamar

[Todd TC. Carrico]
While I am a fan of Windoze (Sorry Paul) I would question any software
claiming to be "Real Time" on a PC.  Even Linux has issues doing real
time.

Different world this Real Time thing as opposed to the Windows Time
thing <grin>.

tc

It is true the the Intel 80Xxxx processor architecture is not determinant.
Other processors like the 6502, PIC, 6800 and 68000 are.
Long story and I won't go into that here.

It depends on how you define real time. The quality is the percentage off 
your target time your software and hardware can achieve. For example if the 
software is designed to go below the operating system directly to the hardware 
it is more real time  than if it had to go through any operating system. 

If you write your software in Visual Basic it is not going to allow
you to go under the operating system. If you write your software in
C depending on the C compiler you use it may allow you to go under
the operating system. Probability is high that assembly language 
will always allow it. Quick Basic allowed it in DOS and in fact
encouraged it with certain real time features like PEEK, POKE,
IN PORT, OUT PORT, ON TIME and ON COM. Power BASIC for DOS took
that one step further with an inline assembler feature although
it did not have the smart editor of QB.

Many high speed animated computer games go under Windows. In other words 
they roll Windows out of RAM to the hard disk and run directly on the processor. 
When you exit the game they roll Windows back in to RAM from the hard disk. 
This is why they are so easily ported to Linux and why so many of 
them appear to run on Linux.

DOS is far more real time than any multitasking OS like Windows or Linux 
as it is easy to go below the OS directly to the hardware. Having said 
that it is possible to get a real time version for Linux that runs 
under Linux while still using Linux service facilities.

http://www.realtimelinux.org/

Paul Lamar
 
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