[rescue] automatically booting a sun 3/50

[schaecsn]

Hi folks,

I do have a sun 3/50. I would like to boot automatically sd(,,4). but
after I turn on the computer I need to enter manually "b sd(,,4)"
because I get the following "error" message:

Diagonstic autoboot in progress...
invalid Device=''
>

how can I convince my sun to boot directly sd(,,4)?

if it should matter, my rom revision is 2.7 and the precise model is
3/50M.

thanks, Stefan