[comp.sys.ncr] Telebit modem on ttya or ttyXX ???

merv@gpstwr.UUCP (Merv Graham) (03/01/90)

We are now installing a Telebit T2500 modem on our tower (400).
It is now running just fine at 9600 baud on ttya.

Question:
	If I try to run it at 19.2kb on ttya will it put more of a load on
the main CPU (68020) slowing the system down more than if I put it on
another port (HPSIO) which has a 6809 to handle some of the I/O
interface?

Any comments, experiences, etc. would be appreciated.  E-mail if you
don't think they would be of general interest.

Thanks, Merv 
-- 
Merv Graham                 |     merv@gpstwr.UUCP
Graham-Patten Systems, Inc. | or: tektronix!gvgpsa!gpstwr!merv
P.O. Box 1960               | 
Grass Valley, CA 95945      | Ph: 916-273-8412   FAX: 916-273-7458

wescott@Columbia.NCR.COM (Mike Wescott) (03/05/90)

In article <500@gpstwr.UUCP> merv@gpstwr.UUCP (Merv Graham) writes:
> We are now installing a Telebit T2500 modem on our tower (400).
> It is now running just fine at 9600 baud on ttya.

> 	If I try to run it at 19.2kb on ttya will it put more of a load on
> the main CPU (68020) slowing the system down more than if I put it on
> another port (HPSIO) which has a 6809 to handle some of the I/O
> interface?

Yes, it will slow the cpu down significantly.  That's why the hpsio's
were developed (they have a 68010, not the 6809).

Moreover an ordinary 400 probably can't drive a telebit at 19.2kbps on
ttya or ttyb.

--
	-Mike Wescott
	 mike.wescott@ncrcae.Columbia.NCR.COM