This discussion caught my eye and I did some quick Web searching. PX23_1103A_sysMaint_Feb57.pdf at bitsavers.org under "pdf" and "univac" and "1103", has general descriptions of Univac 1103 modules, or in their terminology "unit chassis". There's a single photo of a chassis, which clearly is of the same kind as the module in discussion. I believe it states there are 86 kinds of unit chassis. This manual is dated Feb 1957 from "Remington Rand Univac". The manual PX71871_ERA103vol2sec4.pdf has on page 1 and many other pages, "Remington Rand / Engineering Research Associates Division" Page one adds "(street) St. Paul Minnesota". That confirms the "ERA" identification of the VCFed's module. This manual has text descriptions of various (vacuum tube) circuits, I/O and memory elements. Seems to be a kind of primer on computing and logical elements, and on the 1103's programming and I/O facilities. It's pretty informative as an introduction to 1103 "technology". Other bitsavers 1103 documents from 1953 forward identify "ERA 1103" versus the "Univac Scientific Model 1103A". But - no schematics, no list of unit chassis numbers were immediately evident in my quick look. It may be difficult to find a manual for the specific module held by VCFed. The image in the PDF from Evan is blurry. A better image may show a "unit chassis" part number that can be Google searched to find a document with specific information. This is a hint. Why will a unit-chassis manual be difficult to find? I'm "guessing" that most of the Univac manuals were for use on-site to operate the Univac, or off-site to learn how to program it. The point of modular construction, was to allow on-site persons to run test operations on the computer, to identify down to the "unit chassis" any problems. Then the unit chassis could be pulled, repaired off-site, and/or replaced on site. Military procedures for system repairs may have been different. lose reading of the "sysMaint" manuals may reference that process and would be informative. Herb Johnson -- Herbert R. Johnson, New Jersey USA http://www.retrotechnology.com OR .net