[rescue] Trying to get Cadmus 9200 running (serial console trouble)

Meelis Roos mroos at linux.ee
Wed Feb 6 01:31:53 CST 2019

> Is the garbage consistent?  That is, if you type (say) x, do you always
> get the same garbage back?  (It's not clear whether your "different for
> each character" means "differs from one typed character code to a
> different code" or "differs from one instance of a given character to
> another instance of the same character".)

I retried it. it's less consistent than I remembered.

Aaa at a@aa at aa@aaaaaaAaA at AAaAa@aAcssssbscsbbsbbsbssbd``DD at d@`@d`d at d@ddD at D@`@`dDDDddfDfDDfDdDfffDf
``qqqqqqqqqaaq`qqqqa`a`aqqqqq`qaq`qvwwwwwvwwwwwgwvwwwvwwwwwADeDe at eAe@eDDaDdaeEeaeaDae`eDED


> If so, or even if just _usually_ so, this sounds a lot like a parity
> mismatch to me (eg, the terminal using 8N and the machine using 7E).

As a surprise, 7E did not change the above in any noticable way.
It just reads its own output back, somewhat garbled but with the same parity?

About the black cable:

> I'd actually be tempted to buzz out all 25 pins, since it's only an
> assumption that it's standard serial port pinout.  Unless someone knows
> Cadmus used standard pinout...?

I opened the connector casings and looked the the colors of the wires.
There is DB25M on one end and DB9F on the other so I actually used multiple
adapters to get from PC to Cadmus (so I have not yet mapped the whole chain).

All the lines in the black cable were direct 1-1, no bridges.

DB25  DB9
2      3
3      2
4      7
5      8
6      6
7      5
8      1
20     4
22     9

That appears to be a standard DB9-DB29 adapter as per https://www.lammertbies.nl/comm/cable/RS-232.html page.

Cadmus docs about RS232 cables denote DB9 pins as

1 shield
2 data out
4 bridged to 5 in some cables
5 bridged to 4 in some cables
9 data in

Their drawing about pin locations is the following:
1 to 5 are the long upper row from left to right
6 to 9 are the short lower row low from left to right
when viewed from cable side.

That really seems different from what the above descriptions used.
Which means I probably have to solder a custom cable when I figure out what I need.

Meelis Roos <mroos at linux.ee>

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