Problems with Specific ttym Ports

[Wayne Podaima]

We have a 4D/240S, 260S, and 280S.  On all 3 machines the same 4 RS-232 ports
(2 on 240) fail to respond when configured as ttym; they do work as ttyd.
The other 5, 7, or 11 ports on the various machines work fine as ttym.  All
ports are configured identically in /etc/inittab.
The 4 ports which do NOT work are: 47, 48, 51, & 52.

Any suggestions, or comments of similar experiences are appreciated -
especially before the SGI tech. starts replacing cpu, IO2, & IP7 boards,
backplanes, ...

Thanks,
  Wayne Podaima   wjp at vm.nrc.ca