Subject: Re: Super Serial Card II, Modem/Term Block
Newsgroups: comp.sys.apple2
From: dempson@actrix.gen.nz (David Empson)
Date: Tue, 2 Feb 1999 02:52:50 +1300
Message-ID: <1dmku5t.1igfmwd1r98h9zN@dempson.actrix.gen.nz>
References: <78cvqu$31i6@ds2.acs.ucalgary.ca> <david.917155803@wraith>
Organization: Empsoft
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David Wilson <david@uow.edu.au> wrote:

> wbdesnoy@acs2.acs.ucalgary.ca (Byron Desnoyers Winmill) writes:
> >While playing with my serial card I managed to break pin 9 on the 
> >modem/terminal switch block.  Is this pin significant?  If so, how would
> >I wire-up a new connector or bypass this pin?
> 
> This is from memory (I can only lay my hands on the 2nd edition of the SSC
> manual - the dumbed down one with no circuit diagram)

Thank god I kept mine.  I don't know what Apple were smoking when they
produced all the newer manuals that have no useful information in them.

> but if you can get a male DIP header solder the following pins and you
> will have a replacement module.
> 
>       1-16
>       2-15
>       3-14
>       4-13
>       5-11
>       6-12
>       7-9
>       8-10

That doesn't look anything like the wiring diagram given in the original
SSC manual.  It is (roughly) how the logical diagram is drawn, but not
how it is actually wired.

The diagram in the manual shows it as follows:


          1 --    -- 16
              |  |
          2 --    -- 15

          3 --    -- 14
              |  |
          4 --    -- 13

          5 -------- 12

          6 -------- 11

          7 -------- 10

          8 -------- 9

> No idea what signal goes through pin 9 nor which orientation of the above
> results in terminal or modem mode.

Pin 9 on the socket is the DTR output of the 6551.  In the MODEM
orientation (as drawn above), this does to DTR (pin 20) on the
connector, hence you will not have a DTR output any more.

In the TERMINAL orientation (rotated), pin 9 goes to pin 10, which is
DSR (pin 6) on the connector.


(If you actually broke off pin 1, then you have lost the CTS input in
modem mode, which is unused in terminal mode.)

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand