Subject: Re: Serial port names
To: NetBSD port-atari mailing list <port-atari@netbsd.org>
From: Julian Coleman <jdc@coris.org.uk>
List: port-atari
Date: 07/11/2003 12:57:36
> Thanks, that's good to know.  I still haven't found my TT
> schematics, but I did unearth MegaSTE drawings, which may be
> similar where the serial ports are concerned.

I think so - they both have the MFP- and SCC-driven ports.  Although, I think
the Mega-STE has one MFP like the STE and the TT has an additional one (which
drives Serial 1.

> The processor overhead might not be a problem with a simple
> terminal emulator program, but it sounds as though anything
> as hefty as a graphical Web browser is likely to suffer.

I don't know of a decent lightweight graphical web browser.  I tend to use
lynx for most of my browsing.  Things like galleon or mozilla will want
large amounts of memory and faster processors to run at a reasonable speed.
Also, bear in mind that the processor utilisation is while you're receiving
- as soon as you stop receiving and start rendering the page, you don't use
the CPU cycles for the serial interrupts.

> Hmm... will my 4/65 suffer the same problem?

Yep, almost all the sparc's (along with the early sparc64's) have the
ZS8530 chip.

> If I were connecting a serial terminal to a NetBSD TT, would
> it (getty?) use DCD to detect the presence of a terminal?

Depends ;-)  If you look at the manual page for /etc/ttys (`man ttys`), you
can set the "softcar" flags to ignore it.  You can also use the "local",
"rtscts" and "mdmbuf" to alter getty's behaviour.

(Serial 1)
> That seems an odd combination of signals to omit, but I'm
> sure it made sense to someone at Atari.

Presumably something to do with the lines they could get out of the second
MFP in the TT.

> Does the LAN port lack hardware flow control signals
> (HSKo/HSKi or RTS/CTS) too then?

The LAN port is shared with Serial 2, if I remember correctly.  Anyway, its
pinout is:

		  _________
		 /    @    \
		| 8   7   6 |
		| 5   4   3 |
		|   2   1   |
		 \_________/

	1	Handshakre Output
	2	Handshake Input or Internal Clock
	3	Transmit Data
	4	Ground
	5	Received Data
	6	Transmitted Data
	7	General Purpose Input
	8	Receive Data

I don't know the difference between "Transmit", "Transmitted" and "Receive",
"Received".  I guess a hunt through Apple Localtalk documentation might help.
As Localtalk is a bus, you can't have the same type of flow control.  All
systems use the same clock/line speed for synchronisation but I don't know
how contention is handled.

>   JC> On Serial2, pin 9 is conencted to "Synchronous Clock"
> 
> Is that an output from the TT?  RI may not be a big loss, I
> think most Hayes-style modems can indicate reception of a
> ringing signal with a string.

It's marked as both input and output.  I'm not sure how it's used.  Unless
you are using the modem on Serial 2 to answer incoming calls, you don't
need it anyway.

J

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                    My other computer also runs NetBSD
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