An easy one (after that db9 debacle!) - test-drb@ccmp.vtda.org

15 Dec 1999

... and it was a DE9 debacle! . . .

Dick

-----Original Message-----
From: Tony Duell &lt;ard(a)p850ug1.demon.co.uk&gt;
To: Discussion re-collecting of classic computers
&lt;classiccmp(a)u.washington.edu&gt;
Date: Wednesday, December 15, 1999 7:14 PM
Subject: Re: An easy one (after that db9 debacle!)

...
 > This one should be easy. I've got an ESDI
drive, I know that at one time it
...
 > had termination resistors in it, I know that I
pulled them out, I put them
...
 > into my "drawer of misc resistor packs",
they are effectively invisible :-)
...

 What is the resistor values for the term pack? 220/330? 
Almost certainly. May be marked 221331 (==22*10^1, 33*10^1). I would
guess the pinout is one of the standard ones (SIL with the common pins at
the ends, DIL with the common pins at the top right and bottom left corners)
...

The latter assumption is not always valid. I once worked on a floppy
drive that was corrupting disks. The cause was the termination resistor
pack. It was a 9 pin SIL, but instead of having the common pin at one end
(marked by a dot), it had it in the middle. The correct resistor pack was
symmetrical, therefore. Somebody had put in a normal resistor pack, and
the result was that all sorts of signals got coupled together. Finding
that fault was entertaining to say the least.

-tony