Internal HP docs on 9845 sys?

Hi everyone, I've been working for the last few months on implementing the MAME emulator of HP 9845B system. In case you're interested, have a look at MAME development page at https://github.com/mamedev/mame. My emulator mostly works, the main missing thing now is the graphic mode and the ability to load optional ROMs. Anyway, I'm posting here because I'd like to ask you a few questions on HP docs. The last thing I worked on for this emulator is the "TACO" tape driver. I reverse engineered it entirely from sw & the (scarce) docs available enough that it works. So here a few questions for you: * Back in the days, what was the HP approach to document internally-developped chips for its own sw developers? I mean, was there a kind of programmers' guide for TACO chip? Is there any hope someone scanned it and made it available somewhere? I know that for hybrid processors HP made an internal manual titled something like "how they do dat" manual... * Just out of curiosity, what a big company like HP does with its "historical" documents? Do they have an archive where they keep documents & sw from, say, the 70s? Or do they throw everything away when there is some kind of company "shake-up" such as big layoff phases, closing of a site, merging and splitting of divisions? Thank you. -- F.Ulivi