Starts the Long Period Zen Timer counting. Once you have started the timer,
you can stop it with LZTimerOff
or you can latch the current count with
The Long Period Zen Timer uses a number of different high precision
timing mechanisms to obtain microsecond accurate timings results
whenever possible. The following different techniques are used depending
on the runtime environment and CPU on the target machine.
If the target system has a Pentium CPU installed which supports
the Read Time Stamp Counter instruction (RDTSC), the Zen Timer library
will use this to obtain the maximum timing precision available.
If the Pentium RDTSC instruction is not available, we then do all timing
using the old style 8253 timer chip. The 8253 timer routines
provide highly accurate timings results in pure DOS mode, however in a DOS
box under Windows or other Operating Systems the virtualization of the timer
can produce inaccurate results.
Because the Long Period Zen Timer stores the results in a 32-bit unsigned
integer, you can only time periods of up to 232 microseconds, or about 1hr
20mins. For timing longer periods use the Ultra Long Period Zen Timer.