> I've been laying awake at night wondering which serial ports

;-)

> on a TT are wired to which chip.  A quick trawl through the
> port-atari archive suggests the following...
> 
>   Labeled   Old device  New device  Chip     Notes
>   ~~~~~~~   ~~~~~~~~~~  ~~~~~~~~~~  ~~~~~~~  ~~~~~~~~~~~~~~~
>   Serial2   /dev/ser02  /dev/tty00  8530 A   Also LAN port?
>   Modem2    /dev/mdm02  /dev/tty01  8530 B
>   Modem1    /dev/mdm01  /dev/tty02  1st MFP
>   Serial1   /dev/ser01  /dev/tty03  2nd MFP  Missing lines?
> 
>             ...could someone confirm or correct this for me?
> I would also be interested in knowing what kind of through-
> put to expect from each port.

The table is correct - the mapping between "Labeled" and "New device" is
the one you want.

I used to have a 33.6K modem connectect to Modem2 and run the connection
between TT and modem at 38400.  I can't remember the interrupt rate when it
was receiving at full speed, but I seem to remember it using over 50% CPU.
The problem is getting incoming characters out of the 3-byte fifo on the
chip and into the software buffer.  I did save some stats for the same setup
on a Sun 4/330 (similar ZS8530 serial chip) which show it running at roughly
8000 interrupts/second (59% interrupts on a 25Mhz CPU).  If you run `sysstat
vmstat`, you can see the interrupt rate and CPU usage.

> Does anyone here happen to know which signals are missing
> from Serial1?  I was looking at a MegaSTE schematic last
> night, which seemed to have the DSR input (pin 6 on a DB9)
> not connected.  Perhaps the TT's Serial1 is more severely
> limited?

I hunted down my TT manual last night.  The missing lines are:

	Modem1		6 (Data Set Ready)

	Serial1		1 (Carrier Detect)
			6 (Data Set Ready)
			8 (Clear To Send)
			9 (Ring Indicator)

On Serial1, pin 4 (DTR) and pin 7 (RTS) are alwyas asserted when the TT is
powered on.  On Serial2, pin 9 is conencted to "Synchronous Clock"

J
 
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