Question on '71B Hardware Interfaces

[mcquiggi]

Hi All:

I'm a newbie. I acquired a '71B a couple of weeks ago, as I liked the look of the machine. Really cool! My background is in "Jurassic" computing science so I liked the idea of the '71B as a BASIC device.

I've been reading the forums and corresponding with some members - what a great resource and a knowledgeable group of people here!

I have historical experience with HP calculators, from my school days and a through my work, but most of my HP experience has been with their test equipment - signal generators, spectrum analyzers, and the like.

My post here concerns the hardware interfaces on the '71B - the ports that accept RAM, ROM, etc. Are there specifications available for these? I am interested in (potentially) building my own device that can add functionality/memory/? to the '71B through connection to these ports.

In the least, I see 4K RAM modules on eBay for $32: while I value "stock" parts, I am sure that it must be possible to build one's own RAM module for far less than $32, if the specs/schematics are available.

I've seen the Pil-Box, that is neat, but it is more of a network-side interface.

Perhaps these port-side devices exist already and I haven't found them yet. I've seen the FRAM device but my own '71B has a card reader so that port is taken! I'd like to leave the card reader in place.

Anyway, my apologies if this an RTFM question, but on a bit of a search I couldn't find anything quite relevant.

Kevin