Dear All,

This may have been previously communicated as a tip, but some of
the exchanges on this subject indicate that the information may not
be easily locatable.
My thanks to Tony Anderson, Paul Globman, and others
who offered suggestions and to Phil Wheeler for FLTIBM.DOC which contained
useful information. The problem was a NULL modem hookup between
a Model 200 and an AT Clone (Epson Equity III+). According to
notes from Phil and my own poke at the internals of a Radio Shack
Null modem connector, this comes wired as follows.

 1 to 1, 2 to 3, 3 to 2, 4 to 5, 5 to 4, 7 to 7, 6 and 20 to 8.
		 ______  ______  ________________________
		|      ||      ||         \              |
	    1	2    3 |4    5 |6	7  \	8	20
	    | 	    /  |    /  |        |   \    \           
	    |	   /   |   /   |	|    \    \
	    |	  /    |  /    |        |     \    \
	    |	 /     | /     |	|      \    \
	    1	2    3 |4    5 |6	7	8    \ 	20
		     |_|     |_||_____________________\__|
		     
I have used the Radio Shack Null modem as described above to connect
a large variety of devices. Model 100 to AT, PC, Prime, DEC PDP-11,
Wang VS, MicroVAX. PC to DEC, Other PCs, ATs, Wang VS, Prime and so on.
I carry about five of them and use them all the time. It is an excellent
general purpose hook up.

I was very surprised then that I could not get it to work on a Model 200 to AT
hook up. Based on suggestions from Tony and others, I modified one of
these Radio Shack connectors to the following.

 1 to 1, 2 to 3, 3 to 2, 4 and 5 together, 7 to 7, 6 and 20 to 8.
		 ______  ____    ________________________
		|      ||    |  |         \              |
	    1	2    3 |4    5  6	7  \	8	20
	    | 	    /  |                |   \    \           
	    |	   /   |        	|    \    \
	    |	  /    |                |     \    \
	    |	 /     |        	|      \    \
	    1	2    3 |4    5  6	7	8    \ 	20
		     |_||____|  |_____________________\__|
		     
The modification is easy as the 4 and 5 wires can be clipped and twisted
together and all other connections are left the same way.

This works for the 200 and still works for the 100 to AT hook up, so
I don't have to swap connectors when I swap portables.

You can of course make either of these on your on with the connectors and a
soldering iron.

Best,
Mo Budlong 76167,3310.


Sysop Note: 6/9/89

The above modifications to a Radio Shack Null Modem may have been possible with
early models of the device, but the current model, Catalog # 26-1496A, cannot
be modified in this manner.  It is housed in a gray plastic covering, and the
entire interior is encapsulated in a white rubber compound, preventing access
to the wires connecting the plug and the socket at each end.  This model sells
for $7.95 at the present time, and the earlier model sold for $16.95.  This
should be a good indication of the ones that can be modified, and the ones that
can't.  But it's just about the same cost to make one from scratch, using the
appropriate parts, also available from Radio Shack.