questions about using minicom with linux serial & grub menu

[PGNet]

hi,

i've minicom installed on osx.  i use a Keyspan USB-to-Serial
connector.  couple of questions ...

(1)

i can connect to a linux box's serial port @ 38400 bps, and see output
as expected.  slower speeds works as well.

if however, i switch to 115200, i get nothing-but-garbage in my minicom window.

the linux box, the keyspan adapter, the mac all support operation @ 115200.

what minicom magic have i missed?

(2)

i've set up linux boot so that the grub menu is presented to me over
the serial port in minicom.

as expected, i see the grub menu in the minicom window, but, so far
I've been un-able to grab control.

how do I interact with that menu?  i suppose a keystroke .... but which?

thanks.