The S/360 Model 50 used CCROS and, yes, the "cards" could be punched in a 029 keypunch (I saw my IBM CE do this several times to apply microcode patches).
CCROS seemed to be rather error prone and the Model 50 was not known for its overall reliability. My IBM CE used to be fond of saying things like "if you dropped a Mod 50 in the middle of the ocean it would sink -- intermittently". Bob On Sep 6, 2011, at 09:04, Paul Gilmartin wrote: > I find: > > http://www.cs.clemson.edu/~mark/uprog.html > > there were various technologies: TROS (Transformer Read Only > Storage), BCROS (Balanced Capacitor Read Only Storage), CCROS > (Card Capacitor Read Only Storage). Perhaps others? It says > that the mylar dielectric of CCROS could be punched using a > standard (029?) card punch. > > -- gil
