[vox-tech] Must a 300 microsecond delay keep the CPU busy?

[John Wojnaroski]

Chris Jenks wrote:

>
>   Dear John,
>
>   That sounds like the best solution. The A/D IC does have an End Of 
> Conversion pic that I can connect to any of the parallel port inputs. 
> I'm relatively new to C. Do you know of a function I can cell that 
> would wait for an interrupt from the parallel port, or is it necessary 
> for me to write one?
>
One more thing;  perhaps just a matter of semantics, but perhaps worth 
noting.

You don't "wait" for an interrupt...  an interrupt is a signal to the 
CPU to stop what is is doing and "answer the phone".  When the interrupt 
line is raised the CPU reads the vector (value of the interrupt), saves 
the machine state, executes the ISR (Interrupt Service Routine) for that 
vector, restores the machine state, and continues processing.  If you 
really want to get into the details and "down and dirty" might suggest a 
book by Rubini on writing Linux drivers, available on the web or any 
number of on-line book stores.

JW