Re: SparcStation 4 serial console

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

> 3.  If memory serves, the ss4 has a port that combines ttya and ttyb
> into one DB-25 connector.

Most pizza-box Suns do, yes.  I too think the 4 is one of them, but
it's been too long since I used one for me to be sure.

> If you're using a 3-wire serial connector on the port, wired only for
> one serial port, then you should have no trouble.  If, however,
> you're adding extra pins, be careful you're not hitting lines that
> are used by ttyb instead of ttya from the ss4's perspective.

You aren't likely to.  Sun was smart; they used the RS-232 standard's
"secondary" lines, so they won't collide with any of the main port's
lines.  (For example, pin 16 is "Secondary Received Data"; it is the
ttyb version of what ttya puts on pin 3, "Received Data".)  See also
below.

> I don't remember the pin-outs, but I'm sure there's a document
> running around on the Internet that tells those details.

Probably.  Here's what my notes say (I think this came from RS-232C):

Pin	Source	Type	What
 1		Ground	Shield, protective ground
 2	DTE	Data	Transmitted Data
 3	DCE	Data	Received Data
 4	DTE	Ctl	Request To Send
 5	DCE	Ctl	Clear To Send
 6	DCE	Ctl	DCE Ready
 7		Ground	Signal ground
 8	DCE	Ctl	Received Line Signal Detector
 9			(Reserved for testing)
10			(Reserved for testing)
11			(Unassigned)
12	DCE	Ctl	Secondary Received Line Signal Detector
	DCE	Ctl	Data Signal Rate Selector (DCE)
13	DCE	Ctl	Secondary Clear To Send
14	DTE	Data	Secondary Transmitted Data
15	DCE	Timing	Transmitter Signal Element Timing (DCE)
16	DCE	Data	Secondary Received Data
17	DCE	Timing	Receiver Signal Element Timing (DCE)
18	DTE	Ctl	Local Loopback
19	DTE	Ctl	Secondary Request To Send
20	DTE	Ctl	DTE Ready
21	DTE	Ctl	Remote Loopback
	DCE	Ctl	Signal Quality Detector
22	DCE	Ctl	Ring Indicator
23	DTE	Ctl	Data Signal Rate Selector (DTE)
	DCE	Ctl	Data Signal Rate Selector (DCE)
24	DTE	Timing	Transmitter Signal Element Timing (DTE)
25	DCE	Ctl	Test Mode

As I say, the ttyb lines are the "Secondary" ones:

12	DCE	Ctl	Secondary Received Line Signal Detector
13	DCE	Ctl	Secondary Clear To Send
14	DTE	Data	Secondary Transmitted Data
16	DCE	Data	Secondary Received Data
19	DTE	Ctl	Secondary Request To Send

("Received Line Signal Detector" is, IIRC, what commonly gets called
CD, for Carrier Detect.)

I have another set of notes which says that ttya's pins are

2	txd_a	o	transmit data
3	rxd_a	i	receive data
4	rts_a	o	ready to send
5	cts_a	i	clear to send
6	dsr_a	i	data set ready
8	dcd_a	i	data carrier detect
15	trxc_a	i	transmit clock
17	rxc_a	i	receive clock
20	dtr_a	o	data terminal ready
24	txc_a	o	transmit clock

and ttyb's are

11	dtr_b	o	data terminal ready
12	dcd_b	i	data carrier detect
13	cts_b	i	clear to send
14	txd_b	o	transmit data
16	rxd_b	i	receive data
18	rxc_b	i	receive clock
19	rts_b	o	ready to send
25	txc_b	o	transmit clock

(I don't know why there is a transmit clock sourced by each side in the
standard - see pins 15 and 24.)

To the extent that this second set is accurate, it indicates they
reused three little-used pins (11, 18, and 25) to carry signals the
standard doesn't have a "secondary" version of.  You _still_ aren't
likely to collide with ttyb accidentally when wiring up a ttya
connector.

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