V.C.F. wrote...
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I'm trying to interface a DEC CR11 (a.k.a. Documation M200) card reader to
an Apple ][.
I need the pinouts of the card reader interface. Does anyone have this
information? Is the service manual available online (in some nook I
haven't looked into yet)?
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Dang! Where was that link (from a following message) a couple of years
ago when I was trying to do something similar??? <G> Using an Altair
for a card reader controller to connect to a PC... <snicker>
One thing to watch out for that bit me REAL hard when doing this, is that
the data lines on the connector are the raw, unlatched outputs from the
phototransistors, and the mechanically generated 'column strobe' signal
has a significant amount of slop/jiggle/window (pick your favourite) in it
and needs some 'processing' in order to insure valid data.
I ended up recreating a circuit that I found detailed in the DEC CR11
Interface Board docs. It used a couple of monostables to delay the
'column strobe' signal by an amount, and then stretch the signal for
reliable triggering. (or was it the other way 'round? - stretch then
delay?)
Anyway... without the 'processing' of the strobe signal the data was
completely unreliable. To the point of appearing totally random!
Hopefully someone has this doc at hand (or it is covered in the
reader hardware manual) for reference. Mine is still buried somewhere in
the chaos!
Good luck!
-jim
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jimw_at_agora.rdrop.com
The Computer Garage - http://www.rdrop.com/~jimw
Received on Sun May 05 2002 - 11:22:11 BST