Serial port diffs 3/60 - 4/60

[klaus u schallhorn]

Does somebody know if there are known problems with the serial drivers on
a 3/60?

Background: In cleaning up and final testing of my faxpak [to be posted in
a week or two] I came across some fax files that would not go through the
serial port on a 3/60, no matter how hard I pushed. The same files can be
sent:

	on a 3/60 if under the control of trace(1) and/or script(1)
	on a 4/60
	on a msdos box

No, I do not overrun any buffers, the kernels are [except for machine
specifics] based on the same configs and the problem can be reproduced
wiht a 100% "success rate".

Any ideas, hints?