I worked at Univac Defense Systems in the early 70's. The launch control
computer for the Minuteman was made by Univac. It had plated wire memory. I
remember when the failure analysis group had to analyze a module that failed in
the field. The module was locked in a safe and someone had to boost their
clearance level to work on it. In plant 1, in Saint Paul, MN near the
Mississippi River, there was a thin film memory production facility. It
produced the memory used in the S3A submarine hunter (an/ayk-10 if I remember
correctly). The bit planes were made from etched glass that had metal sputtered
onto it, with tons of tiny holes for the word wires. The bit planes were
stacked and the word wires were threaded through the tiny holes perpendicular
to the planes. Because I sometimes worked out of plant 1, I had to take safety
training for hydrofluoric acid which was used to etch the glass. Nasty stuff.
