[Ham-Mac] Re: DarwinPSK question

[Steve Hellyer]

Hi all:

The default Mac serial ports are RS-422 (using mini-Din 8 connectors in 
this case). This RS-422 signalling applies similar voltage levels as 
RS-232 but uses a differential means to determine if voltage was high 
or low on a pin vs absolute voltage levels as used in RS-232 . The 
result is ability to use longer cable and/or higher speeds than RS-232.

Pin outs look like this:

	• 	1 - HSKi Handshake or Clock input
	• 	2 - HSKo Hanshake output
	• 	3 - TXD- Transmit Data inverted
	• 	4 - Signal Common
	• 	5 - RXD- Receive Data inverted
	• 	6 - TXD+ Transmit Data non-inverted
	• 	7 - GPi General Purpose in
	• 	8 - RXD+ Receive Data non-inverted

What appears to be a strange set of pins was very handy to Apple as it 
provided for LocalTalk or PhoneNet networking at 230Kbps.  Anyone 
remember that? :-)  Hence as you can see these serial ports can go very 
fast.
It also eliminated the need for modem and null-modem type cabling 
between RS-422 devices. 8 pin to 8pin the same cable could be used for 
a printer (DTE) or modem (DCE).

But there is another bonus for choosing RS-422. It can also perform 
RS-232 signalling.  Buy connecting Pin 8 to pin 4 to ground it signals 
to the chipset on the Mac to use RS-232 absolute signalling at 5v.

Here is a great link which provide pinout, cable diagrams as well as 
much more detail that I have provided here.

http://www.hinton.demon.co.uk/mac/mac_if.html#modem

Hope this helps some!

73
Steve
VA3SPH

On 2-Oct-04, at 4:58 PM, G7BSK wrote:

>>>
>
> Thanks Volker, the socket on the keyspan adaptor is 8 pin miniture DIN 
> type and I am sure that pin 8 is the frame, but thanks for the advice 
> anyway.
>
> BTW is Ver 0.8.4 the latest or has a new version come out.
>
> 73's
> Jason, G7BSK
>>>
>> Well, DarwinPSK drives RTS and DTR. These are Pin 4 and 20 with an 24
>> Pin connector. With an 9 Pin connector I think you can use Pin 8. I
>> don't know if it's DTR or RTS .
>>
>> 73, Volker, DL1KSV
>>
>>> Also does anyone know if Ver 0.8.4 is the latest?
>>> 73's
>>> Jason
>>> G7BSK
>>> ------------------------------
>>> _______________________________________________
>>> Ham-Mac mailing list
>>> Ham-Mac at mailman.qth.net
>>> http://mailman.qth.net/mailman/listinfo/ham-mac
>>> End of Ham-Mac Digest, Vol 9, Issue 1
>>> *************************************
>>
>>
>>
>> _______________________________________________
>> Ham-Mac mailing list
>> Ham-Mac at mailman.qth.net
>> http://mailman.qth.net/mailman/listinfo/ham-mac
>>
>
> _______________________________________________
> Ham-Mac mailing list
> Ham-Mac at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/ham-mac
>