🚀 go-pugleaf

In article <92245.122042A10742@TRMETU.BITNET> A10742@TRMETU.BITNET (Pinar Aydemir) writes:
>I almost hear everyday that msdos is non-reentrant.
>It is non re-entrant so dont call a dos funcion from a Interrupt Service
>Routine.
>Since It is non reentrant, bla bla bla.
>
>I looked at some books about OS, and the definition of reentrancy is
>given as being unmodified (pure) code.So, what makes msdos non reentrant ?
>Any information  is appreciated.
>-Yasemin

For any program/function to be reentrant( i.e. recursion of sorts ), The code
must save separate copies of the local variables.  Dos only saves one copy
of it's variables, and all the functions have access to them, so if you were
to call a dos function from an ISR, you would more than likely be clobbering
data for a previous interupt.  There are probably some interupts that are
safe to call more than once, I thought I read about an interupt that would
tell you if it was safe to call other interupts( not sure on this one)...

-- 
    - Zach Heilig (heilig@plains.nodak.edu)

Ninety-Ninety Rule of Project Schedules:
	The first ninety percent of the task takes ninety percent of
	the time, and the last ten percent takes the other ninety
	percent.