🚀 go-pugleaf

I had a summer job operating the EMCS (Energy Monitoring and
Control System) at Fort Ord (CA).  It consisted of two HP 1000's
connected by a proprietary interface, and hundreds of Z80 based
field units.  Typically, one HP 1000 did the processing and the
other handled communication with the field, although either could
be run by itself and handle both jobs.  The field units had a
battery backup that lasted roughly 30 minutes, after which they
had to be reinitialized by the master HP 1000(s).

This worked great, unless the entire base lost power for more
than half an hour, and this happened at least once or twice a
summer (typically a garbage truck driver would leave the forks up
and snag a power line).  All the field units would exhaust their
backup power, and need to be reinitialized.

Once power was restored, the reboot sequence would start
initializing the field units.  While the field units were running
some sort of self diagnosis, the master system would start
initializing more field units.  Later, when the field units
started reporting back to the master system, the HP 1000 handling
communication would get overloaded.  The other HP 1000 would wait
for its partner to acknowledge a message, then timeout and reboot
the system.

The only solution was to turn off scanning on all the field
units, but by the time the terminal I/O routines were started
there was only time to turn off scanning for about half a dozen
field units before the imminent reboot.  It usually took two of
us an entire day to disable scanning on all the field units, and
then it took me a couple days to restart scanning one field unit
at a time.

Darin McGrew			mcg...@Eng.Sun.COM
Affiliation stated for identification purposes only.