It sounds like my house is similar to others on this list....
Anyway, while extracting an off-topic device, I came across a ring
binder that I had labelled 'HP9831 Manual' Inside were the 2 volumes of
user documentation for that machine -- the Operating/Programming Manual
and the I/O Manual.
[The HP9831 has similar hardware to the 9825, but has BASIC, not HPL, in ROM]
A couple of things struck me from reading said documentation
1) There were 2 ROM modules made for the 9831 -- a Matrix/Plotter ROM
(which came in 2 versions to support either the 9862 or 9872 plotters)
and a Flexible Disk ROM. I have neither, alas. Has anyone ever seen them?
2) The I/O manual describes all the peripherals available for the machine
_including the 9877 External Tape Memory_. It appears that the 9831
firmware supports this device for loading/saving BASIC programs and data
files (although not for doing bit-level copies of tapes, etc).
Unfortunately it says nothing about the actually interface for the 9877
-- for all other peripherals (printers, card reader, paper tape punch,
paper tape reader), it says that the interface is a 98032 16 bit parallel
module with the approriate 'option' (cable and link settings). Does
anyone know if the 9877 _definietly_ connected via a 98032 as well? Even
better, does anyone know the wiring?
-tony