It's not either! First, I looked at the MM11-L TM, and it talks about how the H214 has "mats" (2D arrays of cores), 1 mat per bit; the H214 has 16 mats. So definitely no effectively 36+ bit wide variant. So, pairs? Well, I looked to see what PDP-10 memory TM's were extant, and there's one for the MF10 (A-MN-MF10-0-MAN-1); and glancing in it, it _does_ use the H216 - with "19 mats" to produce "19-bit word memory banks"! (Exactly how, I didn't have time to stop and read. It's got to be pairs, but at the bank level, not board.) So our guess as to which generation of PDP-10 memories it was used in might have been wrong... Noel