There's a 1958 NEC 1103 Parametron computer brochure online at
http://archive.computerhistory.org/resources/text/NEC/NEC.1103.1958102
646285.pdf
I think it's interesting that the term "sexadecimal" is used.
Apparently, NEC had none of the puritanical qualms of IBM. The
numbering notation seems to be 0123456789DGHJKV.
Cheers,
Chuck