Help needed reading Ford EEC-IV data stream

[m_mcdonald at marx.ENET.dec.com]

I'd like to write a program to tap into the data stream, via the
diagnostic connector, on my 1993 Ford Escort with its 1.9 liter
engine.  If the data stream consists of standard RS232 signals,
I might be able to use a datascope as the first step in writing
a BASIC program.  This program would read (not write) the data
stream via a laptop's standard serial port.

Diacom is a product of Rinda Technologies in Chicago that uses the
parallel port of a PC to extract much information from the ALDL
connector of GM cars and from the corresponding connector (don't
know its name) of Chrysler cars.  They told me that pre-OBD-II
Fords, such as my EEC-IV Escort, don't have much information beyond
stored error codes available at the diagnostic connector. 

I know that a Snap-on Model MT2500 scanner hooks into the Escort's
diagnostic connector and displays data -- definitely beyond stored
error codes -- on its 4-line screen.  I'd like to write BASIC
programs for a PC that read the signals coming from the connector,
save them, and reformat them for display.

Any suggestions about how to get started?  For example, if I knew
the structure of the signals (1200 baud, odd parity, etc.), then
constructing BASIC statements to read this data stream through a
standard PC serial port should be straightforward.  There are
six pins in the Escort's connector plus a seventh wire.  How would
I connect a cable from what pins of a DB-9 serial port connector
to what seven wires at the Escort's connector?

BTW modern cars come and go, but a 1940 Ford coupe with a flathead
V-8 engine has been the real car in my life for the past 19 years
and in the future.  It was a a genuine learning experience to convert
the distributor from breaker points/condenser to optical pickup/
electronic coil control while keeping the 6-volt positive-ground
electrical system intact.

Many thanks for your help.

Marll McDonald   KB1AGM
m_mcdonald at marx.enet.dec.com