Does anyone know if the spiral bound HP-12C manuals are authentic? I have a glue binding manual and a spiral bound manual. There are slight differences as follows which makes me believe they are both authentic:

Glue bound
- p/n 00012-90001 edition 1
- printed in the USA, July 1987
- back cover says Corvallis Division
- no manufacturing number on back cover

Spiral binding
- p/n 00012-90001 edition 1
- printed in the Canada, July 1987
- back cover says Portable Computer Division
- manufacturing number 00012-90023

Looking thru both books I see some font differences here and there. To me the spiral bound manual does not look like a repro of the glue bound book. The pages in my spiral binding manual also have a very slight yellowing. Looks like the real thing to me.

Anyone else come across this before?

Thanks

HP issued both spiral bound and glue bound manuals at different times. Generally the spiral bound were earlier, and the glue bound later. Presumably the glue bound were less expensive to produce.

The edition date is the date of the contents, and doesn't provide much insight into when the particular manual was printed.

Edited: 28 Feb 2012, 4:06 a.m.

A lot of fun - and confusion - can be had with dates of editions and of printing. Information on when the manual was printed is often available in small print (obviously!) on its back cover. Even this does not necessarily tell you if a manual is earlier or later than others for the same calculator, as an earlier version of the text might have been reprinted later in a different country.

An illustration: