Re: Multitasking theory question

[Ted Dennison <dennison@telepath.com>]

Kai Schuelke wrote:
> during my programming course we learned about tasks, too. One qustion that
> couldn't be answered was:
> 
> Is an Ada-Task a process of the operating system or is it a kind of process
> inside the whole program?

How tasks are implemented is up to the compiler. If the OS has support 
for lightweight processes (processes that share a global memory space 
with each other, aka "threads"), then the compiler usually implements 
tasks using those. If not, then typically it will simulate them within 
the program's process.

I've even seen one compiler that implemented tasks using heavyweight 
processes and a shared memory section (this system broke down if you 
ever called a non-Ada routine that allocated memory).


> Under DOS tasks ran cooperative, under Win preemtive. Why this difference?
> Is it because of the OS, the compiler or the change from Ada83 to Ada95?

DOS has no process support of any kind, Win32 supports threads.