OK, so the fix turned out to be as simple as deselecting the "Use 
hardware handshaking" option for the Mac's terminal emulator program. 
I must have turned that on since the last time I booted into NetBSD 
on that machine.  :(  Obviously SRM isn't as fussy about the state of 
the handshaking lines as getty.

Thanks for your patience, and to whoever recoded the kernel so it can 
detect which console to use automatically; that's very convenient.

>Could you post your /etc/ttys file?

/etc/ttys hadn't been changed since the initial installation, but 
when I read it I was surprised to see it contains these lines:

# DEC 3000 Z8530 ("scc") serial ports
ttyB0   "/usr/libexec/getty std.9600"   unknown off secure
ttyB1   "/usr/libexec/getty std.9600"   unknown off secure

It seems, since these are both turned off, I was wrong in my 
assumption that the alternate console port on the 3000/400 is driven 
by a Z8530?


Ray