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tlug: Re: SLC Serial Port Question

tlug note from (John Little)
% I was wondering if you could help me wrt the serial connector on the
% back of the SLC.    It has  a single DB-25 connector which seems to be
% labeled as a A/B (or is it 1/2) serial port.   Hence I assume that the
% single connector actually contains two serial ports.
% I want to hook up a modem to my SLC so am wondering if I need a
% special cable, or whether  I can just use a std (straight??) 25pin
% cable?

   Okay, here's the scoop on the SLC serial. 

	   Pin		Port		Function
	   ====		====		========
	   2		A		Transmit Data
	   3		A		Receive Data
	   4		A		RTS
	   5		A		CTS
	   6		A		DSR
	   7		COMMON		Signal Ground
	   8		A		DCD
	   15		A		TC
	   17		A		RC
	   20		A		DTR
	   24		A		TCO

	   14		B		Transmit Data
	   16		B		Receive Data
	   19		B		RTS
	   13		B		CTS
	   12		B		DCD

   As you can see, the "B" port doesn't have any of the clock signals 
   needed for synchronous modems, so if you're planning to use a 64K
   leased line you'll have to stick to the "A" port. :-)

   Other than that, you probably *don't* want to use a cable with all
   25 pins connected (flat ribbon-type cables are *not* good candidates
   for SLC to modem connectors). Stick with the pins tagged as "A" and
   you should be okay (you can forget the transmit-clock, receive-clock
   and transmit-clock-out lines when you're using a normal, async

   Now the gotcha... Various people on the SPARC-Linux list have
   reported very poor throughput characteristics when using the serial
   ports on the older SPARCstations. :-(  For some reason, this seems
   to be one of the areas where SunOS actually outperforms Linux. Linux
   will work, but you'd probably be better advised at this stage to use
   a PC or Mac as your main dial-up interface machine.


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