[comp.sys.dec] Can Ultrix 3.1 getty autobaud to 19200?

obg@vale.is-jfa.kth.se (Olof Backing) (02/10/91)

From what I've heard, the DEC2100/DEC3100 is not able to use higher
speeds that 9600 due to the fact that these machine have "borrowed"
some parts of the hardware directly from VAX's. The VAX's had the
same problem that they couldn't use higher speeds than 9600.
If you have newer models than 2100/3100, you'll be able to use 19200.
That's what I've been told about the RISC-side with Ultrix. How this
applies on the VAX's, I don't know.

-- 
Olof Backing                              Royal Inst. of Techn., Sweden
Professorsslingan 25/102                  Internet: obg@is-jfa.kth.se
S-104 05 Stockholm, Sweden                Voice: + 046 8 166318

grr@cbmvax.commodore.com (George Robbins) (02/11/91)

In article <303@asihub.autosys.com> dano@asihub.autosys.com (Dan O'Neill) writes:
> 
> Problem:    I would like to have getty autobaud to 19200, the getty
> 	    in ULTRIX 3.0 (VAX) doesn't seem to support this speed.
> 	    Am I correct, and if so, is there a way to patch getty
> 	    to support a speed of 19200?

I played with it a long time ago, and concluded that it didn't
want to work.  The general technique is to set the speed to some
value and see what kind of garbage is detected when a return is
received.  I think the way it's set up, anything 9600 or above
yields the same result.  You'd have to change the initial trial
speed or do a second pass to distinguish faster rates from the
olde 300/1200/2400 junk.

Sequencing via breaks seems to work just fine though, although
there's no guarantee that all DEC interefaces suppport 19200,
although most do, unofficially.

Note that if you were getting autobaud action by the fact that
sending random characters at the wrong speed causing framing errors
which unix seems to treat pretty much like breaks, I guess the
stuff at 19200 just doesn't seem like breaks.

-- 
George Robbins - now working for,     uucp:   {uunet|pyramid|rutgers}!cbmvax!grr
but no way officially representing:   domain: grr@cbmvax.commodore.com
Commodore, Engineering Department     phone:  215-431-9349 (only by moonlite)