[net.micro.pc] Real-time on the PC-RT?

cynader@dalcs.UUCP (Max Cynader) (03/07/86)

     We just got back on the NEWS network, so sorry if this
is a repeat of other questions.

     I am thinking about buying a PC-RT to run some
experiments in my lab. But I am concerned about using
UNIX to collect realtime data. I would appreciate hearing from
anyone who has experience or knowledge in this area.

                       Thanks in advance
                          Kathy Murphy


UUCP: {utcsri, ihnp4!dartvax}!dalcs!cynader
CDN:  cynader@cs.dal.cdn
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lee@haddock (03/13/86)

It depends on the nature of the sensing device and the need for the Unix
program to respond to real-time input with real-time output.  For example,
if the requirement is just to absorb high-speed asynchronous line data,
the RT will work very well; the machine can take several lines at full speed
without losing characters.  However, if the Unix program must respond in real
time with control information, the RT does not improve on Unix's inadequate
real time behavior.  There are, in fact, even more sources for real-time
delays in AIX than in other Unix systems, due to VRM low level processing of,
for example, 286 coprocessor board handling.