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

[Chris Jenks]

   Dear Group,

   I'm writing a C program on my Debian system to read from an interface 
board through the parallel port. I need to wait at least 300 microseconds 
before reading from the next channel, to give the A/D converter on the 
board time to stabilize, but I don't want to wait much longer (e.g., 10 
milliseconds) because it will make the program too slow. The delay 
functions (usleep, nanosleep...) only provide delays down to 10-30 
milliseconds, despite their name, because they apparently yield the CPU to 
other tasks with every call. The best solution I've found it to read (or 
write) to a port (e.g., 0x80), which takes one microsecond. By doing this 
300 times, I get something close to the wanted delay, plus a little 
because of time sharing, but it is good enough. The only thing I don't 
like is that my process takes about 97% of the CPU, even though it spends 
almost all its time waiting. The CPU is a fanless 386, and it runs pretty 
hot at 97% usage. Is there an elegant solution to this, or should I look 
for a CPU fan? I would like to leave this a time-sharing system.

   Thanks,

     Chris