UrQ computer

[R1chT@aol.com]

I found out about this list only recently. I bought a modem partly so I could
tap into this collective audi knowledge base. I bought my '83 UrQ (#335)
about 2 years ago, knowing nothing about these cars. Since then I have
generated a few questions, and may perhaps, have some info to share as well.
I have several issues which may find their way to the list.  I am looking
over the archives, and have already gleaned some useful insights, but I don't
yet see anything about the following:

One of my first problems was an intermittant no start, or sudden engine cut
out situation, which I finally traced to a semi-corroded foil underneath one
of the IC's in the fuel timing computer. 

While trouble shooting this problem, I generated a nearly  complete schematic
of the circuit, as an ORCAD file, which I will share if anyone is interested.
Although I was able to fix the problem I would like to increase my
understanding  of the circuit.

Questions:

1) Does anyone have specs on the Hitachi HD46506? This is an IC, which
Hitachi USA claims never existed.
2) How about a source code listing?
3) Are there more than one version of this computer?
4) I'm sure there has already been some discussion of ROM upgrades, I'd like
to hear of others' opinions on the available ROMS.
5) I've been thinking of making a breakout box to show the status of what the
computer sees. Has anyone already done this? Is the connector available
commercially?

TIA

Rich Thomas
Concord NH