device drivers:
<ul>
 <li>doesn't have a "main"
 <li>like a library in the sense that it doesn't have a main.
</ul>

<p>
why timing is important, e.g.  atomic operations: webcam, etc..
mv of single file on same filesystem and ln versus cp.
<p>

timing for sampling (e.g. radar, our sound system, constant sampling rate)

<p>
reading from devices, e.g. analog to digital converter example
(as in sample and hold)

<p>
atomically reading a 64 bit register (e.g. RTC) into two 32 bit variables.

<p>
<a href=jit_hack>Just In Time hack</a>: jit_hack.c
<br>make
<br>insmod jit_hack.o
<br>cat /proc/jithack
<br>dmesg