On 17 Nov 2008 at 10:29, Reid Allen wrote:
Norpak was a logic device that used only 'NOR'
gates. It preceded the
PLC concept. The gates were hardwired. Since any logic function can
be created using negative Boolean operators (NOR or NAND) they were
usable for solid state control systems in place of relays. We used a
Norpak system at the San Francisco International Airport on a plane
fueling system in the middle 1960s. They had 10 NOR gates per module,
and we wired modules using something like #20 AWG wires with some kind
of termination on the end that could be inserted into the Norpak
units.
One had to be very careful using the units because after the various
functions and their arrangement had been designed there were often
redundant gates in series that could be eliminated, but this caused
transparency of design to be lost.
I was working for the Standard Oil Company of California in those days
down on 225 Bush Street.
I think your post is in reply to a July 2002 posting:
http://www.classiccmp.org/pipermail/cctalk/2002-July/003701.html
Don't worry--timeliness doesn't seem to be a feature of this list!
NORPAK (the way Square-D writes it) modules occasionally show up on
eBay. Right now, there's a 1967 catalog and two modules (a time
delay unit and a signal converter). The Square D website gives the
year of introduction as 1958.
Cheers,
Chuck