Mail Archives: djgpp/2001/03/31/22:17:28
Thanks Eli for the answer !!
>I suspect that Int 8 is hooked by DOS and perhaps by some other
>resident software (depending on your CONFIG.SYS and AUTOEXEC.BAT).
>However, if you run the system with IRQ 0 disabled and you don't see
>any adverse effects, you probably shouldn't worry too much.
You're right. I'm using the most clear DOS boot (IO.SYS, MSDOS.SYS and
COMMAND.COM). The only problem I see until now is the freezing of the
internal
date & time. There is no device driver loaded that could be using INT 8.
>You can read the time from the CMOS clock (which uses an independent
>timer chip), and then set the system clock with a call to the library
>function settimeofday.
>Function 2 of Int 1Ah returns the time of the CMOS clock; look up the
>details in Ralf Brown's Interrupt List.
Great ! I know that BIOS copies the data from the RTC (Real Time Clock -
CMOS
clock) during POST, and after that, the BIOS don't use it anymore. I need
only
to copy the date/time back.
>> PS: This real time application is giving me so much headache that
>> I'm planing not to use MS-DOS anymore. I started to think about
>> using Real Time Linux, QNX and some stuff like that, just to get rid
>> of the problems with the code timming and CPU dedication.
>
>DOS is indeed not an ideal RTOS, but please note that 50-usec timing
>is something you will most probably have problem with on any OS,
>including QNX and RTLinux.
My friend, these are the words i was looking for !!!
Until now, I didn't find any good comment about these RTOSes concerning
their
timing resolutions. I didn't know, for example, if RTLinux can have a task
running at exacts 50usec with no problem...
I will stop thinking on porting the software to RTOSes for now...
Using DOS i have a good control of what the CPU are doing in each time step.
My only problem is the precise measurement of the CPU clock since i'm using
the 64 bits Pentium TSC counter to calculate my loop timmings.
Thank you for all
Eduardo TUDA DocHell Lorenzetti Pellin
PEA - Electrical Energy and Automation Department
USP - Politechnical School of Sao Paulo University - BRAZIL
http://www.pea.usp.br/~epellini
---------------------------------
And if you have a time to loose,
an open mind, and right to choose,
would you care to take a look,
or can you read me like a book...
time's is allways on my side...
--------------------------------- (Up the Irons !!!)
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